Low fuel Pressure & Check engine light

[xxRillixx]

I've had a check engine light for about a month, and the error is in Quadrant 4, some kind of electrical / power error (some kind of short). Would this have anything to do with unsteady fuel pressure? The car runs fine till the weather is warm, and i sit in traffic for a while. I just installed a new pump, and an adjustable fuel pressure regulator. Its the worst after i drive it for 30-45 min and then let it rest 5-10 min and try to drive again in the heat (Only this past couple days). When the car is off it primes fine, 35-50 psi, but once i start- it will slowly decline till i throddle it or it gets to 3-4psi and will shoot up to 20's psi and decline a couple times till it stays at 3psi and stalls.

-Regulator doesnt seem to be doing much to alter the psi... and i dont think the pump is going out because it is trying to keep up... just feels like too much fuel is being dumped back into the pump.

Any ideas would be greatly appreciated! Thanks in advance.

[Injuneer]

Your 93 has DTC codes for something called the "quad driver modules", and there are three different modules - #1, #2, and #3. Without the exact code (DTC 26 = #1 - AIR, EEC and EGR; DTC 27 = #2 - tranny controls; DTC 28 = #3 - fans and A/C), its impossible to even guess at the problem. There is no Quad Driver #4, so you need to go back and get the correct code, by flashing it in the SES light.

None of the above would cause low fuel pressure. Fuel pressure is not controlled in any way by the ECM. Its controlled by the fuel pressure regulator, which is strictly a mechanical device. You either have a faulty pump (overheating?), plugged fuel filter, pump installed incorrectly (wired wrogn, hoses reversed, hoses not clamped) or the fuel pressure regulator is bad. Pull the vacuum compensation hose off the regulator and see if it has fuel in it.

[xxRillixx]

There wasnt any fuel in the vacuum line, and the FPR is brand new (not saying it couldnt be faulty, but not likely). I just changed the fuel filter not too long ago when i had the problem at the end of summer. Ive also recently changed the fuel pump.

Its just when it gets hot outside and the car sits for a while (ie in traffic). Would the car being above 'normal opperating tempature' affect the Fuel pressure? It really doesnt get that hot, probably 210 220 -> at the most. Ususally is right around 180-200. 200 sitting, 180 when its moving (electric gauges).