Classic Winnebagos & Vintage RVs

Anyone know where to go about finding the fuel pump relay on an 89 P30 chassis with a 454?

We are vapor locking like crazy again, and I just put in ANOTHER electric fuel pump.  I'm going to pull the fuel line off and have Patti start the rig to see if fuel flows out, but if it does or doesn't, I'm starting to suspect either a bad fuel pump relay, loose wiring, or even a bad oil pressure safety switch going to the fuel pump.

We are out in the middle of nowhere, although I have a couple of generic relays that might work if I can find the suspect one.  And I'm not above rewiring the pump to bypass the OP safety switch if necessary, or rewiring the pump altogether temporarily to a toggle on the dash if necessary...lol!

Thanks!

Kev

Arent they down on the left side of the engine...almost under the drivers feat? I thought I read that somewhere?

Hey Kev You will have to get the specific wireing diagram for that veh. Looking thru my stuff nothing seems the same ! Usually fuel pump relays are easily accessable & have an open female connector close by to hot wire pump . One thing if you rewire the pump be carefull there are two wires at the sending unit one power for pump the other fuel gauge rheostate Do not supply 12 V to fuel gauge it will be destroyed or cause explosion !  If your veh uses a relay  The common Chevrolet relay wires are Tan & White , Orange 1, Orange 2 , Black & White , Green & White . The oil press switch supplys the ground for the relay when there is oil pressure . Frank

Thanks Frank!  First I'll pull the fuel line and have Patti start the engine to see if we have fuel flow.  Once that is confirmed...or not...I'll start checking the engine block for the oil pressure switches and make sure the wires going to them are connected.  Then trace that wiring hopefully back to the relay.

Thanks again!

Kev

Kev, my fuel pump relay is under the hood almost center and attached to the bulkhead. On mine there are 3 relays mounted together, fuel pump, ac compressor, and heater motor. These are Bosch  cube type relays, mine are black, but I've seen some gray ones on other GM vehicles. The relay will have four wires in it I believe. I'll look in my book  to see the color code in a bit, and post


Well the book shows 3 places it could be. 1 where I already said, 2 under the doghouse on drivers side, 3 inside of the frame rail in the rear.


The relay should have 4 but could have 5 or 6 wires in it.  The orange wire is 12v power, black= ground, dk/grn/wht is switched power, gray goes to the pump. It may also have a prime relay connected to it with red wires.

Kevin, I am in the same boat but it has been below zero here so I have not done any searching. What you need to do is follow the wire from the oil pressure switch, left side of engine behind the steering pump, and one of those wires will lead to the relay. The other will lead to a ground on the block or body. The safety switch is on a tee with the engine oil pressure sender. the pressure sender will only have one wire.
This is assuming what Frank said is true about the switch supplying the ground. You should be able to unplug that switch and with a paper clip or jumper wire bypass the the switch and then when you turn on the ignition you will have the pump running. If you do not then shut off the ignition and take your jumper off and turn the ignition back on and check the two wires in that plug for power with a meter or a test light. One should have power, ground that wire to a good ground and the pump should run. If it now runs then the other wire is not grounded good. When you ground the wire that has power at first just brust it against the ground. If you get a LOT of sparks then you might want to recheck the circuit and make sure this is not a feed circuit TO the pump. It SHOULD NOT be but I have seen things like this happen before.
Any questions be sure to ask. My e-mail is rickf1985@comcast.net (rickf1985@cmcast.net). You will probably get a quicker response.

If you touch that power wire to ground, you WILL blow the fuse, for sure.
That relay should have power on one leg all the time, then another should   have power with it running.

The wire we are talking about is the wire going through the oil pressure safety switch which is what closes the the relay. That should be the ground wire. The wire at the safety switch will NOT be the wire that powers the fuel pump. I will try to find a diagram to verify but that is standard procedure.

Thanks guys!  I'll be sorting this all out in a few days, and then let you all know my findings.

Anything else you guys find out, please let me know!

Kev

Hey kev have wire diagram too big to post on site send me your email address and ill send it to you   send it to gjtimney AT aol. DOT .com   good luck Gary

Thanks Gary!  I shot you an email.

Kev

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Source: Page 7-102 (H5D Emissions section) of the Chevy Motorhome Service Guide

Oil pressure switch is in this circuit.  This is a dual function switch (oil pressure and fuel safety cutout)

Refer to pdf page 139 (7-44) for mechanical layout

Refer to pdf page 141 (7-46) for electrical layout

Happy Trails to you,
Dave

Thanks Dave!  I saw a relay that looks like that in the front compartment screwed to the firewall when I did my headlight project.  It looked pretty crispy as I recall.

I'll take a closer look today.

Kev

BINGO!!!  Once again, Dave has come through with flying colors!

The relay was even approximately where the diagram Dave listed says it is...although I didn't see it at first, expecting it to be nearer to the back of the engine.

To find it, I first had to find the oil pressure sender, which is at the FRONT of the engine...the front lower driver's side corner of the engine block, directly under the power steering pump and AC pulleys if you dropped a plumb straight down.

Looks to be in decent...although original...shape, and isn't leaking oil.  Seems to only have one wire going to it, and then that wire joints a cluster of wires that goes up to the side of the doghouse opening, just like Dave's picture, but towards the front of the compartment.  In the back there is a plug in the oil galley, so I'm guessing this is an alternative location.

Anyhow, I followed those wires, right to a big relay, marked with the same GM part number as Dave's illustration, 15528707.

Which is right next to an even bigger relay that is somehow part of the AIR system.

Anyhow, found it...now I just have to figure out how to troubleshoot it!  I suppose I could replace the sender and the relay, but I hate replacing things that I'm not sure are broken.

