Hey guys. Since I might be replacing all of my fuel lines at my sister's house, anyone know offhand how the fuel lines are supposed to attach at the tank for an 89 P30 with the in-tank electric pump?
Its possible that I might have switched a line when I replaced the pump, so is there any diagram to show me which line is which for when I do the rubber hose replacements?
My tank has 4 lines coming out of the top of the sender/pump cap. Spread out side by side like fingers.
Obviously the 1/2 line is the main fuel delivery line. I thought I was careful with keeping track of the others, but now I'm not so sure. The other 3 lines are 3/8 or so. Ever since I replaced the pump, the sender makes my fuel gauge go a little wonky, especially when I'm below 3/4 of a tank and step on the gas. My fuel gauge acts like there is a whirlpool of fuel and won't stay constant until I take my foot off the gas. I think its possible I switched a line around so that the return line is now going to the wrong place and is causing this, and might also contribute to the fuel delivery problem I was having with the genny, which tees off of the return line.
So is there a diagram for this, or do I have to pull the pump cap off again and try to figure out where the return line is supposed to come in? I think I could figure out quickly enough which line was a vent, since it wouldn't go down into the fuel, but the return line on ours has to go down into the fuel since it also feeds the generator...and I have NO freaking clue what the 4th line could possibly be for!
All 4 rubber lines go over the tank and then meet steel lines above the rear axle. Again, I know which line is the main delivery, and found out by accident which line is the return line. I'm assuming the vent line goes to the front to a charcoal canister. What does the 4th line do, or is it an additional vent, or even an additional return line?
A diagram would make this so much easier than trying to trace the steel lines all the way from the back near the fuel tank and all the way to the front where they meet the mechanical fuel pump and whatever else they go to.
Anyone?
Thanks!
Kev
Kev, my experience with fire trucks and the little bit of RVs here lately is that an electric pump needs a vent because it pulls harder than an exterior mechanical pump. I'm still betting that you have the main, a return, a vent, and one that is suppose to go to the generator and they are "usually" in order or side by side like that. If you still have part # from last time you can call advance auto and they can pull it up. I'm sure there's a manual for that but WOW the amount of books. Good luck man.
I just viewed a picture of the whole Dorman sending unit on the Dorman website, and it looks like there may be 2 return lines. The 1/2 line goes from the electric fuel pump itself then to the steel line and to the front to the mechanical fuel pump.
The one next to it appears to go to a pickup line above the sending unit float and pump, and the next one over appears to go to a pickup line a little longer that exits below the pump, which if I mixed those 2 up could account for return fuel splashing down on the float and making the gauge erratic under load. The next line over doesn't appear to go to any pickup so must be the vent.
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Assuming that this is more or less identical to my sending unit, which from my memory is the case...its been a while since I pulled the pump!
So, would there really be 2 return lines, and why?
If there are 2 pickup tubes...the 1/2 line is fed directly from the electric pump...then it stands to reason that there are 2 return lines. I'm just not sure. I do remember not being too sure of those 2 middle lines when I put them back on.
Anyone have any idea which one of those 2 middle lines should feed the genny? Now that I think about it, wouldn't it be better to feed the genny off the shorter pickup and not the one that feeds from the same level at the bottom of the pump so we don't run out of gas for the RV if we are using the genny?
Now I'm even more confused...lol!
Kev
My sender only has two lines coming out of it....that photo may not be your exact unit.....
The picture is just like ours, with 4 lines coming out of it. I'm pretty sure its exact down below as well. The only difference is the external fittings, which on ours are all the push-on kind with hose clamps.
Kev
Kevin your generator line shouldn't be off the return line, as the pump could suck air. It should come directly from the tank. You may have to pull the unit again to mark which line goes where. That maybe a universal sump, used for both electric or manual pumps. If that's the case the other line going to the bottom has to be the return line. The tank vent/canister should be the shortest tube in the tank. The generator pick up should be near the middle or a little lower. Only problem I see with this returning the fuel to the bottom will keep the sediments stirred up.
