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  1. #1

    Default 1988 Chevy 3500 running rich

    I have a 1988 Chevy 3500 with the 7.4 and it has the EFI on it. The other day I was driving down the interstate and my truck started sputtering. When I got back into town I noticed that it was putting out un burnt gas out of the exhaust. I was wondering if anyone has any ideas on what would be causing this.

  2. #2


    Try testing the ECT(Engine Coolant Temperature) sensor on the front of the intake manifold. Use a multimeter and check the resistence value of the sensor (not the lead) with the engine cold, halfway warmed up, and then again after the engine has reached operating temperature. The resistence value should start somewhere around 1000-1200 ohms cold and then end somewhere around 100-300 ohms at operating temp. If there is a drastic difference from these values, then the ECT is bad and needs replaced. With the problems your are describing, if it is the ECT, i would probably expect that maybe the resistance will be around the same regardless of cold or operating temp. Let me know if this works. If not, i can suggest some other possible causes.
    2002 Silverado K1500HD (NEW!!!!!!!)
    1999 S-10 Blazer
    1990 K1500 5-spd TBI 350.
    2001 Monte Carlo SS Pace Car

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