Engine/Transmission (1998.5 - 2002) Unresolved fuel delivery: VP44/Lift Pump

[rabsyeeha]

Ok, I am kind of at a loss here. My VP44 went, and I replaced it about a month ago. The pressure remained kind of low, and some of the simptoms indicated that the lift pump may be going as well - again. So I replaced it last week, and the pressure seemed to be back up to normal. Now it's kind of low again. Lower than I care to have it anyhow. On acceleration, it drops to 8. 2 - 8. 6. Although it is more stable now.



I have a digital gage, which is relatively new, same with the sending unit. Both seem to be working ok. The cam position senseor was replaced lat year due to a code, so I left is alone when swapping the VP. Aside from checking the fuel lines for air leaks/suction in more detail, I am not sure what could be causing the lower pressure. When cold, the engine seems to rev a bit uneven, though onl yin sound and not so much in feel.

Any thoughts?



A related question for the fuel gauge reads. At start-up/iginition on, woul dit typically read high first and then drop as the lift pump kicks on, or start low, rise and fall again if she's not actually started/turned over right away? I wan't say what mine does just yet, to illiminate any confusion.



Thanks again. Kudos to Midwest Fuel Injection.

 

[RJWEST]

fuel pressure follows voltage,
Heaters on, voltage low, fuel pressure low...

 

[DCreed]

fill in yer sig/profile it'll help us help you!
as the truck turns on the lift pump runs a couple secs to "prime" then stops ,it starts again when the computer senses truck is running. hows the filter? the stock type pumps, especially when mounted on the engine, dont put out much psi. as long as it is NEVER less than 5psi ,it should be fine.

 

[rabsyeeha]

I will check the voltage and update the truck profile. For now it's a 2001 all stock, except for an Edge EZ and AFE intake/filter.

Thanks.

 

[WWhite]

Checking fuel press

Check fuel pressure with a low pressure gauge to check your dig. gauge.

Make sure your fuel filter is clean when doing this test. If not sure replace it.

I like to move the fuel pump down by the tank.

Geno's make a reloction kit, has everything you need.

William

 

[rabsyeeha]

Thank you. I'd like to relocate the filter when possible.

 

[JKinney]

Thank you. I'd like to relocate the filter when possible.

I think every thing is normal, I saw alot of oem lift pumps do what your describing, ie: pressure was at 12 idle now at 10 and drops to 7 or 8 psi u/l. and moving the pump to the frame only band aids the problem. If a restriction does develop, the pump will cavitate.

 

[JAG1]

I had your same situation. Went an got rid of all the restrictive banjo bolts on the fuel lines. Kit from Genos or Vulcan performance. Man what a difference after it was done. PSI stays at 14 and will not fluctuate at all. This is with oem pump reloated too.



I think the banjo bolts also may cause some cavitation in the fuel too.

 

[rabsyeeha]

That makes a lot of sense. So what did you replace the bajo's with, the kit from Geno's? I'd love to try it. Thanks.

 

[WardJ]

That makes a lot of sense. So what did you replace the bajo's with, the kit from Geno's? I'd love to try it. Thanks.

Yes, it comes with everything you need. Order the 'Relocation Kit'.

 

[JKinney]

I did the vulcan kit right from vulcan clean to the vp44 and still got cavitation, average oem pump life till cavitation: 12 months. I installed a draw straw last spring but also went with a glacier system so I dont know if the tank module had been the culprit. I went through 4 oem pumps, with two on the frame before I threw it all away.

 

[rweis]

I have been inside my fuel tank several time in the past 6 months. Something members often do not check is the fuel pickup in the tank. The fuel pickup in the tank has a gauze screen filter around the pickup. Mine was really badly cloged first time I went into the tank. While you are in there check your fuel level float for deterrioation and the fuel level rheostat.



Bob Weis

 

[rabsyeeha]

Will do, thanks. I'll let you know on the progress.

 

[darkhorse]

I have been inside my fuel tank several time in the past 6 months. Something members often do not check is the fuel pickup in the tank. The fuel pickup in the tank has a gauze screen filter around the pickup. Mine was really badly cloged first time I went into the tank. While you are in there check your fuel level float for deterrioation and the fuel level rheostat.



Bob Weis

Bob, I was just in my tank a few weeks ago. It's an '01. 5 & it didn't have that gauze screen at all. It now has a Vulcan draw straw any way.

 

[DGerth]

Sir,

I recently went thru this drill and this what my fix turned out to be. Are you using an isolator for your gauge? Mine was low on antifreeze in the line on the gauge side and had lots of air too. I purged said line and isolator. Problem cured. Pressure steady and constant. I am using a GDP pump and ISSpro gauges on the frame near the tank. 20lbs @ idle,

17lbs @wot. Just a thought.

dg

I have an 01 with 150K, 2nd VP, new GDP system. Was using stock LP at the tank for 140K.