I have a '96 GMC Jimmy 4.3. I put a new fuel pump and tank in; also, a new cap and rotor. When it's cold, it won't start.

I have a ’96 GMC Jimmy 4.3. I put a new fuel pump and tank in; also, a new cap and rotor. When it’s cold, it won’t start.

I have a '96 GMC Jimmy 4.3. I put a new fuel pump and tank in; also, a new cap and rotor. When it's cold, it won't start. When it's warm, it starts, then idles fine, but when you give it gas, it runs rough. I put the code reader on it and it's a random mis-fire. Any ideas?

I noticed you didn’t say anything about plugs and wires. A cap and rotor usually doesn’t do much good with out them. Change those and I bet your luck changes.

Matthew Vaughn
O’Reilly Auto Parts

If this is a Central Port Injection 4.3 (VIN W) you may be experiencing injector poppet failure. A new-improved version of the CPI injector module made by SMP is available through your parts supplier. If yours is a Throttle
Body Injection 4.3 (VIN Z) you may want to check ECT sensor or MAP sensor.

Jim O’Neill
Chino Autotech Inc.

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