Engine/Transmission (1998.5 - 2002) Lift pump questions

[ccurtis]

I was trying to check the pump pressure at the filter inlet and introduced air to the fuel system. When I tryed to refire the truck it started and ran for about 10 seconds and then died. I have cycled the key and bumped the starter to try and get pressure again with know luck. The truck will not restart after this. Is my lift pump bad or am I doing something wrong? Any help on this would be greatly appreciated.

 

[CoastyAV8R]

If your lift pump is bad or weak it wil make it hard to start. Have you opened up the filter housing to see if there is any fuel in there? I had pretty much the same thing happen to me and once I put some fuel in the filter housing from a fuel can and it reluctantly started. My lift pump was intermittent at best so it wouldn't fill up the housing. I'm sure more info will come your way, this is just my experience...



Good luck,

Pat

 

[ccurtis]

Yes, I open the filter housing and it was full of fuel.

 

[Ncostello]

If your sure your lift pump is putting fuel in the system, then bumping the starter about 3-4 times should purge as much air out of the system as possible. Since it ran a little, some air most likely got in the HP lines etc. Then its hold the pedal at about half throttle and crank for bursts of about 10-15 seconds at a time with time in between to cool the starter. It will probably hesitate, fire, run rough and eventually come out of it. Dont be afraid to crank on it a little while. But never over 30 seconds. Injector install instructions said to hold the pedal at half throttle. I didn't think that would help but it did on mine.

 

[Ncostello]

Also as a note, if your lift pump is in anyway so weak as to not be able to put any kind of pressure out (like mine was) you will probably not be able to get the air out and it will not start period. I found this out the hard way and ended up installing a new lift pump. Then it was all good after that point. My lift pump was so bad, I took off the test ports on the cannister housing to bleed any air in the system but to no avail. It would not even put a tablespoon in the cannister. I was dead in the driveway.

 

[FDziurda]

Air Bleed

If you got air into the injector lines, you will need bleed the injector lines. I think the service manual says loosen lines for cyls 3, 4 , & 5 and crank until you get fuel. Manual says to be careful because of very high pressure (17,400 psi). The injector pump is not self priming, which is why you have to loosen the lines.



I 've had to do this once when changing the fuel filter.



Good Luck,



Frank

 

[Smills]

If you can hear the lift pump run when you bump the starter than most likely its working. After bumping the starter the pump will usually run for about 15 sec. You probably need to crack the injector lines since your filter is full. Just crack them and crank you will see air come out of the lines when cranking once you see more fuel than bubbles than tighten the lines and crank her up again should fire. If you have any question on cracking the injector lines do a search on previous post and that should get you more detailed info.



shane

 

[Ncostello]

Just as a note, thats all my lift pump did... run. It made lots of noise, and infact sounded alot like my new one... except it wouldn't pump fuel at all. Don't take its noise making ability for granted. But if you say the cannister is full, it must be working OK just based upon that.



I forgot to mention cracking the lines. I've never had to do that... yet on this engine. When you crack the lines, do you bump the starter and wait for the lift pump to push fuel/air out of the loose fittings?? or do you have to be cranking the engine the whole time your watching the lines bleed air. Just wondering cause I'd almost need an extra person to crank the engine while I watch the lines. Plus I wouldn't want it to fire up while I'm trying to tighten the three lines. Could prove to be very, very dangerous at 18000psi. Dont want no part of that.

 

[Smills]

Ncostello



You have to be cranking cause the vp44 doesnt inject fuel unless you are cranking and it is kinda of a 2 person job with the lines. Most the time it wont start with 3 lines loose. It will start once you tighten those lines and then crank again. It might take a few times depending on the amount of air trapped in the lines. If you search cracking the lines it will bring up lots of good info but the job is pretty basic.



shane

 

[TowPro]

Once I had a Pressure test gauge on mine, with about 3' of 1/4" hose so I could see it in with the hood shut, through the windshild. No matter what I tried (including a new lift pump) it would not start. When the lift pump would start to suck fuel, and the pressure would go up, the fuel would pressurize the air in the 3' line. When the pump would stop running, the air pressure would force the air back through the lift pump and it would loose prime. Sounds "off the wall" but as soon as I removed the test gauge, the pump filled the filter and the truck started right up!