Hi Kev . It looks to me like The large outlet should go to a hose that goes up to the filler neck just under the filler cap. Next one to the right in the picture is for the generator. Next to the right is engine main feed line . And last one is fuel return line (if so equipped) or a vent line to a canister Without seeing veh its hard to tell . There should have been a sticker with hose layout on the veh somewhere But it may have been on original air filter housing wich is ?? Frank
Froggy the line you think is for the generator is for the electric fuel pump. I don't think this setup is for a MH with a generator fuel line. I'll look in my MH chassis manual and see if they show the module.
Yep, the big line is definitely for the fuel pump.
Now I know for certain that the one on the far right is the vent, as it doesn't go down into the tank.
What still has me puzzled is the possibility of 2 return lines! The two in the middle, both short and long, have rubber hoses that go to metal lines that run to the front of the rig, and not the generator. Off of one of those lines is a T fitting that goes off to the generator.
It makes sense to put the return line that Tees off to the genny on the shorter pickup tube. But that means there is a second return line, because a vent line going to a charcoal canister wouldn't be submerged in the gasoline.
Which makes me wonder again why 2 return lines, if the other line really IS a return line? Maybe it goes up front and is capped off for some unused application?
Or maybe the mystery line goes directly to the mechanical fuel pump to feed it, while the 1/2 inch line also feeds it from the electric in tank pump?
There do seem to be a lot of lines going to the mechanical pump, but I haven't taken a close look at it in a while so I can't remember exactly, and now its dark and I'm exhausted from packing all day. I have a brand new mechanical pump sitting in my RV tote, so I can look at that in the morning before I put it in the Jeep.
So maybe that is the mystery? There are either 2 feed lines going to the mechanical fuel pump, or there are 2 return lines going to the tank.
So if one of those middle lines is a feed line to the mechanical fuel pump, then obviously that should be the one that goes deeper into the tank, right?
Maybe 2 feed lines is a failsafe in case the electric pump goes out and would allow you to limp to a repair shop?
It makes more sense to me that there would be 2 feed lines rather than 2 return lines.
So if the return line is supposed to go to the shorter pickup tube, then it would make sense to tee the genny off that line, right? So it can't suck all your gas away?
But if a return line can suck air, why did they T it off the return line?
It makes a little bit of sense to me why they would omit an inline filter though on the genny if it tees off the return line, since the fuel is already filtered on its way back to the fuel tank...although I did add an inline filter just a day ago when I replaced the electric fuel pump and some of the fuel line and the cracked T fitting.
So there are some things I know for sure...the line that the genny was teed into is definitely a return line, because when I pulled the t fitting and attached the genny's metal line right to the rubber hose going to the tank...to see if it would pull fuel right from the tank, and it did...when I started the RV engine, fuel started pouring from the disconnected line.
And I know for sure that the big 1/2 line is a feed line from the electric in tank pump.
And I know for sure that the line on the far right is a vent, either to air or a canister, I don't know or care.
Its the 4th line that is the mystery! Its either a secondary feed to the mechanical fuel pump, or its a secondary return, or it goes nowhere and is capped off...but I seem to remember seeing 3 rubber hoses attached to the mechanical fuel pump, one big one and 2 smaller ones.
I guess I could pull the mystery line and have Patti turn over the engine and see if fuel spurts out or it has some suction.
But it would be easier if someone knew the answer right off the bat.
So I guess the question now is this...does the mechanical fuel pump have 2 inlets and one return line, or one inlet and 2 return lines?
Kev
So curiosity got the better of me as tired as I am, and I just crawled under the rig with a flashlight to look at the mechanical fuel pump.
It only has 3 lines going to it. One is a big half inch line...the feed, the other is a metal line going to the carburetor, and the 3rd is a smaller rubber hose that must be the return line!
And that is it! So its still a bloody mystery! what in the world is that 4th line?
And where does it go, and why is it submerged in the fuel in any event?
Anyone have any clue?
Kev
What the heck is that 4th line for?