Anyone have a clue as to how to test the relay to see if it is good?  The sender seems to be good, since it sends the signal to my dash meter to read between 60-80 psi...although it tends to either read nada when turned off, and a steady 80psi (just under) regardless of RPMs.  The meter only goes up to 80.

And if I wanted to bypass the safety switch part of the relay, which wire would I either ground or send to 12 volts?

Kev

I may have just answered my own question by typing in GM 15528707 on Google.

This is from a Barth owner's website:

"Those of you with late 80's Chev chassis will have a "hybrid" fuel system.  (Mechanical fuel pump and carb but also an electric pump in the tank.)  The pump is run by the fuel pump relay GM 15528707.  (see the 1996 Chev Motor Home guide Appendix 7-7 page 7-44 to 7-46) 

The relay has 2 functions:  it supplies power to the fuel pump during cranking and while running but shuts off if oil pressure is lost. Also it supposedly has a delay timer to cycle the pump for 5 seconds prior to startup.  (This, and the color coding for the relay, from page 7-46)

Bad news:  this  relay is required for engine operation, prone to failure, the part is not available anywhere I know of, and the relay diagram is vague about which wire does what inside the relay.

Good news: it's just a standard single pole (5 wire) relay with a timer inside. 

My Barth was slow to start after sitting due to dry carb bowl.  I have manual fan switches to run after shutdown to reduce heat soak but carb still needs priming.  Inspection of the relay (a tight fit under the forward left side of the doghouse near AC compressor and too tight for pics, sorry) revealed an empty relay case attached and another relay hanging from the wires.  My relay did not have the 5 second cycle working.  Search for replacement was dead end.

To take care of both problems I replaced the relay with the generic 5 pole type (same as the headlight relays, fan switch relay, etc.)  I also added (dashed lines in drawing) a normally open switch to trigger the relay for manual priming.  After sitting for some time, I hit the prime button about 15 sec and the engine started promptly!

If relay 15528707 fails, you'll need this info...
The black and dk blue wires are interchangeable.

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I happen to have a spare 5 pole relay from my headlamp troubleshooting from a while back, so I might just go ahead and try this!

If his wire colors are correct, it even looks like I could directly bypass this thing in a pinch where he added in a priming switch, and the priming switch isn't a bad idea either!

I'm gonna try it!

Kev

For Reference:
You do realize that all this information is from the free book (Member Area, Manuals, Diagrams & Tech Info, scroll down to chassis section and select Chevy/GM P-30 Service and Maintenance Manual).   Both I and the Barth write up are referrencing pages in that book.

Dave

I was thinking about this and you could be running out of  timing advance or be having some other distributor problem...even timing chain stretch could cause vapor lock like issues....I remember you were playing with your timing a while back.

I only advanced the timing a hair, enough to raise the idle from 700 rpm to around 900-1000, then dropped it back down with the idle screw.

While its possible, I doubt I have any significant timing chain stretch yet at 110K miles.

And it ran great at the new timing settings all the way from St. Marys, GA, down through Jacksonville, FL to I-10, and all the way across the country to about half way through Texas.  Then it started the vapor lock symptoms again, and I drove the Jeep to an auto parts store...the electric fuel pump that I had just installed a year ago had stopped working, so I bought another fuel pump, installed it, and it seemed to fix the problem.  Then we were good all the way to Tombstone, AZ.  It started this vaporlock crap again once we about 80 miles away from Tombstone and back on I-10, on our way to Safford, AZ.

The reason I'm zeroing in on the relay is that I don't think it was the fuel pump...I think its the relay on its way to failure.  My reasoning is this.  When in my sister's driveway troubleshooting the fuel delivery problem for the genny, I removed the fuel pump from the tank to double check which pickup tube was which.  Then of course, once I reinstalled it, I had to test it.  I had Patti turn the key, and there was no fuel flow.  I had her turn the key again and start the engine, and still no fuel flow from the electric pump.  The third time, without touching any wires or anything, the pump started flowing fuel. 

When it went out in Texas, I figured maybe the pump went bad, installed a new one, and we were fine until Tombstone.

Then it crapped out again, and there is no way another new fuel pump went out.  Gotta be the relay or connections.

Kev

From the Service book:
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There can be a bit more to the original circuit than you may be aware of.    Barth drawing is a variation of this.  I believe the Barth approach removes the 5 second "prime" circuit contained in the original relay.

Dave

Kev i have found that when you have trouble with anything more than twice Eliminate all of its components . I would install a holly fuel pump back near the tank (should be as low as possible)  Install a common H/L relay with a switch direct from batt source with its own wireing fused 30A . If problem occured again turn on aux pump this will cure loss of fuel and eliminate any balky orig switches & relays . To me to keep on trucking is the goal fixing malfunctioning parts is not important They can work or not work that is there option but i am not stopping to find the problem  Frank!

Ruh Roh Shaggy!

Apparently the Barth is wired quite differently from ours!

I hooked the 5 pin relay up just like the drawing from the Barth website, using jumper wires from the pink wire to the blue wire, up to an unused toggle switch on my dashboard.  Made sure that switch was OFF.  Turned on my chassis power, then turned the key to "on".

And the relay immediately engaged the starter in the "on" position!  Not even in the "start" position, but "on"!  Turned off the key...CRAP!!!

Checked for any shorts, maybe spade terminals touching, and nada.  Tried it again, and same thing!  Starter engages in the "ON" position!

Okay...something is screwy!

The relay I have has the exact same pin layout as the Barth drawing, and if I recall from my headlight project last winter, it was a leftover universal headlight/foglight relay, rated at 30 amps.

So something isn't translating from the original fuel pump relay to the 5 pin headlight relay...so I must have one or more wires plugged into the wrong spot/s.

Any of you electrical gurus have a better idea of how to wire in a 5 pin headlight relay into the system that will make it work similarly to the relay diagram that Dave just recently posted?

Unfortunately the relay I used doesn't have a diagram printed on it, or else I might be able to figure it out myself.

