1989 P30 fuel line configuration at tank?

Started by ClydesdaleKevin, December 01, 2013, 08:26 AM

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ClydesdaleKevin

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 and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.

circleD

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.

ClydesdaleKevin

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.



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

Kev and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.

pvoth1111

My sender only has two lines coming out of it....that photo may not be your exact unit.....
We call our coach "Charlie Brown"

ClydesdaleKevin

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
Kev and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.

bluebird

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.

Froggy1936

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
"The Journey is the REWARD !"
Member of 15 years. We will always remember you, Frank.

bluebird

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.

ClydesdaleKevin

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
Kev and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.

ClydesdaleKevin

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?
Kev and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.

bluebird

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.

ClydesdaleKevin

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
Kev and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.

bluebird

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.

cncsparky

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 ???
-Tom

ClydesdaleKevin

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
Kev and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.

Rickf1985

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

Elandan2

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
Rick and Tracy Ellerbeck

Rickf1985

And also to prevent vapor lock on the long travel from back to front.

M & J

What about a vapor purge line back to the tank from a charcoal canister? My 87 P30 has one.
M & J

ClydesdaleKevin

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

Kev and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.

ClydesdaleKevin

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
Kev and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.

ClydesdaleKevin


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
Kev and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.

legomybago

You gotta love the "mystery" switches....it's always a treat when you figure out what they do
Never get crap happy with a slap happy pappy

circleD

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.

ClydesdaleKevin

Mine is carbureted with an Edlebrock 1411. 

Kev
Kev and Patti, the furry kids, our 1981 Ford F-100 Custom tow vehicle, and our 1995 Itasca Suncruiser Diesel Pusher.