Question2 weeks ago, my car idled badly, like a vapor lock, or too much or not enough fuel. I let it sit 1/2 hour and it started right up. Since then, it will sometimes hesitate (after the enginge is warm) when pulling into traffic. Today I had it towed, because it did the same thing in traffic. I have about 5,000 miles on new fuel filter pcv valve, wires, belts, battery etc. Is this a fuel pump issue?
AnswerCan't tell without connecting a fuel pressure tester, and reading it during the problem.
Even a new EGR valve can close on a piece of carbon, and act like a large vacuum leak.
Throttle position sensor can cause a hesitation during acceleration, when warm, but it isn't used when the engine is cold, so there is a possibility.
Mass airflow is another. Read this article,(Ford, but they work the same, and this is a good article). http://www.fordscorpio.co.uk/cleanmaf.htm
Van