Kevin, I was just looking at my manual. Clear as mud. Then I started searching the net for RV sending units. Can't find any thing that has a separate line for the generator. If all 4 lines are hooked up I'd trace them down. Your right on the vent line, as it looks to have a check valve in the tank. The return line has to go to the bottom of the tank according to the pics I'm seeing. The bad is the generator can run you out of gas. Is this the original sending unit in your rig? I haven't had my tank down on this coach, but I did on my Itasca and it had a separate line for the generator. That real big line that barely goes in the tank has to be a vent and probably attaches to the fuel filler neck to relive the pressure when pumping fuel in. Fuel line, return line, vapor canister line the smallest one, that makes 4.
The really big line attaches to the electric fuel pump, which I replaced last year so I'm sure of it. Its short because it attaches to the electric pump with a short length of rubber hose and 2 hose clamps. So the big line is definitely the fuel feed to the carburetor.
1. The line on the far left is definitely the vent, since it doesn't go into the fuel.
2. The line that actually does tee off to the genny is definitely a return line based on the fuel pouring out if it under pressure when the RV engine is started.
3. There is a dedicated very big hose, probably 2 inches, that feeds into the top of the fuel tank and goes to the filler door.
So that still leaves the 4th line as a mystery!
There are only 3 lines going to the mechanical fuel pump. One goes to the carburetor. One goes to the half inch supply line from the electric fuel pump, and the other must be the return line.
That still leaves the other line as a complete freakin' mystery!
It can't be a secondary vent line since its submerged in the fuel.
So what the bloody heck is it, where does it go, and what's it for?
I'm tempted to reconfigure the whole darn thing if its not a return line...eliminate the tee fitting, have the return line go to the deep pickup tube, and route the genny line directly to the shorter pickup tube. Then whatever that 4th metal line is can just stay a mystery for all I care, as long as fuel doesn't pour out of it like the known return line!
Anyone have any idea what that 4th line is so I don't have to try to trace it along the frame rail, which isn't easy the way our coach is laid out with basement storage and lots of stuff in the way along the frame?
Kev
Kevin you sure you don't have 2 lines going to the fuel door? My old Itasca had the fuel fill hose very large but it went directly to the tank. Then about a 5/8 hose that went to the tank also, I just don't remember where it attached. I'm too lazy to go crawl under and look at mine.
Kev, do you think the generator connection to the fuel pump return is a factory setup? That just doesn't sound right to me i?? . Here is my rendition of how it should be (without looking at your coach personally).
1. Obvious large connection for fuel supply to pump.
2. Return from pump to the line that goes to the bottom of tank. (3rd from left)
3. Vent line from charcoal canister.
4. Gen connection to half-way down tube.
Hm? IDK ???
I'm assuming its a factory setup, since the rubber hoses near the tank were coated with spray foam insulation like everything else under the rig.
I guess the only thing to do is pull the mystery line and have the wifey turn the key and see if gas sprays out.
If it doesn't, then I'm going to pull the pump again to make sure which line is which for certain, then reconfigure the hoses and eliminate the tee fitting, bring the return to the bottom of the tank, and hooking the genny up to the tube that doesn't go all the way down. I might even extend that tube if it isn't long enough with a piece of rubber hose, some clamps, and maybe a short length of metal tubing.
I wish I had taken pictures when I replaced the fuel pump last year! It sure would have made my life easier now...lol!
Kev
I will make a suggestion here as far as the extra line. Is it possible that this tank was also used in diesel configurations? All of the same lines to the engine would be used but if it had a diesel generator then it would require a return from the generator as well. I just found out that I have a serious fuel line leak by the tank while running so I am going to have to get under there to find it. Any suggestions as to access? I see a photo of an access hatch, what MH is that in and where? I have an 80 gallon tank and no way am I pulling that in my driveway!!! Half full at that.
Rick
Hey Kev, I'm thinking that maybe that return line comes from before the mechanical pump. That way, even in a full throttle situation, where all the fuel the mechanical pump can deliver is being used by the engine, there is still a return to keep the flow going and keep the electric pump cool. Just a thought. Rick
And also to prevent vapor lock on the long travel from back to front.
What about a vapor purge line back to the tank from a charcoal canister? My 87 P30 has one.
If its a vapor purge line, I'll just block it off or tee it into the other vent line...but why would it be submerged in the fuel? If its some crazy secondary return line I could tee it into the other return line and feed the genny off the shorter tube by itself.
