gldrsh

I narrowed down my air leak to the fuel tank module sending unit. Has anyone had this problem? I have not dropped the tank yet,maybe tomorow. I can see the top of the unit and booth the feed and return fittings are rusted. the only replacement unit available is the Carter p744699r. I was thinking if I could replace the supply line with a rubber hose from the sending unit to the fuel pump it might work. But could the leak be inside the tank from those little plastic hoses in the module? I don't want to spend almost $200 to fix an air leak. I don't understand that Vulcan straw and if it fits in the factory module. Anybodies experience with this that they had would be appreciated.

AlpineRAM

I did replace the little plastic line in my fuel module with a rubber hose, then cleaned and rust-proofed my outer lines that already had pinholes, used a shrink-tube to get them back to airtight again, and used 10mm id (3/8") fuel hose from the tank module to the lift pump.
Did the same on the 12V of a friend, works good for the last 5 years.

gldrsh

Thanks AlpineRam for the response. Do you mean the plastic tubes inside the module you replaced with rubber? And the two metal ends sticking out of the module you used electrical shrink wrap on? And from those two outlets used rubber hose all the way to the lift pump;about 6 feet or so? On the supply and return lines? Thanks for clarifying. When you lowered the tank did you use ratcheting straps to lower the tank? thanks.

AlpineRAM

One of the plastic tubes inside my module had a leak where a screw tip had caused a hole- the result was foamy diesel to the LP and IP. So I cut the plastic tube and slipped a piece of rubber hose over it. Fixed it there with zip ties. Filed off the offending tip of the screw.

The metal ports with the quick connect fittings were corroded, so I used a fuel proof rust inhibiting paint, a bit of electrical shrink wrap and then a 10mm ID hose to the lift pump and an 8mm ID hose for the fuel return. On the lump side I just cut the hard line and slipped the fuel hose over it for about 8" and secured it with 2 clamps. There's no pressure there, but you need to avoid air ingestion.
I don't know how long the hoses were, had them on reels in the shop. But 6-7feet per hose should be sufficient.

For lowering the tank (close to empty) I used a small wheeled hydraulic jack and a piece of plywood about the size of the tank.
Make sure and double check that you have everything disconnected before lowering the tank..

(Don't ask me how I know about the fuel sender wiring... )

gldrsh

Thanks for the response. I assume you cut the factory plastic hoses from the the metal lines that run behind the fuel tank and replaced them with rubber lines from there to the sending unit and used the original long metal lines behind the fuel tank? And inside the sending unit/module you slipped a piece of rubber hose to the plastic line and attached it with a plastic tie wrap? Thanks for the long piece of ply wood idea under the tank. Sounds easier then straps on each end to lower it. I appreciate your help very much.

AlpineRAM

I replaced the metal and the plastic part of the fuel lines that runs in the frame rail with rubber hose.
While the metal part looked good (shiny) I could easily break it in two with my hands, corrosion ate it from the inside out.
I have a 10mm ID Gates Automaster hose from the top of the tank to the small green part almost on top of the engine in the following picture



Inside the tank module one of the plastic pipes had a hole- I cut the pipe there and slipped a bit of fuel hose over one end of the cut pipe, then re-connected the pipe by sliding the hose over the cut part and fixing the hose to the pipe with zip-ties. (fuelproof zip-ties from an automotive shop)

gldrsh

Thank you very much for clarifying my questions. I will be doing this work next week. I will update on how it went,thanks.

gldrsh

I was going over all the notes so I understand what I will be doing. On the return line;I am reading that you used the existing metal line that runs along the frame and only replaced the that short quick plastic disconnect piece that connects to the sending unit with rubber and the supply side you ran the entire distance from the sending unit to the fuel pump with rubber hose? Thanks AlpineRAM for your help.

AlpineRAM

Well, I did replace both lines completely.
Both metal lines were corroded beyond salvage. Only the ends quite close to the engine were re-used, the rubber hose slipped over it for about 3-4 inches and hose clamps to hold the hoses on.
The fuel line is 10mm inner diameter, and the return hose 8mm if I recall it correctly.

On the fuel tank I cleaned and painted the short metal tubes that usually connect to the quick connects, "coated" them with a bit of fuel proof shrink tube and slipped the rubber hose over them as far as they would go, again using hose clamps.
I used zip-ties to hold the rubber hoses in place, taking care that they would never pull on the fittings.

HTH

gldrsh

AlpineRAM I need your help again. I think you are the only one who has lowered the fuel tank on this website. I just lowered the tank and thought I could disconnect the fuel lines once I got a little more room. I didn't think I could get that plastic disconnect tool in there with the tank up against the metal floor. Any way I cracked the fuel fittings of the sending unit. They were very rusty and don't know if they could have been salvaged any way. Now I don't know how to unplug the electrical plug from the sending unit. I am about to break that so I quit for tonight. The tank is currently suspended by my floor jack under the truck in my drive way. As far as the sending unit;I do not want to spend $200 for a new one,finding one in a junk yard is impossible,so I am thinking of getting that draw tube they sell at Jenos Garage for about $60. What are your thoughts? Especially the electrical plug,thanks AlpineRAM

gldrsh

AlpineRAM;you must not have been on this website recently. Any way I just ordered a new sending unit;Carter P74699R. I don't think the old one was salvageable. The fuel outlets were very rusty and cracked right off when I was lowering the tank before disconnecting them. I removed the electrical connector but it didn't have that red tab that was supposed to be slid out. I may have broke it when I removed it. Hopefully it will still work. I will try to reinstall the tank in the next few days.I am working outside and rain is in the forecast for maybe two days.

AlpineRAM

Sorry, I was a bit busy..

The red tab is only a second safety so you can not press the unlock tab of the connector with the red part in. It should work without the red part.
But take a good look at the connector. (corrosion)

While you have the tank out replace the 2 fuel hoses.

Please do also check the brake line that is hidden by the fuel tank, they tend to corrode there and the consequence of not being able to stop is somewhat worse than not being able to accelerate.

gldrsh

Thanks for responding,by connector do you mean the two metal outlets from the sending unit? I bought a new sending unit so I was going to reuse the factory lines with the plastic disconnects. Do you suggest I use new rubber lines in place of the factory set up with the new sending unit? Thanks for helping me. Also the electrical plug;the red tab was missing like some one before me had it apart. I broke off some plastic tabs but I got it apart and it looks like it may still work. I might have to put some plastic tie wraps on it to secure it. Also I have not tried to remove the plastic ring that holds the sending unit in place. I have a very big pair of channel lock pliers. I don't know if they will open wide enough. Any suggestions on removing it? Thanks.

texasprd

You would have to have a really big pair of channellocks to remove that plastic ring. I believe I used a chain wrench to remove mine when I replaced the fuel gauge sender.

AlpineRAM

I would replace the stock fuel lines with new rubber hoses. Slip hose over the outlet of your new module. Secure with hose clamps.
I usually tap the white ring with a plastic hammer to shake it loose, and then I use a ratchet strap like a chain wrench.