Thanks guys!  Stuck in the desert till we fix this...lol!

Kev

See reply 19 before you let the smoke out of all the wires. Obviously you supplied power to the purple wire wich energizes the starter  ! You want to go from Pink to your switch thenfrom the switch to the tan and white That will eliminate all when switched on to run pump (if the switch is good)  Frank

okay...might have sort of figured something out. 

I pulled the relay to look at it more closely, and guess what?  The engine won't start at all without a relay in place.

Anyhow, I looked at the relay carefully, and maybe its just an odd bird relay?

Unlike all the diagrams I found for 5 pin headlight relays, this one on its own diagram doesn't have an 87 and an 87a...but rather it has 2 87s connected to each other at all times.  86 comes into one side of the coil and 85 into the other.  From the coil is a line that goes to switch 30...which closes the circuit to 87------87

All the other relay diagrams I've seen toggle between 87 and 87a, not leaving them connected together.

Anyone seen this before?  I can't even find a similar diagram online to show you what I'm talking about.

Kev

So yep Frank.  Since pin 87 is constantly connected on this relay to pin 87 (which on every other relay I've ever seen is an isolated 87a), then the pink ignition wire is supplying 12 volts to the purple wire which goes to the starter relay.

Geesh!

I'm going to go check my electrical box and see if I have any other relays in there...

Kev

THIS is what the diagram on the relay I'm trying to use looks like:

Image no longer available

Except 87b is marked simply as 87, as is the other 87.

And on the relay diagram, the 86 is on the top of the coil, and the 85 is below the coil, but I don't think that part matters.

Anyone think I can make this work, even if I have to jump or connect a wire or two?  At this point I just want to get it running and the fuel pump running...I don't care a hoot about the oil pressure safety shutoff for now.

Kev

Supplying battery power (fused) to the tan/white wire will run fuel pump irreagardless of anything else ( if wire from relay to pump is good)  Run it thru a switch if you want the pump to shut off You can also incorporate a pilot lamp to show pump is on .  Frank After following caution These instructions do not care about relay type The relay can be thrown away . But to use pump it would have to be turned on >

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Yep...I figured as much while I was pouring over the diagrams, and the differences between a standard headlight 5 pin relay, and the one I found in my drawer.

Turns out the one in the drawer was the original that was under the dash of the RV...and the one I installed, not knowing any better, was a standard relay.

I switched them out, and still no power to the fuel pump.

So I figured, hey...tan/white is direct to the fuel pump, and pink is hot when the ignition is on, right?  So I reconfigured the wiring so that my toggle went to the tan/white and the pink.

Started right up, but still no juice to the pump!

Turned it off, and hit the toggle with the ignition key in the on position.  Toggle lit up, but no juice to the pump.

Then I tried to restart it, and while the engine was turning over, it wouldn't start!

what in the world? 

I sprayed electrical parts cleaner into the carb, and she started right up, and stayed running as long as I was spraying, but as soon as I stopped spraying, the engine would die.  I pulled the fuel line off the carb, and turned the engine over...no fuel flow AT ALL!!!

So apparently the mechanical fuel pump has decided to give up the ghost!

Might be that the mechanical pump was dead on the way here, and I was running on just the electric pump!

Anyhow, the electric pump isn't getting juice even with the proper relay, bypassing it still doesn't get it powered up, and now the mechanical fuel pump has pooped the bed!

At least I have a brand new mechanical pump waiting to be installed, still in the box and plastic.  So that is the first thing I'll be doing tomorrow.  I put it off this long because the old one was working, and in order to get to the mechanical fuel pump on our rig, you have to remove the Safe-T-Plus steering stabilizer...so I put it off.  Can't put it off now!  Gonna have to bite the bullet and put it in tomorrow.  Even if the electric pump isn't running, the mechanical pump should still pump gas at idle.  Not sure if the converse is true though...not sure an electric pump will push past a broken mechanical pump.

In any event, as far as the electrical fuel pump goes, I have 2 spares in case this new one is shot...but I may very well have blown a fuse when I wired in the wrong relay earlier today.  I'll check the fuses first before writing off the electric pump...and I'll test the pump with direct 12 volts.

So after figuring this all out, I decided to drive the Blazer into town 30+ miles away to see if I could get a new fuel pump relay in the original configuration.  Went to Napa, Autozone, and O'Reilly's, and the Barth website spoke true...apparently the GM relay 15528707 is obsolete and no more!  Unobtainium!!!

They couldn't even cross reference it, so I'm stuck with a rewire.  I took the cover off the original, and you could see the black burns all over the circuit board.

So while I was there I picked up more zip ties and a 4 pin 30 amp relay just like I used when I redid the headlights last year.

My plan is to install the new mechanical pump, then look for a blown fuse to the electric pump.  If its just a blown fuse and the pump becomes operational, we're all good to go.  If its not a blown fuse, then I'll be running a brand new 10 gauge wire all the way back to the fuel pump, tie it into the relay, and have the relay triggered by the pink 12 volt ignition wire.  Another 10 gauge wire will go right to battery with an inline fuse.  I'm done playing around, and I'll rewire the damn thing just like I did the headlights!

Even if it is a blown fuse, I'm still going to run the 10 gauge wire I decided, but instead of tying it into the pink wire, I'll run it to the toggle switch on the dash, tie the toggle into the pink wire for a 12 volt source to trigger the relay, and another 10 gauge wire going to battery.  That way, if a fuse blows or the electric fuel pump decides to get finicky again, I'll be able to hit the toggle and bypass everything, forcing it to run with direct 12 volt current.

I might just go ahead and rewire it to pink anyway, regardless of what I find out about fuses.

Gonna be a long knuckle busting day tomorrow!  I'm sure there will be many curses as well...