Some previous owner might have jerry rigged the line now that I think of it though, since I can't imagine Onan or Holiday Rambler not having an inline fuel filter!
I'll think about it and let you all know what I end up doing. Once I get to my sister's house I'll more than likely pull the fuel pump and sender again to make sure of what line is what, then replace all the rear fuel lines...and pull that mystery line and have the wifey start the engine. That will certainly determine if its a return, and if not I'll see if my charcoal canister has one line or 2, and if its 2 I'll probably tee them together, then use the shorter tube as a dedicated genny feed line.
Kev
So I had a thought while driving the rig today, when I glimpsed at the switch I use for my electric cooling fans...its in a hole in the dash that didn't have a toggle when I bought it, but is labeled Auxiliary Heater.
A search on the net yielded very little, except there were a few old HR coaches that used the engine coolant to a heater under the rear bed, and a toggle on the dash board that controlled fan speed.
If that is the case, then its unrelated...but was it possible that there was an option available for an auxiliary gasoline powered heater like on old VWs?
That would explain the extra fuel line. I still don't have a clue...lol!
Kev
There are a bunch of toggle switches on the dash that I still have no idea what they are for, like one labelled ICC Courtesy. Another is labelled Accessory and does nothing that I can tell. Another goes to the non working horns on the roof, labelled Accessory Horn, and one says Radio Power, but doesn't go to the radio or CB.
The only place without a toggle when I got it was the Auxiliary Heat, so I was just wondering...lol!
I'll figure it out in my sis's driveway over the next few days before we head west and travel a great distance.
Kev
You gotta love the "mystery" switches....it's always a treat when you figure out what they do
My radio switch turns on my FM radio even when the key is out of the ignition ( hooked up or cut maybe? ) And I was wondering about that heater under the bed I thought it went to the thermostat but it's electric with a heater coil in it, plus my air horns kinda work with the button but I'll be upgrading to emergency studder tone ones soon :D . I'll be under my rig Friday for a couple of hours and I'll look again for an extra line but I've used that camera and everything. I know yours is EFI but HEY!! you never know and I have to look for a wire hanging down for HandyDan.
Mine is carbureted with an Edlebrock 1411.
Kev
Oops :( I figured it would've been EFI. I got my years mixed up. Do you have a washer and dryer on board that could have a gas power assistance? I'm out of ideas friend.
Mystery solved! And it wasn't even a mystery, just mistaken identity of what I thought was a fourth fuel line which was actually a brake line for the trailing axle...lol! That and a faulty memory, because I could have sworn that there was a 4th line coming out of my fuel tank...but when I crawled under there today, there are only 3!
I took the lockring off and removed the pump/sending unit assembly just enough to identify which hose when to where.
One is definitely a vent, one is the main 1/2 line coming directly out of the electric fuel pump, and one is the return. So it must be a factory setup for the genny to tee into the return line.
I'm not going to bother replacing the vent line. And the half inch rubber hose, which is really hard to get to, is a very short 10" run to the fuel pressure regulator (which I hope NEVER goes bad, since its on the opposite side of the tank and would require dropping the tank to replace...and from the regulator right to a steel 1/2 line which runs all the way to the front mechanical fuel pump.
I think the genny fuel delivery problem is the 10 whole feet of crusty rubber fuel hose that goes from the steel line where the genny tees into it, all the way back to the fuel tank.
So that is the only rubber hose I'm going to replace for now.
I traced everything back to the front, and lost the vent line somewhere...but the other two lines run right to the frame rail just a few inches from the mechanical fuel pump. They are short, and look okay, and since they are very hard to access on our rig, I'll leave those hoses alone too for now. Our coach has that extra steering stabilizer called a Safe-T-Plus, and it would have to be removed in order to access the pump from below, or I'd have to take the alternator out to access the pump from above. If it ain't broke, don't fix it!
Once I replace that 10 foot section of rubber hose, the genny should be good to go. So that is tomorrow's project.
