Problem first started back in march, while driving, the car lost all power and I coasted in my driveway. it would start and stall immediately. Thought it might be a fuel pump because it acted like it was running out of fuel and would not let me touch the accelerator without it cutting off did not have the diagnostic equipment at home to check it. I took the car to the shop where I work and replaced the fuel pump and it runs exactly the same. has 38-42 lbs fuel pressure at all times, no codes at the time, I started replacing parts, I replaced the distributor, replaced the map sensor, throttle position sensor, cap, rotor, plugs, wires, knock sensor for a code 43 "probably just knocking because of running so poorly", replaced the computer and mem-cal or prom chip per alldata bulletin, engine coolant temperature sensor, lower intake gasket set, throttle body gasket, runner gaskets, oxygen sensor, checked the egr valve and solenoid, got pinouts of the ecm connector and checked all inputs and outputs into and out of the ecm including power and grounds, checked thoroughly for vacuum leaks. I think I might have some malfunction with the fuel injectors maybe? I need some ideas because I have done everything that I can think of. The car runs like crap and backfires and stalls, absolutely cannot be driven above idle, the car will idle fine but gets worse as it warms up. I have even drained the gas tank and replaced the gas!! 1990 IROC-Z 305 tpi

 

Good gawd man. Sounds like you have replaced everything BUT the injectors. Im not a master mechanic, all I can offer you is this advice. Break it down elementary style....Fuel, Air, Spark......where is it failing?

Have you checked timing? How many miles on the engine? Camshaft?

Good luck, I would have gotten violent by now...............

 

workin at the dealer, i have gotten bitten in the butt a few times and had to break things down to elementary basics and figured it out. I have checked the timing and set it to spec, then i decided to later loosened the distributor so that I could turn it while running to see if I could make it run better. I checked the catalytic converter with a backpressure gauge and that is good, While looking at the scan tool, I notice 2 things happening, first off, the knock sensor is working correctly and isnt showing a knock and isnt retarding the timing, but the oxygen sensor shows that it is running lean "350-400 mV" however it smells like it is running ungodly rich, when I step on the gas, the timing is supposed to advance, but it retards and backfires.

 

When was the last time you replaced the inline fuel filter???? Try the simple things first you already replaced a boatload of parts.

 

I replaced the fuel filter when I put the fuel pump in, and when running, the car stays between 38 and 42 psi so I know that my pressure up to the fuel rail is good.

 

The fuel issue looks good, so the next place to check is electrical.

 

have you checked the injectors with a noid light?

also, it sounds like it could be an issue with the fuel pressure regulator. mine went bad and it ran so rich that there were fuel droplets comming from the tail pipe. it would start and stall immediatly and the only way for it to fire was to hold the throttle to the floor (86 tpi) and it ran poorly. it failed because the vaccum diaphragm inside got stuck to fuel contaminants. since youve basicly replaced eveything else, might as well try that.