Engine/Transmission (1998.5 - 2002) Fuel Pressure: 6.5 psi @ idle, 0.5 @ WOT?

[RSchwarzli]

Hey guys, I installed a Autometer electric fuel pressure guage last night on my grandfathers 2002 6spd. It has 120,000 miles on it and the lift pump was replaced for a third time by the dealer about 30,000 miles ago with the new Mopar in tank relocation kit. As for the fuel filter, it was changed about two months ago.



After installing the guage, bleeding the lines, and having the motor running again, we noticed the pressure was low. After starting and stopping the motor we took it for a spin. 6. 5 psi at idle, at WOT in fourth, I saw the gauge hit 0. 5 psi!!! :--) Is this normal? Is there anything I need to check? Is it possible the gauge is faulty, or did I install it wrong? HELP!!!



Robert

 

[Jeff Knight]

Robert, I had the in-tank pump for awhile before I got rid of it. My pressure at idle was 9 psi max. I could pull it to 0 excellerating to speed on the highway. You might try changing the fuel filter to see if that might help. The pressure you are seeing isn't far from normal. Jeff

 

[16919]

The vp needs @least 5 psi at all times or you will burn it up. I'd add a pusher pump or change your set up to something aftermarket like Fass or Gdp.

 

[RSchwarzli]

Ok, we changed the fuel filter. We are now sitting at 8-9 psi at idle. Is this livable or does something else need to be done? Thanks!



Robert

 

[DavidC]

Personally I would not live with it. As stated above 5 psi is as low as you can go. Does it still go under that at any time?. Your kind of rolling the dice with low pressures. It is either money for a transfer pump or 1k plus for a VP44. Lowest pressure I would accept at WOT would be 8 (and that would not be for long).



Dave

 

[JKinney]

Ok, we changed the fuel filter. We are now sitting at 8-9 psi at idle. Is this livable or does something else need to be done? Thanks!



Robert

Robert, If you research that new intank pump on here, you will find that you actually have excellent #s from that pump. As alot of people have stated they only have 5 or 6 at idle and 0 underload.



That being said, I dont think there is a member on this site that understands dc's reasoning for installing these intank pumps, that are still providing lack luster preasure. ,

 

[Jeff Knight]

DC's stance at this point is volume not pressure. I can't understand where volume comes from at "0" pressure. Thats why after my 2nd VP I put the glacier kit on my truck. It never goes below 14psi. Jeff

 

[mec625]

fuel pressure

The pressure your getting is normal with the stock set up I changed my set up to the glacier pump GFS-392 and now have 19 psi at idle and no lower than 17 psi WOT good set up along with instructions

• 
  Mike/list]
  2002 4X4, 4" dual stainless exhaust , Glacier LP, hyperteck stage 3, Fuel Pressure guage with 5LB. warning light, K&N filter

 

[DavidC]

0 to me means the VP44 is using everything it is getting as there is no pressure difference between the lift pump and the VP :--) . Since the fuel pressure gauge does not read vacuum the VP could actally be trying to suck fuel as it is not being supplied enough.



Dave

 

[16919]

To each his own I guess. If you feel safe running no fuel pressure to your vp, just don't be surprised at the results. Industrial Injection, Blue Chip, Scheids, and above all, Bosch seem to feel that it takes a minimum of 5 psi to completely fill the plungers and adequately fuel the motor. I am in no way trying to provoke dispute, but this seems to be the general concensus of the TDR and high performance community.

Blue Chips website:



We proved on a dyno in 1998 that if you have 5 PSI, under load, you can make all the power available from a VP44. Do not use more than 12 PSI or you will diminish fuel delivery to the rotor and make the truck run worse at high RPM and possibly overheat and damage the fuel bypass solenoid. This diagnosis is only for the lift pump, but is necessary for the happiness and success of installing an injection pump and not having other issues down the road!