Engine/Transmission (1998.5 - 2002) another fuel pressure question.

[RHillman]

I just installed a fuel pressure gauge with a new fuel filter just to eliminate any problems. At idle the pressure is at just about 10 when driving normal it is at between 6&7 but a WOT it drops to almost 3. After reading many posts I don't think this is right. The truck has 70,000 miles on it I bought it used at 65,000. I am pretty sure the truck is stock. One other question the boost guage peaks a 24 is that stock the guage is hooked up with the boost bolt inb the manifold? Let me know if it you guys think it is the lift pump or any other suggestions to check it out before I bring it to the dealership. Thanks in advance for any help.

 

[PC12Driver]

That's about what I found when I installed my FP gauge. Since you just changed the filter, I'd say it's the lift pump.



Are you still in the 5yr/100k mile engine warranty? With no mods the LP should be covered.



24 psi seems a tad high, especially for an auto. I think most de-fuel about 21psi. Could be gauge error, maybe not. If it is 24psi, your 'gate could be stuck closed or modded to prevent opening. Also, 24psi would have set an overboost code and caused the truck to defuel (maybe limp mode?) if there wasn't some sort of boost fooler or electronic power enhancement installed.



(btw, fill out your personal signature with your truck's info. That way it shows up when you post. We get into that sort of thing around here, and it helps with troubleshooting too. It's under Discussion forums, user control panel)

 

[Hohn]

Yes, your LP is probably dead.



And also a stock truck will hit 24psi when towing, but the wastegate should be able to dump it down to 21 or so. HO trucks will defuel to keep boost under 26 (if the ECM sees it), while other 24Vs will defuel at 21 or so.



Your WG may be stuck closed.



jlh

 

[HNeumann]

Fuel pressure

I just installed a fuel pressure gauge today. My 1998. 5, 24 valve shows 10 psi at idle, drops to 7 at 2000 RPM. Is this not good? don't know where it should be.

Hal

 

[Jim Ross]

My '01 with AT and DiPricol gages: factory boost stopped at 18psi until I installed a mod to the wastegate, now it runs up to about 29psi..... no problems.

My fuel gage normally reads about 20-22 at idle and never below 15 when running empty at 70mph.

I have had to replace my lift pump one time(so far) in 64K miles, but early on, I installed a Carter elec pump to "help" the factory LP.

Lately, I have had a problem develop in my fuel gage where it keeps getting air in the line that comes from the inj pump (schrader valve). This cause the gage needle to just go crazy! I have what sounds like the same set up that you have: DiPricol gage with an isolator and sending unit that powers the gage via anti-freeze in a small plastic tube running to the gage.

How or where am I getting the air that keeps getting into my fuel gage feed line? I can bleed out the air in the line between the inj pump and the isolator, but after a few miles, it is back in there causing my gage needle to go nuts again! Any ideas?

 

[jeepit]

Mine is reading 12 at idle, 10 cruise, 8 wot. I think I'm ok??