By the way, I made another misidentification. What I thought was a big 2 inch hose from the filler neck is actually a vent that ties into the filler somehow via a canister next to the filler neck...which is a massive hose barely visible entering the side of the fuel tank.
I took pictures and will post them when I have a chance.
Kev
My experience with vent lines are to keep them like water pipe. Make sure it has a slight angle going up and out of harms way. Put a new vent cap on there and since its not a truck bed and you live in there aim it towards a place that fresh air moves freely even sitting still. I modified some trucks for water crossings and the vent lines need to be kept clean and clear.
Maybe I'm just showing my ignorance, but I can't picture why a generator would be teed into the return line. Maybe I just don't understand how the whole system works, but I would think getting gas to the generator would be extremely difficult if it was relying on return gas. Seems like it should come right from the tank. I did find this diagram of a Ford system that the owner modified in case the intank fuel pump was to fail. He made it so the engine could still run by bypassing the fuel pump. However, according to the forum dialogue that went with it, it wasn't working well.
Dan
I initially agreed about the genny being wrong tapped in the return line, unless the return is piped below the fuel level near the bottom of the tank. All genny fuel supplies are drawn from above the bottom of the tank to keep some fuel for the engine so the tank isnt run dry by the genny. If his return is a few inches above the bottom then it will draw fuel as it should regardless of the engine running.
my genny is teed I into return line...
Yep, the return line does go to a tube that is just a couple of inches shorter than the bottom of the electric fuel pump.
I'm hoping that by replacing that rubber line today it clears up the fuel delivery problem completely. It should, since I already replaced the genny's fuel pump.
Kev
Bingo!!! All fixed! I replaced the hose (it ended up being 5/16 not 3/8, so another trip to O'Reilly's was required...and since it was 10 whole feet they sold me of the 3/8 they let me exchange it and the hose clamps for the right ones).
I put it on, zip tied everything in place, and started the genny.
It took a bit to prime all the way from the tank, but then it evened out and I could see a steady fuel flow in the clear plastic fuel filter.
I let it run for a whole hour under load with the AC blasting, and the genny is running great now!
Problem solved and fuel line routing all figured out!
Kev
I know I'm late to the party but I'm having the same problem and cant find anything online about it.
Any idea what lines connect to the tank here? Thank you!
You can ask questions, but only use 1 thread for your question. Don't ask the same question in multiple threads. You need to pull the lines back out of the tank and mark them as to which one is the longest, it goes to the fuel pump. The return line from the front goes to the shortest one. The generator goes to the the next longest. The other one is the vent and should be the largest on of the bunch.
On my 1993 rig which is granted younger than being discussed the 3/4 length dip tube is the feed for the Onan generator which has its own electric fuel pump. It is discussed in the owners manual as being a feature to always have a reserve in the tank.
One line will be a vent line, one will be the main line (1/2 inch), and one will be the return line. On ours, we don't have a specific line running to the generator...it Tees into the return line.
Kev
I thought the vent line was the shortest in the tank. In 1985 they changed the configuration of the gas lines (in tank fuel pump). Therefore my 1983/4 tank doesn't look like the one pictured at all.
If you cannot tell by the lines telegraphing themselves to the correct position then the only way to be sure is to pull the unit out. Be sure the gasket is still good before putting it back or it will leak from sloshing. I would use Permatex #3 gasket sealer if using the old gasket.
I got this picture from a friend. May or may not be of any help, but thought I would post it.
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The 454 will go to the longest pickup tube
The genny will go to the next shortest.
The fuel return on the last one.
(In a nut shell) ???
Oh, I just re-read you post....If you already have the tank installed. I cant help....lol :-[
I strongly advise replacing the old lines while you are there but the fact that the old lines are hanging down there should be a big help. You will find that they have a set to them and they will pretty much point directly to the tube they belong on if you hold them up at the level they would be at when the tank is in place. Every fitting is a different angle and those hoses will be pointing in their respective directions once held in the proper plane. Just hold them lightly and back about 6 or more inches from the ends.
Okay I will try that. I'm also not 100% certain the sending unit is facing the exact same angle as when I took it out (it's very close. Is there any way I can test what line goes where if that doesn't work? This is the only thing holding me back from re-installing the tank.
