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Richard 2/28/2020

1995 Buick Park Avenue Base 6 Cyl 3.80L


Why does motor surge trying to go steady speed

RPM gauge jump up & down like fuel or air , changed fuel pump ,coil packs and module

1 Answer


Jimm 2/29/2020

Before replacing any parts - always thoroughly test and diagnose. For example - what was the fuel pressure at the fuel pump outlet and also at the fuel rail at the engine? What was the coil output voltage? What is the fuel filter condition? Is the filter blocked?

In addition with an unknown cause or issue - always first check and test the basics; air, fuel, spark - also before replacing any parts.

Check the air intake system for any leaks, damage or cracks - including the engine vacuum hoses. Replace as necessary.
Next - check the fuel system for correct pressure and volume. You will need a fuel pressure gauge for this step. Obtain this as a loaner tool from any local auto parts stores.
Then - check for correct spark; both at the coil secondary (output) side and at the spark plugs.

Once the basic engine conditions are diagnosed and corrected as required, only then can further inspection and diagnosis proceed.


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