Engine/Transmission (1994 - 1998) fuel line overhaul

[TSPowell]

The old beast has 271,000 miles with the stock fuel lines. Right now she wont start, because of the leaking fuel lines that everyone has problems with. I figured if Im going to do it,might as well do it right. So I want your input.



Im currently redoing to set up on my 04. 5 with the kit from GDP. Seems really nice, and there is a Push-lok dealer where I live, so I have access to all the different fittings and hose they make. Im going to do a custom job on the 95 with Push-lok.



Im thinking about running rubber through out the whole system. I know everyone says "make sure you get diesel rated line. " I don't know if the line from push-lok is but GDP is selling it and he puts together good stuff.



1. Run rubber line from the tank to the lift pump. Im thinking of bypassing the whole heater/filter portion and go straight to the lift pump. Heater causes problems (leaks) and Ill use an inline filter from Fleetguard.



2. Probably use the stock line from the lift pump to the filter. I haven't really thought about this portion yet. Just changed my mind; Ill come up with something.



3. Use rubber hose from the filter outlet to the injection pump. Push-lok makes banjo fittings.



4. Lastly, from the overflow valve straight to the tank.



I would really like to take advantage of a Walbro pump and go from the tank to the canister filter and completely remove the lift pump. Better yet, If I could figure out what to do with the injector manifold drain line, I would run line from the tank, to a Walbro, through filters mounted on the frame then straight to the injection pump. I belive GDP is working on that right now but I dont have time.



Any input, suggestions would be great. I will be starting on this project soon!

 

[Missouri Mule]

Marine grade hose (diesel rated).

 

[Joe G.]

I think you should keep the stock lift pump. It will increase flow as RPM increases. An electrical pump won't do that. It's way more reliable than an electric pump. You should use the stock steel lines from the lift pump to the filter and from the filter to the injection pump. There is pressure in those lines. Pressure spikes can get pretty high. Diesel rated hose for all the rest of the fuel supply system is a good idea.

 

[TSPowell]

No much of a response here... ... has anyone tried this????? Main questions are about lines from the tank straight to the lift pump (bypassing the heater/prefilter), and from the overflow valve to the tank. ??????

 

[Joe G.]

The filter is AFTER the lift pump. The fuel is sucked through the fuel heater (POS) and pre-filter by the lift pump. It is then pushed throught the filter and on to the injection pump. The unused fuel goes out the overflow valve and returns to the tank.

 

[TSPowell]

The filter is AFTER the lift pump.

I know its after the lift pump, I want to know if anyone has ran a line from the tank straight to the lift pump, bypassing the heater/prefilter.

 

[Joe G.]

The reason for the pre-filter is to protect the lift pump.

 

[TSPowell]

1. Run rubber line from the tank to the lift pump. Im thinking of bypassing the whole heater/filter portion and go straight to the lift pump. Heater causes problems (leaks) and Ill use an inline filter from Fleetguard.

Thats why I was going to use a small inline filter from Fleetguard

 

[R_Painter]

On my 04. 5 I installed a walbro pump and ran new 3/8 line from the tank up to the filter housing. I installed a small fleetguard inline filter before the pump and installed a big line kit from the filter to the cp3 bypass installed just before the filter housing I carry 42 psi fuel pressure at idle no leaks at all the glacier hose is rates for 300psi hope this helps

 

[TSPowell]

You used the same Fleetguard inline filter that im talking about. That way I can bypass the heater/prefilter assembly!

 

[Rams-n-Hogs]

If it were me, I would just replace the hoses in the fuel system that needed replacing. You'll probably be good for another 271,000 miles.

 

[Joe G.]

I'm thinking that doing anything else but replaceing the existing fuel hoses with good ones like from LarryB is way overkill.

 

[TSPowell]

I'm thinking that doing anything else but replaceing the existing fuel hoses with good ones like from LarryB is way overkill.

If you think modifying some fuel line is overkill, I don't want to know how you feel about bombing these trucks!! Whats your opinion on twins or dual CP3's or anything else thats overkill or just plain fun. Im trying to fix a problem that is OBVIOUSLY a major problem with the 12V's.

 

[Joe G.]

The stock fuel system on the 12 valve is NOT a major problem. Easy to fix. Very reliable. No electrical lift pump that's a major problem. There is a certain amount of paranoia about lift pumps since the VP44 fuel system lift pumps are so unreliable. All of the problems I've had with it have been easy to fix. The fuel heater was the only thing that was a puzzle. All of the stuff is original on my fuel system except the fuel hoses and the overflow valve. 240K miles on the old overflow valve. The fuel heater is in the garbage where it belongs. 244K miles on the truck. The fuel system is sure OBVIOUSLY a major problem. I would rather spend my money on injectors and other mods than on changing a good relilable fuel supply system.

 

[KennyM]

I ran all new rubber from the tank to the Lift pump and all new return line also. I kept the pre heater, but removed it and the lift pump to PM them. (To me it was easier to do with them off the truck) I also dropped my fuel tank and installed a rebuilt tank module. I ran all the new rubber fuel line inside plastic tubing to help protect it.

 

[TSPowell]

The stock fuel system on the 12 valve is NOT a major problem.

OK, when I meant major problem I was talking about the air leaks that appear EVERYWHERE in the 12V system, not the lift pump. If you look around at the 12V threads, the amount regarding air leaks in the fuel system probably outweigh any other. I would say thats a major problem.



Take for example the fuel return line: Overflow valve - steel line - rubber line - steel line - tank.

Why not go: OV - rubber line - tank.



I THINK THAT MAKE SINCE and isn't overkill. You remove a couple of rubber-to-steel connections, thus preventing a higher % of possible leaky areas.



EVEN BETTER:

tank - steel line - prefilter(leaks) - heater(leaks) - rubber line(leaks) - liftpump

OR: tank - rubber line - lift pump.



The stock system really seems overkill when you look at it from this point, doesn't it.



Joe G. If you want to keep criticizing my attempt to correct a problem, then do so. But thats not why Im here, I would like peoples input who have attempted the same fix.

 

[Joe G.]

I think that hoses from the overflow valve to the tank. And from the tank to the fuel heater/pre-filter assembly make sense. Especially if you live where roads are salted. If I get problems from rusty lines that is what I plan to do. Replacing the rest of the fuel supply system or adding additional filters does not make any sense to me. The fuel heater is worthless and a major cause of air leaks so throw it away. The other main problem is fuel hose air leaks. That would be taken care of with a hose from the tank to the fuel heater/pre-filter assembly. The only other hose that can leak is the short curved one between the pre-filter and the lift pump. It is not a major air leaker anyway. Seldom does that.



However, throwing the fuel heater away and replaceing the stock fuel hoses with hoses from LarryB will fix almost all of the 12 valve fuel supply problems. I have had no sign of an air leak since I installed Larry's hoses and threw away the fuel heater. The difficulty is trouble shooting the system if you don't know it. Throwing parts at it until the problem goes away like some do can cause a lot of frustration and get pretty expensive. The hose kit is cheap. Throwing the fuel heater away is free.

 

[TSPowell]

Joe,

I agree with you, I still might purchase the lines from LarryB. BTW, where did you get those pictures of the lift pump and heater/filter assembly on your readers rig pics. Im thinking about getting a Cummins service book, is that where they're from??

Thanks for the help!

 

[Joe G.]

My digital camera stuck down in there and click to see what I get. It took a few tries to get the picture of the lift pump. The cutaway pictures are from another web site.

 

[TSPowell]

Yeah, I was curious about the cutaway pictures. They look like you took a picture from a book page.