Help!!!!
Are you able to monitor fuel pressure at WOT (during greatest fuel system demand)? I ask because I didnt see an actual fuel pump listed in your parts-replaced synopsis.
Also, have you tried backing the timing down a hair?
Good luck.
I have not replaced the Fuel pump, I do have a gauge on the fuel rail, about what do you think the pressure should be at wot? Also, the timing is exactly where it should be for stock timing on a 94 gt. It pings so bad some times, I thing backing timing down a hair wouldn't be enough. On cool mornings, the car seems to run w/o pinging, but as it nears normal op temp, then it will ping. If I put regular unleaded in it, it will ping at 1/2 throttle!!!! I'm mystified!!!
Pressure should be 38 PSIG at WOT (when you check fuel pressure with the vac line removed from the FPR, you're simulating a WOT condition with regard to the FPR bypassing fuel).
That part about the conditions is interesting. A couple thoughts: Have you installed a real temperature gauge to see how hot you're engine actually is? The stocker is pretty to look at, but not much else. You could be seeing an onset of a preignition-type situation due to crap in the CC's and a hot engine.
I'd note that fuel pumps tend to show their weakness when they get hot (the diaphram gets loosey-goosey) but they tend to degrade quickly - it does not sound like yours is.
You might want to search "Seafoam" and see if that's something you'd like to try. I'm leery of those products but so many folks have had success with it (and a few have claimed that issues arose after using it)...............
Because the processor on these cars is load based, that's good that you commented on the part throttle aspect (though with a more volatile fuel being used). Your timing-advance can actually be higher at part throttle than when you press deeper into the pedal. This doesn't help pinging.
If you haven't, please pull codes. Codes can be stored without illuminating the CEL. But something like a lean (O2) code could be telling.
Random thoughts.
Good luck.
Today I checked the Fuel pressure,w/ Vac line removed from the regulator, It consistently read 38 psi, however, w/ the Vac line plugged back in, I'm getting about 30 psi at Idle and it increases as you step on the petal, up to about 38 psi at wot. I guess I should pull codes next.
That's normal. FP can be thought of as inversely proportionate to acceleration (at idle, it's 30ish. At WOT, when manifold vac is low, it jumps to near 40 PSIG). Were you able to view fuel pressure at WOT when the car was actually pinging? Testing in the garage doesnt put any load on the engine (where a failing pump shows that it cannot deliver the needed volume).
Code retrieval sounds like a great plan.
Good luck.
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