Expert: Tim hagan - 5/12/2009

Question
QUESTION: I have a 1995 Yukon that won't start after the truck has reached any kind of temp. If I let it cool down it will start without issue and run without a problem. I also experience the gas gauge needle moving up and down when accelerating or braking. This model is equipped with a 5.7 V8 with throttle body injection.

ANSWER: could be a failing fuel pump, when it will not start check the fuel pressure

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QUESTION: I have not checked the pressure but I do not see any fuel when I turn the engine over. However I am confused how the pump could be failing when it runs fine once started and the no start only happens when the truck as at op temps.
I appreciate your response.

Answer
because when you first start it the pump is cold, after you run it the pump builds heat which is cooled by fuel flowing through it, if its not pulling enough fuel or just barely enough then the pump has to work twice as hard and gets even hotter, once the truck is warmed and you shut it off, the pump needs to cool off again