Originally Posted by 94GT inblockcam
Hey im a new member ......i was thinking if its not a fuel pressure prob.i would check the O2 sensor...see when the engine is cold the o2 isn used there is a consistant rich air fuel ratio sent to cyl. This is called open loop when the o2 heats up pcm goes into closed loop using it to adjust ur ratio accordingly if ur o2 sensor is sending a incorrect rich voltage signal causing the pcm to correct a rich condition that is not there and will cause it to lean ur fuel to much causing ur symptoms..volt meter should tell u
Well here's the instance I experienced a couple years ago. Startup just fine, ran like a scolded dog for the first 5-10 mins then if you tried to jab the throttle it would not go past 2 grand, ease into the gas it would rev as high as u wanted.
Put a fuel pressure gauge on it and when it would mess up, I was around 40psi at idle, jab the throttle and it would drop the pressure clear down to 10 pounds.
Turned out the fuel pump was clogged or something and was causing the pump to "burn up" and not supply enough pressure.
Changed it out, good as new.