The sending unit is almost always keyed with a tab so it will only fit one way.
this sending unit has 5 screws holding it in
Quote from: MattyT on December 03, 2015, 08:33 PM
Okay I will try that. I'm also not 100% certain the sending unit is facing the exact same angle as when I took it out (it's very close. Is there any way I can test what line goes where if that doesn't work? This is the only thing holding me back from re-installing the tank.
There is only one way to do this. Since you
do not have the tank installed, take the sending unit back out and take note of the pickup tube lengths. Reinstall. Then you need to figure out which rubber fuel line goes to what by tracing/tracking/following them...While your there, replace the rubber fuel lines like someone already mentioned.
Good Luck :)ThmbUp
I think my unit uses a similar setup. If so, the lines will be as follows
-the brass elbow fitting threaded to the top of the tank is the fuel return from the engine
-the 3rd barb on the sending unit, the one that is most separate from the other two and has a restrictor orifice jammed in the end is the fuel tank vent
-the largest of the three, and the one facing mostly toward the front of the vehicle should be the fuel feed to the engine
-the smaller one in the middle of the three should be the fuel feed to the generator
Depending on how much fuel is in the tank you could stick some hose on them and at least verify the engine and genny feed, as you should be able to suck fuel. the vent and the fuel return will NOT dip into fuel no matter how much gas is in the tank.
hope this confuses you... I MEAN HELPS
****edit**** since this thread was combined...
my post only applies to carbureted configurations with NO fuel pump in the tank.
You're correct I tested the fuel lines by placing them in a water bottle, I'm going to replace some of them considering theyre falling apart and it should be good to go
If the tank is down or can easily be taken down I strongly suggest replacing the lines with good quality ones. I also clean the tank and put new paint on it with new clamps on when I do this work. Rick knows his stuff and so do the others commenting on here. Its years of us messing up our selves. Good luck.
Good AM--Jan02 2016--Happy New Year--
My 89 Itasca has the two line configuration in fuel tank sender/pump unit.
Just wondering if anyone knows where the smaller 1/4 inch one comes from ? i?? Don't think it's generator feed ,as it goes to the bottom of the tank.Don't have generator, but compartment is wired & plumbed for it .
I've managed an access hole thru the floor to check for a clogged strainer/sock, just waiting for the new one to arrive before pulling the unit.
Thanks for any replies---Harv
Return line from mechanical fuel pump
Thanks,Dave---I thought it should be, but earlier on I had disconnected that line at pump and blew back thru it, just seemed to hear air coming into tank without bubbling?
Maybe the tank was too low, but I got 8 gallons out when I drained it. Anyway, I 'll check it the same way after disconnecting the sender , got about 20' of plastic IV line , works well for doing things solo.
Have a nice day---Harv
Like shown in this picture, the return line stops at the top of the tank just under the attachment cap
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Quote from: ClydesdaleKevin on December 08, 2013, 10:56 AMAnd the half inch rubber hose, which is really hard to get to, is a very short 10" run to the fuel pressure regulator (which I hope NEVER goes bad, since its on the opposite side of the tank and would require dropping the tank to replace...and from the regulator right to a steel 1/2 line which runs all the way to the front mechanical fuel pump.
edit: I just found this thread discussing the following question here:
http://www.classicwinnebagos.com/forum/index.php?topic=12390.0 (http://www.classicwinnebagos.com/forum/index.php?topic=12390.0)
Has anyone tried to replace this hose you mention? The guys at the auto parts shop don't know what to do with it. Mine is dry and cracked, and since the RV vapor locks, every single source of potential air introduction is being absolutely eliminated. I have a 60gal tank. The brake line is also being replaced while access is open while the tank is dropped.
HI PRESSURE HOSE
GM PART NO.:
15530451-40 GAL.
15530401-60 GAL.
If all else fails take it to a shop that makes hydraulic lines and they may be able to male you one. Even if you can find on with the right ends on it you can cut it and insert a longer piece of fuel injection line with double barb fittings and clamps. The in tank pump only puts out 10PSI max so you are not going to blow the line apart.