Classic Winnebagos & Vintage RVs

Topic Boards => Chevy - GMC Chassis => Topic started by: My.winnebago.tribe on October 07, 2020, 07:19 AM

Title: Replaced in tank fuel pump and still not working
Post by: My.winnebago.tribe on October 07, 2020, 07:19 AM
Hey all!
If any one could help it would be great!
We're actively traveling and constantly experiencing fuel delivery issues!
Our rig keeps shutting down when giving it a lot of gas or in town driving after getting off the highway in the middle of the road sometimes! N:(
OH and to get it started I HAVE to pour gas into the carb and close the choke manually or else it just cranks and cranks and cranks AND cranks.
I have all brand new pumps mechanical/electrical.
All brand new filters In carburetor and my in line fuel filter.
I have no gas leaks anywhere!
My electric fuel pump has to be the culprit here.
Fuel pump relay? Where could this even be? Hm?
Fuel pump fuse? Where could this even be? Hm?
Oil pressure sensor? I found this guy! :)clap
Where do I start?? ???
Title: Re: Replaced in tank fuel pump and still not working
Post by: Oz on October 07, 2020, 10:58 AM
Start at whatever is in-line in the fuel line path, be it a filter or pump, closest to your fuel tank and disconnect the line and momentarily have someone else crank the vehicle.

If fuel comes out, move to the next thing in line.
If not, it's either the in tank pump or power to it.

Caveat... that's IF you can get to the in tank pump.  You may have to disconnect the line just before your next item to check.
Title: Re: Replaced in tank fuel pump and still not working
Post by: My.winnebago.tribe on October 07, 2020, 11:38 AM

Will do... currently I have a board over the hole I cut in the floor to gain access to the fuel pump as I just replaced it the other day.
Title: Re: Replaced in tank fuel pump and still not working
Post by: tmsnyder on October 07, 2020, 04:28 PM
Fuel pump relay is near the driver but under the floor or in front of the firewall.  It runs the pump while cranking the engine, but shuts the pump off if there's no oil pressure. It's kind of a tough part to find.   If you open yours up you may find a wire trace burned out, in that case you can repair it by retracing the trace with solder or soldering in a jumper wire. 

There is a way to jumper two of the wires together in the connector to bypass the fp relay and make the pump run.  For trouble shooting, or emergencies on the road.  Not recommended for regular use though b/c if you get in an accident the pump will keep on pumping gas and there's a fire risk.

If it does turn out to be the FP relay and you can't find a replacement, you can also replace it with a regular relay and wire it to run the pump while the ignition switch is on and the oil switch is closed, but you'll have to add a momentary switch on your dash to power the pump while you crank.
Title: Re: Replaced in tank fuel pump and still not working
Post by: My.winnebago.tribe on October 09, 2020, 12:32 AM
Okay I found the relay and I got it to click with my jumper doing a bench test.
I never hear a click when it's installed though.
I also bought a new one that looked identical and had the same number 85,86,87,87a and 30.
Will it only click once the engine is running based off what your saying?
My in tank fuel pump DOES NOT turn on by simply turning the key to the on position I need to fully turn the engine over?

Can you explain the jumper part for me. I'm in a emergency. I need to get 8 hours away from here where I can settle down and fix this thing.

If you could actually explain or provide information on both methods that would be GREAT!
Title: Re: Replaced in tank fuel pump and still not working
Post by: tmsnyder on October 09, 2020, 09:02 AM
From this old post:  https://www.classicwinnebagos.com/forum/index.php?topic=8795.msg97714;topicseen#msg97714

One of the wires to the relay should be tan/white.   I'm assuming that's a tan wire with a white stripe.   That's the 12v wire to the pump.  It should be hot on crank, and hot on run/ign _if_ the oil pressure switch is closed.

If you run 12v to the tan/white wire you should hear the pump run. 

IF there was a problem with the circuit or pump, it may have burned out your relay.  It may be shorted.   So test with an ohm meter first.   And when you connect 12v, use a fused power source.  LIke a standard two spade fuse, those have 1/4" spade terminals you can connect with 1/4" female crimp connectors. 

