3800SC Fuel Pressure Woes (Page 1/1)
Additivewalnut AUG 10, 05:20 PM
I'm chasing a lean condition / misfire under boost. Runs fine until I WOT, then it'll get to 3500 - 4500 and fall flat on it's face, gas pedal doesn't even do anything its missing so bad. Ep381 pump. LTFTs tend to hang out in the 16.4 range when attempting to drive hard, cruising was all over the place but generally in the negatives. O2 sensor voltage was anywhere from .1 to .7 and changed sporadically.

Fuel pressure with a brand new filter is as follows:

KOEO 45
Idle 40
Reg disconnected 50-55
WOT in neutral 52

I read on the 3800 forum that voltage drop is an issue with those cars and since I'm using the harness I figure I'd have the same issues. Alternator is pushing 14.6v, harness at the pump is seeing 13.6, I can do one pull in 2nd, then I noticed the voltage drop to 12.9 and I couldn't go WOT without the car missing horribly. Alternator after I stopped was down to 14.3 and the fuel pump voltage sat at 13v. Could I have a bad case of voltage drop causing the pump to not push enough fuel at boost?

There was some rust in the gas tank that got shaken out but it's not out of the question that the pump sock is clogged in some way.
Frenchrafe AUG 11, 03:27 AM
Hi there,
Your fuel pressure seems OK for the 3800.
I would check the MAF sensor.
I had problems with a MAF reading too low and giving a lean condition and misfire at WOT.
Cheers,
Rafe

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"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
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jelly2m8 AUG 11, 11:56 PM
Fix your misfire first before you start messing with what you posted being those are within Spec Fuel pressures.

These things are very picky with less than good plug wires I have found