Hello I Have a 89 GMC 2500 and it hesitates when you start moving but once you get past the intial start it runs fine. You can hear it miss when its idling also. Anyone know what causes this?

Asked by Mar 10, 2014 at 07:20 PM about the GMC Sierra 2500

Question type: Maintenance & Repair

The following has been replaced: Spark plugs and wires, Distributor cap and rotor, oil pressure gauge switch, fuel filter, and  inspected ignition cables

3 Answers

9,725

? Spark or fuel. Is it flooding or leaning out. If it's lean Check the injector spray pattern. If it looks weak check the fuel pressure, I think they are 10 to 13 psi. If the fuel is good check your plugs and the spark at each plug. It may be the pick-up coil or weak ICM. If it's rich (flooding out) the pressure may be too high, NFG regulator in your throttle body???

The Injectors sputter spray when you first apply the gas then it sprays as it should. The spark plugs are clean. I will check the coil and ICM and NFG and see if that's the problem.

9,725

LOL, NFG = No F$%#in Good. Check the spark at the plugs -> pull them out one at a time and ground them to the motor and start the truck. Should see a bright blue spark. If the injectors are spraying incorrectly when the sputtering happens that's were I would look. Once you get it moving it's good but what about if you give it lots of gas, like if you were going to pass someone. That would indicate low fuel flow, plugged fuel filter, partial failure of the fuel regulator or weak pump. Check the first two first as the in tank fuel pump is a dirty job.

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