Kev

Couldn't you use a jump box back at the electric pump before you run wire? Utilizing short scrap pieces of wire and see if it even works, kinda like a bench test minus the bench and comfortable seat  :). Someone monitor the jump box and fuel, the other cranking the motor. This is just to narrow down the issue.

Kev it is past time for a fuel pressure gauge You are doing too much shooting in the dark. With your hot wire the pump shoud have run if all wireing is good .And switch is good electrical tester should verify  or go direct without switch Pink is only hot with ign on  Also better check for fuel in the oil sump if you suspect mechanical pump failure . Replaceing mechanical pump is not a waste of time if it is old A new one is better . Frank

Not a bad idea, but I am now intimately familiar with the top of my gas tank and the electric fuel pump...lol!  I have two spares, both take offs but I know the first one was running when I removed it.  Not so sure about the second one, but it was less than 2 years old...and the one on the rig is only a month old!  I'm going the whole nine yards this time, just like with the headlights.  I'm sick of fixing the same thing over and over...time to fix it once and for all!

Dang that military truck is looking better and better!  Nothing frail or fragile about those!

Kev

Good point Frank about the diaphragm it could be bad and letting fuel go by. THANKS FOR REMINDING ME OF ANOTHER PROJECT THAT NEEDS TO BE DONE  D:oH!

Thanks Frank.  I'll check the oil to see if it smells like gas or has lost viscosity.

I have an inline fuel pressure gauge, but its plastic so I didn't want to leave it in place...I use it to test the system, then remove it.

When I went through all this crap last year and replaced the electric fuel pump and the carb with an Edelbrock, I used it to test the flow, and it was perfect.

Gotta be a fuse as far as the electric pump goes, or the wiring itself.  Even direct there was no power to the pump.  And the mechanical pump has definitely died.  Cranking the engine, even with a dead electric pump, fuel should have poured out of the gas line when I took it off the carburetor.  But nada, nothing.  Not a drop.

I'm taking the hill tomorrow.  All out, no holds barred, right up the hill with a primal scream, charging the enemy machine gun nest.  Well, maybe not that dramatic, but I'm going to do it right, once and for all.

The headlights were a valuable lesson for me.  Either dicker around with something peicemeal, or go for it all the way.

Kev

Okay.  So I wired it up to the correct relay, but using the diagram from the Barth site.

Turned the key to On, and hit the toggle.  Nada.  Checked the fuses, and the 20 amp fuse marked Choke was blown.  Replaced it, hit the toggle, and the electric fuel pump ran long enough to start the engine, then blew the fuse again!

According to the wiring diagram Dave posted, the dark blue wire, which powers the relay, is in the same circuit as the choke, oil pressure switch, etc. 

So, what am I doing wrong?  How should I wire up this standard 5 pin relay so it powers the pump but doesn't blow the fuse? 

I'm about to install the new mechanical pump, so I'll check back later this afternoon or this evening to see what you guys have to say.

Thanks!

Kev

Blowing the fuse indicates a dead short somewhere to ground. How did it quit the first go around with the old relay and wiring? Perhaps a short in the wiring from the electric pump up to where you are tying in now? Is the fuel pump new?
That's where I would start to look. Hm?

Well Kev First I dont think 20 A is high enough for a elec fuel pump . But you need to see if there is a short or an excessive draw Since i dont know if you still have the electric choke That wire may be lying loose near carb . Finding a short is not easy . Do you have any way of checking draw on curcuit ? This is the reason i reccomended a New separate curcuit for the fuel pump (run a new wire to the pump eliminate the old one ). Fused 30 A and switched with a New switch Then if you blow the fuse you know its the pump drawing too many amps . Frank

Aside from making sure you have adequate power make sure of a good ground. When I had my s-blazer I was going through fuel pumps like crazy. Turned out it was a bad ground  causing the pump to pull too many amps then burn itself out.

Oldrockandroller, called them and a few others that had them listed, and they are out of stock.

Thanks Frank.  Could be the whole problem.

Since the relay is working to start and keep the engine running, I'm thinking of just forgetting about the 20 amp choke fuse, running a new wire for the choke off the hot wire of the distributor, and then installing the new 4 pin 30 amp relay specifically for the fuel pump.  Still deciding if I want to run a lead from the pink wire to the proper pin on the relay to power the relay any time the ignition is on, or else do the same thing, but run it to the lighted toggle so I can see at a glance with a dummy light that the electric fuel pump is getting juice.  In either event, I'm going to run a new 10 gauge wire right to the fuel pump, then to the 30 pin of the new relay.  Then 10 gauge wire right to battery positive with a 30 amp inline fuse, and the other pin to ground with 10 gauge.

That will certainly solve the problem once and for all!

I had a pretty easy time with the mechanical fuel pump replacement today.  The hardest part was cleaning off the old gasket, since its not exactly easy to get to.  Removing the Safe-T-Plus steering stabilizer was easier than I thought it would be, so that gave me easy access to the pump from under the rig.

I used high temp RTV sealant on both sides of the new gasket...and on the pipe plug for the pushrod.

OMG the pushrod is WAY bigger than the one on the Dodge 413 we had in the Ark!  I held it in place with wheel bearing grease when putting in the new pump.

Took all of 3 hours to do the job, and that was with lots of breaks.

WAY smoother and easier than I thought it would be!

No gas smell in the oil at all, so that's a good thing! 

Tomorrow is wiring day, so if any of you have any better ideas than my direct wire through a relay idea, let me know before tomorrow morning...lol!

Thanks again everyone!

Kev

Thanks jkilbert!  I'll double check the grounds at the pump while I'm at it, but they were pretty solid when I recently checked it.

The pump was running briefly before the fuse blew, so I know it works...and running the new 10 gauge power wires should eliminate any electrical problems in the mix.

