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Fuel lines schematic?

Crankme69

Crankme69

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Hello all,

Think I may have discovered why my truck is not starting the way it used too. I have a small leak wet lines between the tank & lift pump :mad2:

It looks like 3 lines between the tank & lift pump. I got 2 of em figured out what the hell is the 3rd one? Are there 2 return lines on these? I searched for a fuel line schematic has anyone got one they could post?

Maybe the 3rd line I spotted is something else like maybe a brake line?

TIA
 
Yep probably a brake line. Usually a 1/4 inch.

The return line is 5/16.

And the main fuel feed line is 3/8.

2 Orings at the sender, 2 at LP and 1 at the LP in the return line union.

This is the way my '93 is, anyway.
 
X2. BTW speaking of the return line union. i removed that and plumbed in there for my WVO conversion.
 
Come on guys help me out here, what is normally the issue? The return union, where is it located? Sending unit or?

Off course the friggin tank is 3/4 full, so I guess that I am gonna hook up my battery tender & use the LP to pump out the tank. The feed line to the LP looks new at least I do remember the previous owner telling me he had dropped the tank right before I purchased the truck to replace the sending unit. Are the replacement sending units like all the other replacement parts I have experience with, I mean pure chit?

Any & all suggestions comments recommendations or even a smart allelic reply would be welcome... lol
 
I believe the above posts were saying that the return line union was near the LP and a possible source for leaks
 
Just kidding, you asked for a smart ass.
Do you have a picture of the wetness?
The union is just forward of the lp about 2 feet or so.
 
lol

No worries!

I have been searching believe me :hihi:

I am not looking forward to dropping the tank :nonod:

Thanks, I'll try to snap a couple pics tomorrow. The tank lines are wet about even with the fuel inlet tank fill nozzle under neath about a foot to the rear of the LP. Now I discovered this after my 50 mile run home on the expressway. So it could be a little deceiving from that trip...the lines at the LP & on the engine side looked dry. There was also some drip marks on the black top where I park it, like it's been dripping some... so not sure what that is telling me yet...other then the fact that it's marking it's territory kinda like a friggin cat.
 
Crankme69 said:
No worries!

I have been searching believe me :hihi:

I am not looking forward to dropping the tank :nonod:

Thanks, I'll try to snap a couple pics tomorrow. The tank lines are wet about even with the fuel inlet tank fill nozzle under neath about a foot to the rear of the LP. Now I discovered this after my 50 mile run home on the expressway. So it could be a little deceiving from that trip...the lines & LP look dry
Click to expand...

Dont wanna drop the tank, pull the bed. I would. Lol, Usually easier in my experience if the tank is full. 6 or 8 bolts filler neck disconnect the harness and slide it back on the frame till you can access the tank.
 
The fuel lines between the tank and the frame are in perfect spot to collect dirt that stays put,the top of the sending unit is subjected to the same build up,more so if one travels gravel roads,add moisture to that when it rains or with road salt wet snow and it becomes a corrosive mix
Thin walled steel lines have the nasty habit of lose the battle over time. ;)
The rubber hoses at the FS unit often dry out and develop a crack or pinhole as well.:agreed:
and the tank itself could rust trough in that location too.
 
Thanks Bison!

I'm gonna head out there tomorrow & search around a bit. Might try to run the LP see if that tells me anything. May also try to take my leak down cylinder ring tester & apply a about 1 pound of pressure to the return lines or tank to see if I can pinpoint the leak. Hoping that I can see what is leaking so I can determine what I need to tear into...
 
Fun times are ahead for you I'm afraid.

Removing the bed is usually a MUST because the f'n clip nuts that clip into the x-members will break and spin. The tank strap bolts are only like a foot long too.

Then the tank straps are a real SOB to contend with. It's easiest to drop the straps and use two floor jacks then remove the tank out from the passenger side.

Then you have to figure out what you need to do for LINES.
 
Repairs complete

Some research today determined that it was indeed the return line leaking in the area of the frame rail right before it turns up towards the tank. After it turns up toward the tank it transitions from metal to rubber.

I cut that rubber hose (took a nice diesel bath) close as I could at the transition & installed a brass union barb that allowed me to replace all the corroded metal frame rail line with new rubber fuel line.

No dropping of the tank was required & no leaks.

My feed line to the LP will be next to get done...it has no leaks currently but does have some corrosion starting.

Thanks for all the info & replies...
 
Crankme69 said:
Some research today determined that it was indeed the return line leaking .....
Click to expand...

Are you sure it wasn't on the fuel feed side?

The return line just picks up what the injectors let go. All that fuel does is splash back into the tank.

The most critical fuel line section would have to be the piece from the tank sender to the inlet of the IP. It sees vacuum.

Hope you got 'er fixed though..
 
3500GMC said:
Are you sure it wasn't on the fuel feed side?

The return line just picks up what the injectors let go. All that fuel does is splash back into the tank.

The most critical fuel line section would have to be the piece from the tank sender to the inlet of the IP. It sees vacuum.

Hope you got 'er fixed though..
Click to expand...

bison he is (imo) discribing normal operating conditions with engine running. Except the vac/suction should stop at the discharge of the LP and become pressurized until IP.
 
?

Unless I'm mistaken hence the reason for the subject line on the post...2 lines come out of the tank 1 feeds the LP the other is a bleed return, right? The return line was wet & weeping and had left some of under carriage in that area wet as well as the frame rail was wet with diesel.

I was gonna take some pics but after I cut the return line & it pissed all over my sleeve I sad screw the camera & just made the repair... That sweat shirt went in the garbage.

One more thing, this truck has never made any noise when I unscrew the fuel cap? My Tahoe does & I swapped the fuel caps & the Tahoe still hiss's at me but nutta nothing when I pull the cap off the truck??? Have no idea what that means just throwing out there for someone that might know...???
 
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