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Hi all, I have an 02 z track car with no emissions and headers cam etc. oem fuel system.
What happens is the car seems to pull power back at full throttle.
Idles fine and ok at mid throttle but not full throttle.
When I blip throttle the fuel psi drops a few psi. I think that’s normal.
My fuel pressure readings seem low according to the shop manual, should be at 55-62 psi with ignition on only but reads 36 psi ignition only and 45 psi engine running. After I shut engine off psi climbs to 60psi. Is this normal to climb to 60?
and could I have another fuel filter/regulator that’s low psi or bad? I’ve heard the quality control can be suspect on some of these fuel filters/reg.
I initially bought a gm replacement and now I have a tanks regulator/filter installed.
I did replace oem fuel pump and I’m on my second fuel pressure filter/regulator.
Any insight would be great! Thanks Brian
Last edited by Rockitansky775; Nov 11, 2021 at 07:46 AM.
Brian,
Where did you purchase the fuel filter/pressure regulator ??...if Amazon or Ebay that would be suspect...you may also have high resistance in the fuel pump circuit...high resistance equals low current flow equals low pump output equals low psi !!...you can try removing the pump connector and hotwiring the pump directly from the battery or another car battery if you can...if pump pressure is normal you'll have to do some detective work...I'll be moving your post over to the Tech section. BTW, if you get yourself an amp clamp off Amazon it would be easy to check current flow and a good addition to your tool box...the normal current flow should be around 6 amps or so key on. The power (gray wire) and ground (black wire) are on either end of the pump connector...pins A and D.
Ok Great! This is exactly the info I need and I'll bet its the problem. As all who owns C5s, wiring harnesses are very hard to come by, so I rebuilt mine TWICE! LOL Its not pretty. THANKS! Brian
I'm going through the same issues now. Saw my in car wideband gauge not richening on WOT. I also track the car. A few times I was on a 20 minute session not realizing that I have ran the tank down to 1/4 tank. I believe doing this burned up the pump and it causes low fuel pressure/lean condition. (glad I didn't hurt the motor thanks to the wideband)
my fix was new pump and Recetronix harness.
Maybe its the pump for you also, when taking hard corners and lower fuel levels prematurely wears out the pump. Just a thought.
I'm going through the same issues now. Saw my in car wideband gauge not richening on WOT. I also track the car. A few times I was on a 20 minute session not realizing that I have ran the tank down to 1/4 tank. I believe doing this burned up the pump and it causes low fuel pressure/lean condition. (glad I didn't hurt the motor thanks to the wideband)
my fix was new pump and Recetronix harness.
Maybe its the pump for you also, when taking hard corners and lower fuel levels prematurely wears out the pump. Just a thought.
Im a neophyte at tuning, what is wideband? Yeah running low fuel qty Ive heard causes all kinda problems, even limp mode on track. I did put a new Delphi Fuel Pump and on my second fuel regulator...ugghh, AC delco filter too.
I had a fire and burned up a lot of my wiring harness so my harness could be sketchy, but I did order a Racetronix FP wiring harness kit and swapping out the Fuel pressure damper, just because damper goes thru fuel system.
Im only reading 40psi ignition ON and with engine running.
I did watch the video for installing a Holley Terminator max and when you program that unit it gives you the option on 43psi or 60 psi when setting it up, I wonder if somehow my PCM is commanding Fp to run at 43? dunno. Good luck on yours, Brian
The PCM does NOT command the fuel pump to run at a certain PSI…with that burned up wiring you’ll have to check that out..a higher output pump is not going to fix your problem either.
If you have a stock fuel system then the fuel filter is your regulator located under the car in the tunnel. There is no adjusting that it regulates at 58-60 PSI. (Most LS based PCM)
Rail pressure should be around that or slightly under. I assume this is where you're getting you're reading from?? If you don't get a constant 58PSI car will lean out and blow up eventually.
Yes Im getting reading from FI rail drivers side. Ive used 2 different fuel pressure gauges too, just to make sure those are reading right and they are consistent. I might have a 3rd bad FP regulator, current one is MADE IN USA, or weak fuel pump. But It is a new FP, Delphi. THX for response!
Fuel pressure?