Only thing in the diagram that has me confused is that the blue wire, the circuit that keeps blowing, goes to the oil pressure switch as well...which I could care less about...and it says "ignition fused"...as well as the choke.  The pink wire comes from ignition though.  So I'm guessing this has something to do with the timer of the original relay?  It starts and runs even with the choke fuse blown...cuts out because the electric fuel pump dies, but will run on electrical parts cleaner as long as I keep spraying it in the carb...lol!

Things are coming together.  I got the mechanical side of the fuel delivery done today...tomorrow, its the electrical!

Let me know if you guys see something I'm missing!

Kev

Circuit description (Barth version):
1. When you place key to RUN prior to starting, no voltage to relay coil because oil pressure safety switch is not made yet.  You can use the PRIME switch to pressurize the line prior to start.
2. When you go on to START, power is provided to fuel pump over NC (87A) contact to pin 30.
3.  Once engine starts, oil pressure safety switch closes and allows power to relay coil blue wire (pin 85) from ignition run switch.  When you release key from START to RUN, power stays applied to relay coil as long as A) engine is running (oil pressure safety switch closed) and B) ignition switch is in RUN.  With coil energized, power for fuel pump is provided by pink wire to NO (pin 87) to pin 30.
4.  If you are in an accident and the engine stops running, the oil pressure switch opens up shutting off the fuel pump.  That is the safety part of the oil pressure switch

There is most 2 oil pressure switches installed.  The small one (2" long and 3/4" dia) with 3 terminals is used for the idiot light and fuel cutoff switch.  The larger "can" type (like shown in your other oil pressure switch posts for you toad) is used for an oil pressure gauge. 

In original design:
Power to fuel pump when key in START is provided buy purple wire from starter solinoid
Power to fuel pump when key in Run is provided buy Pink wire from ignition switch

Choke fuse is only used for relay coil and choke (not pump power).  The choke fuse would be a ignition switched circuit though.   These ciruits should be low amperage.   Nothing like the high fuel pump current.

Barth circuit:
Power to fuel pump when key in START is provided buy purple wire from starter solinoid (again pin 87A to 30)
Power to fuel pump when key in Run is provided buy Pink wire from ignition switch (87 to 30)

Either they retained the original circuit OR they moved the input to the oil pressure switch from the choke fuse to the ignition switch.  Not clear from their drawing.

Dave

Thanks Dave!  That clears up a lot, but doesn't explain the fuse blowing, which I still haven't figured out.

Regardless, I'm going to run new wires via the new relay.  Leaning towards the toggle switch which is lighted...if the fuse blows, the LED goes out, and I know its not running...lol!  Light on, electric fuel pump running...no brainer!

That's tomorrow project!  Gonna rewire the choke to the ignition positive on the distributor, and the relay to the lighted toggle most likely.  That way I can prime it before starting, and then when started I know the pump is ON!

Kev

Today is the big day when I get the darn electrical fuel pump working on its own circuit through its own relay.

Since I won't have the oil pressure safety switch in the circuit anymore, I wouldn't necessarily recommend the way I'm going to do this to others, but in a pinch, if you own a P30 chassis motorhome and the fuel pump relay dies, hopefully someone can glean some useful info from my fiasco in learning how to make other relays work.

I'll let you all know how it turns out this afternoon.

Kev

So this is the exact relay I'll be using, a Novita RL44 40 amp unit:

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I decided to skip the toggle switch, since it will light up no matter what if there is 12 volts going to it.

Instead I'm going to keep it simple. 

The pink wire on the existing relay is 12 volts positive when the key is turned on.  I'm going to splice into this wire with 2 leads.  One will go to the electric choke, and the other will go to pin 86 on the new relay...that will energize the relay whenever the key is turned on...it will self prime without a toggle.

Right from battery, I'll be running a 10 gauge wire to pin 30 with an inline 30 amp fuse.

Pin 85 is ground, so I'll run a 10 gauge wire from there right to a good ground in the engine compartment.

Pin 87 is power out...I'll run a 10 gauge wire from this pin, all the way back to the electric fuel pump.

As long as the pump is still good, this should work out nicely!

Kev

I have a question. Nobody here has brought up why you have to prime it. This is a carburetor, not fuel injection. The carburetor bowl will have more than enough gas in it to start the vehicle and get the oil pressure up to the point that the electric pump kicks in. BUT, Even if the carburetor was dry (another problem that should not happen) you have the mechanical fuel pump which will draw at least 10" of vacuum, more than enough to pull gas from the tank and fill the carb. Kevin, I don't think you need 10 guage wire and a 30 amp circuit for a fuel pump. I have not seen your pump but I have run some pretty serious race pumps and they didn't pull 20 amps let alone 30. You do not want to oversize the fuze on the circuit, that can be dangerous. It is supposed to blow before something goes up in flames and to blow a 30 amp fuse is a serious short. You can run the 10 gauge wire but size your fuse according to the draw of the pump, you want the fuse to go before the magic smoke gets out of the pump. I have heard that the magic smoke and the gas genie do not get along well. W% It seems like a lot of your testing is "turn it on and see what happens" testing. That is not good and can get real exiting. You really need to invest in a digital meter and a test light. I have been watching this carefully because I have the same issues but in addition I have the regulator leaking back next to the tank and I can't get to it without dropping the tank.

Hi Kev Looking at amp draw for fuel pumps most are rated @ 20 A Draw so a minimum fuse would be a 25 A . .I dont think 30 A is too much .  Also since GM only added these electric pumps for occasional  Vapor lock your veh should run ok on just the mechanical pump If all fuel lines and filters are clear . Did you try to to see how much fuel is being pumped by the mechanical pump? Should be at least 1 Gal a min  with a cold syestem . If not you have a plugged syestem or a leak drawing air  Frank

As far as the choke wire goes if it goes thru what appears to be a oil switch this is actually an oil temperature switch witch controls the electric choke when mine went bad it blew the fuse and the choke light stayed on in the dash had to search a marine catalog at pepboys to find a new one hope this clarifies something   Gary  By the way theres 2 switches on mine the single wire works the gauge the two wire is the one that works off of oil temp for the choke

Once again in the words of Stewie from Family Guy...VICTORY IS MINE!!!!!

