1999 Chevy Sub with a 5.7. Engine has 113000 miles. Engine runs fine until I mash it to pass someone, it cuts off like it has a governor. If I let off it continues to run great. Not sure if it is related but when stopping and putting it in park the RPM will race up an couple hundred more RPMs for a moment. Engine light has not come on either. What could be the cause of this?
Hello and welcome to Just Answer,
Your symptoms seem to point to a lack of fuel, typically caused by a clogged fuel filter or weak fuel pump. I would first replace the fuel filter as a maintenance concern and test. If problem continues have the fuel pressure tested, should be in the 55-60 psi range.
As far as the Idle concern a throttle body cleaning would be the first place to start. A dirty throttle body can cause the Idle air control valve to have a hard time achieving the correct idle.
To clean the throttle body a solvent such as carb cleaner and an old tooth brush and shop towel will do the trick.
At 113000 miles another maintenance issue if not done previously would be to replace the spark plugs, distributor cap and rotor and inspect the spark plug wires.
Reply back if you have more questions.
20 yrs Experience; GM factory Training ASE Master Certified with L1 advanced engine diagnostics
I replaced the fuel pump and filter 2 years ago.... I really hope that it is not the pump. I am going to change the filter as it is a cheap and easy thing to do. Also I will check the fuel pressure as well, is that the pressure (55-60) right at the throttle body?
Yes that is the pressure at the fuel test port at the engine.
Having the same issue again. New filter. Pressure is at 55 through the RPM range. Falls flat on it's face when I stomp on it. Is there a return line that can be restricted to see if it is a pressure problem?