GMC running rich

gmc
sonoma

#1

I have a 1995 Sonoma that runs rich at low RPMS. The Injection Manifold, O2Sensor and MAP Sensor have been replaced. The plugs foul on the #1 bank only. Compression is equal on all cylinders(150psi). Runs great on the highway. It misfires at idle. All new tune- up parts. In the last year the Crank Sensor, Cam Sensor, Fuel Pump and the Ignition Module have been replaced. Also the PCM has been tested. This was for other problems. Any suggestions? scouter


#2

Check the fuel pressure. Watch the gauge when the engine is shut off. If the pressure drops to zero to bleeds off in a few seconds think of a leaking injector or leaking fuel pressure regulator (into the vacuum line to the manifold). In fact check the vacuum liine to see if there is raw fuel in the line.