There is a reason I don't play the lottery.  There are 3 wires going to the fuel pump, and one is obviously a ground.  So that leaves 2.  50/50 shot, right?  One is 12 volts to the pump, the other is to the fuel gauge.

They look the same and are the same color.  I snipped one, and turned the key...fuel gauge pinned.  Yep!  Not a lottery player!  50% chance of winning, and I still lost...lol!  I hooked that wire back up, and then clipped the other wire and taped it off.

I ran fresh 10 gauge wire to the pump.  I sacrificed my oldest 10 gauge extension cord to come up with the wire in the middle of the desert.

I tied it into the other wire of course, ran it up high along the frame rail with lots of zip ties, and right to the engine compartment.

To make sure the pump still worked, I had Patti stand near the tank and put the new wire to battery hot...BINGO!!!  Pump running!

Then it was time to install the new relay.  Found a good place to screw it down, added all the spade terminals, and wired everything in.

I didn't have a fuse holder, so used spade terminals right to a 30 amp fuse inline with the wire to the pump.

System test!  Chassis power on, no juice to the pump.  Key on...power to the pump!

Choke works great attached to the spliced lead.

It works!

Victory is mine!!!

Kev

Sounds great!  Congratulations!   :)clap  sometimes things DO work out.
Neil and Shelley

That should totally eliminate the vapor lock from now on.  I also backed the timing off a bit and set the idle accordingly, and then reset the idle power mixture screws according to Edlebrock specs.

Should run like a top again!

Kev

Road test report:  Fixed!!!

All power restored with no vapor lock.  Drove it 35 miles with Patti following me in the Blazer, and no problems at all...runs perfect again!

Tomorrow we'll see how she performs pulling the Blazer.  I have it all hooked up now, but we are pulled over for the night in a vacant lot in Safford, AZ.  Only pulled it about 400 yards after hooking it up, but it seemed to pull it just fine.

We'll see what tomorrow brings!  100 miles to our next stop at Tonto National Forest, up some pretty steep climbs.  That will be the real test.

Kev

Final road test report, pulling the 4800lb K5 Blazer:

Outstanding!

Even up the steep grades on Route 70 and Route 60, she pulled the Blazer no problem, stayed nice and cool, no vapor lock, and the fuel gauge needle wasn't bobbing like crazy anymore!

Also seems to be getting better gas mileage...probably since I don't have to floor it anymore to make the hills at 45mph.  I only had to open the secondaries a couple of times on some really long grades.

Topic solved, and problem fixed!

Kev

Glad to hear Kev.

Dave

Hi all I have a 1987 fleetwood pace arrow P30 chassis with a 454.  I want to cut a hole in the floor to look at the fuel sending unit and make sure the tank is good before I install new laminate flooring. is the sending unit anywhere on plans as to where it would be located under floor?  I'm not sure if my fuel gauge is reading correctly and am installing custom dash with gauges in it so want to have a look.  any ideas or help???

If you get under the rig and look on top of the fuel tank, you might be able to see the wire for the sending unit and ohm it out. Check my post on inspecting my fuel cell on p30 chassis. And also use the search box and there's a lot of info on that.

Hey New guy, welcome to the forums..
I think if you do a forum search for fuel relay you may find someone has already posted the info you are looking for.  Give it a shot!


CMM500

Is there a diagram that identifies exactly where to make a hole in the floor?  No.  You will have to use the OEM diagrams at GM Parts East (http://www.gmpartseast.com/oem-chevy-parts.html (http://www.gmpartseast.com/oem-chevy-parts.html)) to see what the tank looks like then get under the rig to get a visual picture of where the sender would be located.  Then carefully cut away

Dave

Not sure if our tank is standard, or all P30 tanks are alike...but on ours, the sending unit is dead center of the fuel tank.  So if you measure where your tank is, you should be able to get close with careful measurements transfered to the inside.

Kev

Primer switch, fuel pump run on start, oil pressure switch cutoff?  You guys do realize you keep circiling this drain right?

(https://www.classicwinnebagos.com/forum/gallery/8/1-091020055745.png)

About five years ago you wrote...   

>then reset the idle power mixture screws according to Edlebrock specs.

I have a 1985 Fleetwood with a P30 454 and a Edelbrock that needs work...   
Where did you inf the specs?

And did you ever find a source of the GM 15528707 relay?  Even a dead one?
BTW, the AC-Delco 212-298 is the same relay.

Mike

Holy old thread resurrection...lol!

Everything I learned about the Edlebrock came from the owners manual that came with it and the DVD that came with it.  It has been so long since I tinkered with it I couldn't tell you more about the adjustment procedures.

As far as the AC Delco part number, that is NOT the correct relay.  And the GM relay is unobtainium. 

If you are having issues with the relay, you will need to do what I did and follow the diagram Dave put up to wire in a new generic relay.  It works, it works well, and it only costs about 20 bucks to make the permanent repair.

Kev

Kev, Did you end up rewiring your desert fix to match up with the generic relay, cause in one post you indicated that diagram did not work for you... I have the same itasca you have and dont want to fry my starter.

Yep.  By following the diagram in this thread, it worked and worked great!

Kev

Did it today and its working like a charm too, thanks so much to Dave, Barth, and You.

Quote from: ClydesdaleKevin on January 21, 2014, 09:28 AM
That should totally eliminate the vapor lock from now on.  I also backed the timing off a bit and set the idle accordingly, and then reset the idle power mixture screws according to Edlebrock specs.

Should run like a top again!