In an emergency, you could 'hot wire' 12V to that wire and just have the pump run non-stop.   I would use a two spade fuse and 1/4" female spade connectors to connect a 12V wire direct from the battery, through the fuse, to the pump.   If you want to be fancy, put in a switch near the drivers seat.
Title: Re: Replaced in tank fuel pump and still not working
Post by: My.winnebago.tribe on October 09, 2020, 09:23 AM
Okay I can locate the tan wire...
When you say run 12volts to the wire what exactly do you mean?
Like connect it to a 12volt source?
You also state I use a fused power source. LIke a standard two spade fuse, those have 1/4" spade terminals you can connect with 1/4" female crimp connectors.
I would use a two spade fuse and 1/4" female spade connectors to connect a 12V wire direct from the battery, through the fuse, to the pump.   If you want to be fancy, put in a switch near the drivers seat.

Can you provide me images or links to what I need. I'm really logical and self taught but want to make sure I'm doing this RIGHT! It makes sense I just never purchased these items or done something like this.
Title: Re: Replaced in tank fuel pump and still not working
Post by: My.winnebago.tribe on October 09, 2020, 09:24 AM
I also read that entire thread and he did so many things I'm kind of confused as to what actually worked for him  Hm?
Title: Re: Replaced in tank fuel pump and still not working
Post by: tmsnyder on October 09, 2020, 09:43 AM
Hi, yes, so that circuit does a few different things that basically sends 12v power to the pump under certain circumstances.  Yes it's just a relay but there's actually a timing circuit in there that sends power after cranking the engine to start, briefly before killing it if there's no oil pressure. 

In your case you just want to power the pump in the tank by sending 12v to it via the tan/white wire.  (according to that diagram it's the tan/white wire, that is probably correct but I haven't verified it)

A standard fuse like this one is easy and cheap to include in your 'hot wire' of the pump power:  https://www.autozone.com/electrical-and-lighting/fuse-and-accessories/bussmann-fuse-bp-atc-15-rp/32348_0?rrec=true

And a standard 1/4" female spade connector like this can connect to the legs of the fuse, so you have fused power to the pump:  https://www.autozone.com/ignition/electrical-wire-connector/dorman-conduct-tite-blue-16-14-gauge-female-quick-disconnect/309450_0_0

Then wrap the 'legs' end of the fuse with black tape to protect from shorting out against anything.

B/c, if there's a short and you hot wire it without a fuse you could burn down your RV.  And since you are talking about your Relay being fried, it may very well be that your pump has failed, maybe it's drawing enough current to have fried the pump relay.   That's why I recommended ohming it first to see if it's shorted before connecting any power to it.

Good luck.
Title: Re: Replaced in tank fuel pump and still not working
Post by: tmsnyder on October 09, 2020, 09:57 AM

Crude schematic:

[Battery+]-----------fuse----------Tan/white wire----------fuel pump--------ground

The only part you are adding is:

               -------------fuse----------

This should run the pump continuously.   For emergency use only b/c all the safety things the relay does are not included.

But it will get you home. 

If the fuse blows then there's a problem with the pump or the wires to the pump.

