Major Misfire, Help!

I recently purchased a 1993 4x4 s10 blazer with 168000 miles on the 4.3 Vortec that to say the least has its issues, but one at a time i guess, i am currently trying to fix the misfire i have in the engine, it has and extremely rough idle, pulsating check engine light, no power, drinks gas, blows white smoke with a black exhaust puddle, randomly runs better only to get worse soon after, and i am soot fouling (all) plugs. now for what i have tested and replaced, i have replaced the alternator, oil, filter, plugs, wires, coil, cap, and rotor. i have ran two cans of Seafoam and injector cleaner through the gas and a bottle of Z-Max in the oil. i have done a compression test which was in spec, checked throttle body plate and was dirty but not enough to do this but i cleaned it anyway, done a coolant pressure test with a very small leak in the intake manifold (which i already new about), voltage tested my o2 and said it was running to rich, fuel pressure test which was on the very low end of the spec but still in spec, and i was told it recently had the exhaust redone (cant prove yet). and don't know if its the same problem or not but on cold mornings i was losing power to my computer and dash randomly going down the road when i tried to give it gas then it would get worse and wouldn't run at all and I'd have to shut it off and restart it, so i checked all body grounds (all were good) and got a new battery (old 1 was bad anyway) and hasn't come back YET. SOS, HELP Please!?!:banghead:

Bad nut kit and leaking regulator.

Check the engine temp sensor.

don't want to be rude and ? you but what does an engine coolant temp sensor have to do with misfire and what do you mean by bad nut kit?

If the ECT sensor is indicating a lower than actual temperature, the ECM will richen the mixture. If the "nut kit" or fuel pressure regulator are leaking it will run rich also. The "nut kit" is actually the fuel pressure line and fuel return line that connect to the fuel injector and fuel pressure regulator inside the plenum.

Is there fuel in the oil? Are plugs #3 and/or #4, (middle plugs on each bank) fuel fouled? If so the "nut kit" could be the problem.

all the plugs were fouled including the middle cylinders and yes when i got it it had fuel in the oil that's why i did an oil change.

I would start by checking fuel pressure and leakdown. Key on, engine off, fuel pump running, fuel pressure must be 55psi to 61psi. Pressure must remain above 50psi for 3 to 5 minutes after the fuel pump shuts off. Post your results.

don't want to be rude and ? you but what does an engine coolant temp sensor have to do with misfire and what do you mean by bad nut kit?


How rude! ;)



Old master got i for ya.



Post a pic of the plugs.