Kev

The diagram isn't popping up for me. Where can I locate this?
Also to be clear you're saying the 5 prong relays we find in store today won't work for us? Even if it has the numbers 86, 87, 87a, 85 and 30?

(https://cimg1.ibsrv.net/gimg/www.f150online.com-vbulletin/624x600/picture_php_pictureid_20636_c5866dd4ebd743776abb5bd8fc2d0370969f5af8.jpg)

Is this for the fuel pump?

Fuel pump relay. That's what the topic is about.
I replaced all the images with working ones.

 !-! Looks like the headlamp relay circuit instead of the fuel pump relay.  !-!

So confusing because the diagram talks about head lights. There's no fuel pump labeled on the diagram.

I believe, if you read the text, it says that the switch pin configuration should be "like" that.

Also, scroll down the one Kevin posted.  I don't know anything about electrical stuff myself,  I just tried to fix the photos. Lol!

 :D thank you!!

I sent a message to Kevin, the OP, to help shed some light on this.  Hopefully, he will.

I know I read one of his replies as to what relay he got, and that he did get it fixed. So, something must've gone right!

Ive been on this all day!
I'm coming close I believe.
I need a RL 44 relay (4 prong)
I then need the installation socket part number RS40(where the 4 prong relay will plug in to.)
THEN based off of where 86,30,85 and 87 line up with Is where I wire in the wires.
Adding in the inline fuses easy! (He did use 30amp fuses right)
The part that I am stuck at is where he splices the pink wire to go to 86 and the choke.
I'm not sure but I believe he clipped the pink wire And added a splice connect which had two separate wires connected to the other end which one went to the choke and one to 86.
I'm hanging out in a Walmart parking lot until I get this fixed. I'm smack dab in the middle of all the parts stores and Lowe's so I hope he or anyone can chime in!
Been here since yesterday!
I will get my 10 gauge wire from Lowe's.

Quote from: My.winnebago.tribe on October 09, 2020, 04:12 PM
Ive been on this all day!
I'm coming close I believe.
I need a RL 44 relay (4 prong)
I then need the installation socket part number RS40(where the 4 prong relay will plug in to.)
THEN based off of where 86,30,85 and 87 line up with Is where I wire in the wires.
Adding in the inline fuses easy! (He did use 30amp fuses right)
The part that I am stuck at is where he splices the pink wire to go to 86 and the choke.
I'm not sure but I believe he clipped the pink wire And added a splice connect which had two separate wires connected to the other end which one went to the choke and one to 86.
I'm hanging out in a Walmart parking lot until I get this fixed. I'm smack dab in the middle of all the parts stores and Lowe's so I hope he or anyone can chime in!
Been here since yesterday!
I will get my 10 gauge wire from Lowe's.

Did you figure this out yet?  It has been a LONG time since I owned that rig (we now have a diesel pusher)...but I did get it working.  And working well for years.  If what you've seen doesn't work for you, keep looking through my old posts about fuel pumps, relays, Barth, etc in the search.  The information IS there.

Kev

Keep in mind that when I wired mine up and it actually worked, I totally bypassed the oil pressure/fuel pump switch.  I know it is a safety hazard if you crash, but we needed our RV to work, period.  Hope that helps.  Somewhere here in the archives of my posts are clear instructions, including pictures, of how I actually did it.  I can't help you much from memory alone though, since it was a long long time ago.

Kev

This is the post where you put your solution though correct? I can just use this thread?
Can you maybe read where you spliced the pink wire and added it to the carb and 86 and tell me if this sounds right to you...
Splice the pink wire and add a splice connect and insert two wires to the other side to run to carb and 86.
I'm okay with bypassing the switch as well

Quote from: My.winnebago.tribe on October 09, 2020, 04:12 PM
Ive been on this all day!
I'm coming close I believe.
I need a RL 44 relay (4 prong)
I then need the installation socket part number RS40(where the 4 prong relay will plug in to.)
THEN based off of where 86,30,85 and 87 line up with Is where I wire in the wires.
Adding in the inline fuses easy! (He did use 30amp fuses right)
The part that I am stuck at is where he splices the pink wire to go to 86 and the choke.
I'm not sure but I believe he clipped the pink wire And added a splice connect which had two separate wires connected to the other end which one went to the choke and one to 86.
I'm hanging out in a Walmart parking lot until I get this fixed. I'm smack dab in the middle of all the parts stores and Lowe's so I hope he or anyone can chime in!
Been here since yesterday!
I will get my 10 gauge wire from Lowe's.

Did you figure this out yet?  It has been a LONG time since I owned that rig (we now have a diesel pusher)...but I did get it working.  And working well for years.  If what you've seen doesn't work for you, keep looking through my old posts about fuel pumps, relays, Barth, etc in the search.  The information IS there.

Kev

Quote from: Oz on October 09, 2020, 11:53 AM
I sent a message to Kevin, the OP, to help shed some light on this.  Hopefully, he will.

I know I read one of his replies as to what relay he got, and that he did get it fixed. So, something must've gone right!

Once this is resolved, someone needs to put up a "sticky thread" with all the info, since this is such a common problem with the old P-30 chassis, and the factory relay is no longer obtainable.

Kev

Quote from: My.winnebago.tribe on October 09, 2020, 05:58 PM
This is the post where you put your solution though correct? I can just use this thread?
Can you maybe read where you spliced the pink wire and added it to the carb and 86 and tell me if this sounds right to you...
Splice the pink wire and add a splice connect and insert two wires to the other side to run to carb and 86.
I'm okay with bypassing the switch as well

These two posts highlight exactly where I fixed it, and how:  "So this is the exact relay I'll be using, a Novita RL44 40 amp unit:
(https://www.classicwinnebagos.com/forum/proxy.php?request=http%3A%2F%2Fwww.novitatech.com%2F%3Fq%3Dsites%2Fdefault%2Ffiles%2Fstyles%2Flarge%2Fpublic%2Fproducts%2Fimages%2FRL44-Diagram.jpg&hash=5d0ad62dda0f4f93547900e7b8aebd45e1e0b995)




I decided to skip the toggle switch, since it will light up no matter what if there is 12 volts going to it.

