1989 GMC S-15 Jimmy. 4.3. Car was given to me because it was sitting in the woods. When the owner parked it, it was running rough and very rich. What I have done, ALL NEW plugs, wires, cap, rotor, map sensor, coil, temp sensor, complete exhaust from manifolds back, O2 sensor. Rebuilt TBI (seals, gaskets and filters). Removed and cleaned gas tank, lines and new filter. Compression check showed a HIGH of 159 and LOW of 151. Oil pressure by gauge is very good. Still runs rich. Will start and idle, when it gets a little warm if you touch the accelerator at all it dies. Will start back up if you hold pedal to the floor and blows black smoke and runs really rough but will idle after. I am lost. Have been out of work for a year and any help to keep me from paying a shop is GREATLY appreciated. Mike
Probable causes of an engine running rich are as follows: 1. Excessive fuel pressure can be cause by restricted fuel return line
2. Defective Oxygen Sensors.
3. Leaking injectors and fuel pressure regulator.
4. Coolant temperature sensor out of calibration.
5. Restricted air intake system.
January, 25, 2011 AT 8:34 PM
Fuel return line is not restricted. O2 sensor is new. Fuel pressure regulator is new.(Forgot to include in post) How do I calibrate the NEW temp sensor?
January, 25, 2011 AT 8:41 PM
Just install the CTS its job is just like the choke on a carbuerator till the O2 sensor takes over the loop
January, 25, 2011 AT 9:12 PM
What is "the CTS"
January, 25, 2011 AT 9:23 PM
Coolant Temp Sensor? Are you refering to the one in the intake manifold or the on in the block?