Engine/Transmission (1998.5 - 2002) fuel system troubles

[darkhorse]

I just finished replacing my injection pump that died on New Years Day. Got her bleed out & fired up. Let it idle outside while I put tools away & packed my stuff. Got in & drove down the mechanics drive & she died again after only a few hundred yards. I couldn't restart it & was seeing only 15 psi or less on the gauge. (usually 20). My mechanic friend towed the truck back up beside the shop & for giggles I tried one more time. Fuel pressure was 20 So I cranked the motor & it fired up. I let it run several more minutes then started back down the drive watching the fuel pressure gauge. Almost immediately I saw the pressure slowly fall off & when it got to about 5, the motor died again. I changed the filter but that had no affect on pressure. When I bump the starter, I can hear the FASS pump running but the pressure comes up very slowly & only to 5-8. I'm puzzled & a bit frustrated. What's up? Any ideas would be appreciated.

 

[OPoole]

On the VP-44 is a return fitting (in front of fuel feed fitting) with a spring inside could be open maybe trash and returning too much fuel. Some reman VP-44 comes with a new one? some don't.

 

[darkhorse]

On the VP-44 is a return fitting (in front of fuel feed fitting)



Thanks for the input, Olie. I've been wondering about the return valve. I didn't get a new one & I had a hard time wrestling with that little bugger getting it straight & not cross threading the fitting. At one point the thing sproinged out of my fingers & the valve dropped to the floor. #@$%!

 

[darkhorse]

I replaced the fuel return fitting today with no change in fuel pressure. That was a $55 experiment that failed. . The FASS pump sounds like it's running good but the pressure rises slowly & only to between 2-4 pis. I have a new filter in place so that's not the problem. I guess I'll have to have it towed back into the garage tomorrow & start going through the fuel system from front to back looking for the problem. Is the pressure relief valve in the pump leaking? Is the fuel strainer clogged? The new draw straw sucking air? I do know the fuel filter I just pulled out looked as if it were new.

 

[LowFly]

I replaced the fuel return fitting today with no change in fuel pressure. That was a $55 experiment that failed. . The FASS pump sounds like it's running good but the pressure rises slowly & only to between 2-4 pis. I have a new filter in place so that's not the problem. I guess I'll have to have it towed back into the garage tomorrow & start going through the fuel system from front to back looking for the problem. Is the pressure relief valve in the pump leaking? Is the fuel strainer clogged? The new draw straw sucking air? I do know the fuel filter I just pulled out looked as if it were new.

Some times you cant see whats clogging a filter.



BUT i would check the basics first here:



Make sure your gague is not telling you lies. If you have an isolator, i would check and rebleed both sides.



If you are only getting 2-4 PSI... i feel you have lost prime in our pump. Crack the fuel filter ONLY loose and run the pump. When the pump changes tone, tighten up the filter and let run to move any extra air out of the pump.



Stupid quesitons..... BUT do you have fuel in the tank? You would be suprised on how many issues this solves!

 

[darkhorse]

Some times you cant see whats clogging a filter.



BUT i would check the basics first here:



Make sure your gague is not telling you lies. If you have an isolator, i would check and rebleed both sides.



If you are only getting 2-4 PSI... i feel you have lost prime in our pump. Crack the fuel filter ONLY loose and run the pump. When the pump changes tone, tighten up the filter and let run to move any extra air out of the pump.



Stupid quesitons..... BUT do you have fuel in the tank? You would be suprised on how many issues this solves!

Thanks for chiming in Dan. I used your video's to change the IP. They helped a lot. I have about 1/2 tank of fuel according to the gauge which has always worked so far & that's consistent with the mileage from my last fill. There is a new fuel filter in the canister now. Ever since I got a new ground to the battery my Westach fuel pressure gauge has read a very steady 20 psi that I can only draw down about 2 psi with heavy throttle. Just to be sure though I rigged up a mechanical test gauge this afternoon. I'll use it tomorrow if you tip on bleeding from the filter canister fails.

 

[darkhorse]

Stupid quesitons..... BUT do you have fuel in the tank? You would be suprised on how many issues this solves! [/QUOTE]



Dan, it turns out this was not such a stupid question. It seems my fuel level gauge was stuck at about 5/8. I then ran the tank dry bleeding out the new IP. I showed 20 psi all the way down the garage drive to the highway then :{ the pressure dropped off. The fix turned out to be easy but I wish I'd checked the tank sooner.

 

[LowFly]

Dan, it turns out this was not such a stupid question. It seems my fuel level gauge was stuck at about 5/8. I then ran the tank dry bleeding out the new IP. I showed 20 psi all the way down the garage drive to the highway then :{ the pressure dropped off. The fix turned out to be easy but I wish I'd checked the tank sooner.

COOL! Easy fixes are always good..... even though they sometimes bite you in the rear! haha... . Glad you are up and running! Let me know if you need any more assistance.....

 

[darkhorse]

COOL! Easy fixes are always good..... even though they sometimes bite you in the rear! haha... . Glad you are up and running! Let me know if you need any more assistance.....

Thanks, Dan. I'm good for now unless you have a spring that would bring my 20 psi down closer to 15. Now I'm off chasing electrical gremlins & pondering what to do about a fuel level sensor gone bad.

 

[Gary - K7GLD]

Thanks, Dan. I'm good for now unless you have a spring that would bring my 20 psi down closer to 15. Now I'm off chasing electrical gremlins & pondering what to do about a fuel level sensor gone bad.

IF with the 20 PSI spring you can pull it down to 2 PSI under full load, are you SURE you'd want to drop supply PSI down to 15?

 

[darkhorse]

IF with the 20 PSI spring you can pull it down to 2 PSI under full load, are you SURE you'd want to drop supply PSI down to 15?

That 2 psi was as the pump sucked the last of the fuel from the tank. Now with a full tank I can't pull it down 2 psi from the normal 20 it reads under no load.