Engine/Transmission (1998.5 - 2002) fuel pressure at 11 psi @ idle and white smoke??

[DHarden]

I bought this truck about 2 weeks ago and have no problems with it yet. It came with guages (fuel, EGT, Boost) as well as the 5 stage comp and 16 cm housing. The pressure has been constant @ 11psi @ idle with the comp on setting 1 through 5. I have heard that the pressure should be about 14 or 15??? Also, the first week I ran off road (high sulfur) diesel and I enjoyed the nice black smoke I left behind when I punched it. The next fill up I used low sulfur diesel and also added STP diesel additive. After a few days I noticed that with the comp at level 1-3 I got white/slight gray smoke and on 5 I got dark gray/black smoke. I know that the high sulfur burns black but I have seen in other post that the white smoke and low psi is early sign for a bad lift pump





Any ways to check the pump?

How can I make sure the Fuel pressure gauge is setup right??



Thanks

 

[RJOL]

11psi might be a little low for idle. What are your pressures when your cruising, and when you put your foot in it?



You will get white smoke, sometimes on starting as it usually means a little unburned fuel. White smoke all the time is not normal. Have fun...

 

[DHarden]

After watching the fuel pressure during acceleration and when I get on it it seems to only drop about 2 psi. What should the psi drop be from idle to getting on it? Thanks

 

[DHatfield]

You should have no less then 10 PSI at WOT and if not that I would think you would still be okay as long as it does not drop below 5 PSI at WOT.

 

[Sixpack]

This is from:

Proper Order for Upgrading ISB Engines

by Ted Jannetty

Jannetty Racing Enterprises Inc.



Fuel Pressure: or pressure created by the electric fuel pump that carries the fuel from the tank to the filter then on to the injection pump. This has become a very important gauge on the ISB with all the fuel pump failures that have occurred and cause drivability issues. This gauge is not very exciting but when there is a problem it becomes very important in diagnosis, plus it can save a very expensive injection pump from failure due to lack of lubrication and cooling.



Average Pressures: stock truck (in pounds per square inch)



Idle – 10 to 14 psi

Cruising – 8 to 12 psi

Pulling a hill with trailer – 8 to 9 psi



Absolute minimum pressure is 8 psi; anything below that and you need either a new lift pump on a stock truck or an upgraded fuel system on a modified truck. More on this later.







Proper Order of Upgrades

 

[darkhorse]

I too have been concerned about fuel pressure. I have a factory service manual for my '01. It states that the idle pressure at the test port entering the filter should read no less than 10 psi. the pressure at the test port on the vp44 should be no more than 5 psi less than the first reading. Further reading on this forum leads me to believe that while lower pressures under load may indicate a weakening lift pump, damage to the vp44 does not occur as long as there is positive pressure.