Title: Re: Replaced in tank fuel pump and still not working
Post by: My.winnebago.tribe on October 09, 2020, 10:26 AM
To be clear...
I run a wire from battery (+) to female spade connector and this same spade connecter I connect the tan/white wire.
Correct?
Title: Re: Replaced in tank fuel pump and still not working
Post by: My.winnebago.tribe on October 09, 2020, 11:37 AM
My clip has the colors orange (Unless it's dirty and looks orange) with white strip, blue, pink, purple and green in order.
On the diagram on page 141 it shows colors in order as tan/white stripe, blue, pink, purple and black.
I'm assuming my orange/white is tan/white and my green is black as everything is in order.
When clipping the wire should I plug this thing back in or leave it unplugged?
Shouldn't I use the hot wire the pink 12 volt when doing my connections to the battery or am I mistaken?
I'm a novice so I got questions  :)
Title: Re: Replaced in tank fuel pump and still not working
Post by: My.winnebago.tribe on October 09, 2020, 12:07 PM
Ahhh I see. I think...
When disconnecting the plug and turning the ignition to on the tan/white wire will not have 12 volts but the pink one will because the pink is in circuit with the battery.
The tan/white is connected to the fuel pump and we want it to be connected to the battery so the 12 volts travel to the fuel pump.
The relay is supposed to do all of this by itself but it has failed so I am overriding it?
Am I right?
Am I turning into an electrician now?
Title: Re: Replaced in tank fuel pump and still not working
Post by: My.winnebago.tribe on October 09, 2020, 12:20 PM
https://www.autozone.com/electrical-and-lighting/toggle-switch/painless-wiring-20-amp-single-pole-on-off-on-toggle-switch/196358_0_0

If I use this exact toggle switch can I forget about using the fuse and female connector you suggested?
Also it's a 20 Amp is this okay?
Should I use a 30 amp switch?
Title: Re: Replaced in tank fuel pump and still not working
Post by: My.winnebago.tribe on October 10, 2020, 05:52 PM
I've got it running!
I will submit video link soon
Title: Re: Replaced in tank fuel pump and still not working
Post by: tmsnyder on October 10, 2020, 07:31 PM
Sorry for the slow reply but glad you got it running.  Can you draw out what you ended up doing?
Title: Re: Replaced in tank fuel pump and still not working
Post by: Oz on October 10, 2020, 10:23 PM
Excellent!   :)clap
Title: Re: Replaced in tank fuel pump and still not working
Post by: Ericb760 on October 18, 2020, 07:21 PM
Quote from: My.winnebago.tribe on October 07, 2020, 11:38 AM
I have a board over the hole I cut in the floor to gain access to the fuel pump...

Can you explain how you did this? I am about to pull my fuel tank to replace the sending unit and it would so much easier to do it from the top rather than dropping the tank. Thanks.
Title: Re: Replaced in tank fuel pump and still not working
Post by: Oz on October 18, 2020, 08:08 PM
How is it done?  Drop the tank first, guesstimate the location inside.  Check inside the approximate area and see what's there to ensure you might not be cutting into something critical, obstructed, or dangerous.

Once you know you can safely cut without causing more damage than good,  drill a hole up through the center point of the fuel pump location from underneath. You can mark the underside what your access panel limits are.  Push a thin rod, wire, or whatever, up through the floor. 
Go inside and find the hole you drilled and check the limit measurements you made underneath.  Then you can cut your hole.

The obvious question:

"Isn't there a way I can just do it from above without dropping the tank?"

No.  Well, yes. If you want to cut blindly through the floor and possibly cut wires and fuel lines and hit the gas tank, creating sparks... and still most likely be way off where it needs to be.

So yeah, the first answer makes more sense. No.
Title: Re: Replaced in tank fuel pump and still not working
Post by: Ericb760 on October 18, 2020, 08:18 PM
Yeah, I have no intention of cutting blindly through the floor. I was thinking more about the future and ever having to replace something on top of the tank again. Seems like it would have been a simple thing for Winnebago to add considering that fuel sending units/pumps all fail eventually.
Title: Re: Replaced in tank fuel pump and still not working
Post by: Oz on October 19, 2020, 07:56 PM
Yep, it would have made sense that they should have.  Just like it would have made even more sense to make an access door above the brake master cylinder, which usually requires even more frequent access.  But they didn't.  I wonder if the design engineers laughed about that...

;)  D:oH!  N:(
Title: Re: Replaced in tank fuel pump and still not working
Post by: Haven on November 25, 2020, 07:19 PM
Hey so we've got the same problem I think... I pulled the plug from the relay, but can't seem to work enough of the harness out to work on it.

Did you end up going with the simple switched bypass? Pics or video?