Solving my fuel lines craziness. (pic included)
 

Hey all,

I believe this fuel filter and lines are creating issues and resulting in leaking fuel. I believe there is pressure building because the fuel is leaking out of the area where you plug in and fuel up.

Can you all help me figure out what in the world is going on? I just bought the truck and don't know what the fuel line set up is supposed to be but this looks wrong.

Best
Bradley


https://cimg2.ibsrv.net/gimg/www.for...accabf2f17.jpg

Just............WOW. Someone really worked hard at messing that all up.

That fuel tank sending unit should NOT be under the truck by the tank switch.

Those four empty ports on the tank switch should have lines attached to them that run to each tank. Two pressurized, two return. The two on the front(right side of picture) go to the engine.



https://cimg1.ibsrv.net/gimg/www.for...90141afdb9.png

My guess is your TWO 90* lines go to the bottom fittings, the TWO straight lines go to the top fittings.

Hey freight train,

Thank you for your help man! It’s crazy huh? Do you think I ahouod get a new fuel sending unit? Also where should it be instead of under by the tank switch?

bradley

Holy Hell!!:-missingt

What was this guy thinking?

That silver thing with the rigid lines.. that is the top half a fuel delivery module normally found inside the gas tank!

So what year is this truck? And how many tanks does it have?

Oh geez!

Haha well that would explain why the pressure is all crazy.

Bradley

For visual reference: This is where that sending unit goes.....

https://cimg7.ibsrv.net/gimg/www.for...a86b3715dc.png


Going by the tank switch, you have TWO tanks. Which one have you been using? I'm guessing one is missing?

It looks like it was converted to a single tank set up and the sending unit top is being used to tie the return lines together. Why would you tie the return lines together is another question if you only have one tank in the system. The return from the engine must connect on the back of the sending unit plate. If there is only one tank you couldn't overfill the tank with the return fuel. More info is needed on the truck. That is craziness, for sure.

Go to an auto parts place and get some fuel line and inline barbed connectors. Throw away the dual function reservior and the extra sending unit, then cut and extend the original fuel lines over to the front tank.

My dual selector went bad, like so many have, and started sending fuel to the rear tank. The rear tank had not been used since before I bought the truck used in '91. I believe it was about 5 years ago mine went out, and it turned out my rear tank was rusted out on top. So now I had a rear tank full of nasty, stinky, rotten fuel that would pour out when driving or when parking on a hill.

Since I don't need the rear tank I removed the rear tank, the tank selector, bought the new fuel line and barbed connectors that matched the factory fuel lines, and in a short time had the front tank hooked up and looking like it came from the factory that way. All it took was cutting, splicing, and routing the new lines, which are only about a foot or less long if I remember correctly.

The old connectors are still used at the tank. Just cut off the two lines that went into the front of the selector and splice there.

Hey everyone,

Thanks so much for your input here!

So, the truck does have dual tanks, but like you guys are saying it's seems like it's converted to do a single tank. It's a 1989.

I've got it at a shop right now, but those guys kinda need some direction on what to do or what it should look like (i.e. where the lines ought to go - what stuff should stay / be replaced) There's just so much going on down there they're kinda confused as to what is necessarily the best way forward.

Does anyone have a diagram or guide on what lines go where and where the pumps, reservoirs and all that is supposed to be?

Bradley

I don't know how much this will help, but attached is the section from the service manual for the fuel tanks, lines, tubes, pumps, etc. It is from a '96 service manual though. The 1996 f-series does not use the dual function reservoir shown in freight trains post. You're '89 is the last year to use them. From '90-'96, the pumps, sending units, etc were all in one unit called the Fuel Deliver Module, and they were located inside each tank, as the attached shows:

Also, FYI - here is a great link that might help as well:
https://www.supermotors.net/registry/2742/12737-2

http://www.supermotors.net/getfile/6...all.jpg%20alt=

This would be what you need.

These are not the best pictures, but this is what I did with mine. I cut the fuel line connectors off for the front tank where they entered the dual function reservior at the rear of it. I then spliced into the fuel line going to the frame mounted fuel pump and the return line from the engine after I cut the push on connectors off of those two.

From there it's just a matter of measuring and pushing the barbed fuel line connectors into the new and old fuel lines.

It's dirty under there, but the line with writing is the new I got at Autozone, along with the barbed connectors. You can see the mounting spot where the dual function reservior went in one picture.

I would almost guarantee your selector is bad, and needs to be done away with. That's why your fuel lines are messed up like they are.


https://cimg5.ibsrv.net/gimg/www.for...9ade5fea4e.jpg

https://cimg6.ibsrv.net/gimg/www.for...5f4cd4f6da.jpg

I almost had a seizure looking at that first pic!

The supply and return lines are different sizes, returns smaller diameter than supply, so they should be able to keep those straight. That system worked with the low pressure pump in each tank filling the reservoir in the DFR, depending on which tank was selected by the dash switch. The high pressure pump took fuel from the reservoir to feed the fuel rail on the engine. If you bypass the DFR and tie one tank's lines into the lines on the other side of the DFR, eliminating the reservoir, I don't know if high pressure pump will pull from the tank, or how the system would work with low pressure and high pressure pumps in the same line. That doesn't sound like it would be a good thing. You could disassemble the DFR and free up the sticking valves.