1991 Chevy Truck engine light

Tiny
RUFFNREADY5
  • MEMBER
  • 1991 CHEVROLET TRUCK
1991 Chevy Truck V8 Two Wheel Drive 150000 miles

I thought I bought a truck with bad head gasket. It had no thermostat and after driving it for about 10,000 miles it showed the signs. I pulled it down to the heads and it looked like just the rear of the intake gasket was leaking. Had the heads completely redone, and replaced anything that looked worn. New belt, hoses, cap, roter, plugs, plug wires, pullys, oxy sensor, throttle position sensor, oil, oil filter, air filter, pcv, fuel pump, temp sensor, temp gauge sensor, thermostat, and loomed all wires. The truck starts and runs great until warms up. The truck has never used oil or smoked and ran really strong before repair so as to think the bottom end has some miles left in her. After it warms up it runs really runs rich then, runs like crap, then dies. The engine light comes on but with a jumper wire only show the "12" code. I don't have all the electronic diagnosis equip-ment to check by the book so looking for which things to replace first. I hate to spend much more than I have to. Map sensor? Knock sensor? EGR? EGR valve?
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Saturday, October 25th, 2008 AT 12:33 PM

1 Reply

Tiny
2CEXPT
  • MEMBER
Hi ruffnready5 and welcome to 2carpros

Running rich:

Probable causes include a bad O2 sensor, excessive fuel pressure (bad fuel pressure regulator or plugged return line), leaky fuel injectors, dirty air filter or restricted air inlet, or a defective coolant sensor that prevents the engine management system from going into closed loop mode. Check the EGR could be leaking and computer throwing fuel at it to compensate
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Saturday, October 25th, 2008 AT 2:50 PM

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