Instead I'm going to keep it simple. 

The pink wire on the existing relay is 12 volts positive when the key is turned on.  I'm going to splice into this wire with 2 leads.  One will go to the electric choke, and the other will go to pin 86 on the new relay...that will energize the relay whenever the key is turned on...it will self prime without a toggle.

Right from battery, I'll be running a 10 gauge wire to pin 30 with an inline 30 amp fuse.

Pin 85 is ground, so I'll run a 10 gauge wire from there right to a good ground in the engine compartment.

Pin 87 is power out...I'll run a 10 gauge wire from this pin, all the way back to the electric fuel pump.

As long as the pump is still good, this should work out nicely!

Kev"

And:  "Once again in the words of Stewie from Family Guy...VICTORY IS MINE!!!!!

There is a reason I don't play the lottery.  There are 3 wires going to the fuel pump, and one is obviously a ground.  So that leaves 2.  50/50 shot, right?  One is 12 volts to the pump, the other is to the fuel gauge.

They look the same and are the same color.  I snipped one, and turned the key...fuel gauge pinned.  Yep!  Not a lottery player!  50% chance of winning, and I still lost...lol!  I hooked that wire back up, and then clipped the other wire and taped it off.

I ran fresh 10 gauge wire to the pump.  I sacrificed my oldest 10 gauge extension cord to come up with the wire in the middle of the desert.

I tied it into the other wire of course, ran it up high along the frame rail with lots of zip ties, and right to the engine compartment.

To make sure the pump still worked, I had Patti stand near the tank and put the new wire to battery hot...BINGO!!!  Pump running!

Then it was time to install the new relay.  Found a good place to screw it down, added all the spade terminals, and wired everything in.

I didn't have a fuse holder, so used spade terminals right to a 30 amp fuse inline with the wire to the pump.

System test!  Chassis power on, no juice to the pump.  Key on...power to the pump!

Choke works great attached to the spliced lead.

It works!

Victory is mine!!!

Kev"

Here is the missing image, since it didn't copy and paste.  (https://www.classicwinnebagos.com/forum/proxy.php?request=http%3A%2F%2Fwww.novitatech.com%2F%3Fq%3Dsites%2Fdefault%2Ffiles%2Fstyles%2Flarge%2Fpublic%2Fproducts%2Fimages%2FRL44-Diagram.jpg&hash=5d0ad62dda0f4f93547900e7b8aebd45e1e0b995)

So to be clear, the pink wire needs to be spliced into two leads, with one lead going to the electric choke, and the other lead going to pin 86 on the new Novita RL44 4 terminal relay. 

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You need to run a wire direct from battery, with an inline 30 amp fuse, to pin 30.  You need to run a good ground wire from pin 85 right to a good chassis ground in the engine compartment...and finally, you have to run a wire all the way back (10 gauge preferably) from pin 87 to the positive wire on your in-tank fuel pump.  It is that simple.  If you connect to the wrong wire at the fuel tank, the only thing bad that will happen is your fuel gauge will peg.  So switch the wire to the correct one.  Problem solved!  (Disclaimer:  This bypasses the oil pressure safety switch which is designed to shut off the fuel if you are in a crash...so use this formula at your own risk).

Kev 

Topic is a 'sticky', as suggested.

Quote from: Oz on October 09, 2020, 11:55 PM
Topic is a 'sticky', as suggested.

Thanks Mark!  I think this will help a lot of folks.  Although it seems the person this is intended for went with the inferior "toggle switch" method on another post...lol!

Kev

Mine is located in the doghouse just forward of the AC compressor on the bulkhead against where your foots sits on accel pedal...

https://www.dropbox.com/s/e78a5103ygrztya/20180513_032855%5B1%5D.jpg?dl=0

hello,

I am new to this forum and have found alot of the information helpful and have gotten this far so here it goes

1991 Chevy P30 454 7.4 TBI Fleetwood Bounder
we have done alot of work to this RV since last year new brakes, new fuel pump, all new gaskets etc on the TBI, water heater, even fixed the hydro boost that was fun (i call it the octopus) etc. it was running fine last year and through the winter we start it up and the week before Easter we started the RV and moved it and the following wknd after loading it up we went to leave and would not stay running.

It starts and runs for aprox 20 sec and shuts off.  turn the key off and back on and it starts but will not start unless you cycle the key.
so the following have just been replaced
Oil sending unit (now the oil pressure gauge is moving LOL)
new O2 sensor
fuel pump relay (just an FYI we just found and add'l access panel on the carpet at the top of the engine hole within the cab we cut the carpet and was able to access the relay)
    ****now we found that when the relay was jumped the vehicle continued to run so we got a new relay put in and such a disappointment to find it still does the same thing.  starts and shuts off after 20secs

looking for suggestion, help anything would really love to get this back up and running again.
the good news once this thing is running she is a beast was running and sound good it really gets up and goes.

any help or diagrams for the fuel and wiring system would be AWESOME.

thank you look forward to hearing back

Mary
  :)

ok so we finally found the fuel pump relay. that didn't fix the issue.   but again when we jump the relay it stays running. 
does anyone know where the fuel pressure regulator is on these beasts????
1991 chevy p30 bounder 7.4 tbi

The fuel pressure regulator is part of the TBI unit itself. Can be seen between both injectors with several allen bolts. I would suspect the oil pressure switch is at fault. Also I'd replace the 'coolant temp sensor'. It is in the intake manifold just below the T-stat housing facing forward. Keep us up to date.