start problems on 1998 Chevrolet Metro

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Ok I got a two part question for anyone who can anwser them first i have a 98 metro and when the vehicle is warmed up, I get in to start it and it turns over but will not start I turn it off and continue to try it for a couple minutes before it will start I've replaced fuel pump, strainer, spark plugs, wires, distriputor cap, and rotor what else can i do? Second question is when i'm at high speeds on interstate whenever my foot slips off gas peddle I loose all power to the engine The car slowes down and after a few seconds it kicks back in any suggestions
(1) Answer
The two questions would be related to the fuel preasure regulator. If the regulator is bad you will not hold fuel preasure on the system when you shut it off. If its hot the unpreasurized fuel will vaporize in the rail so the engine won't get enough to crank. The regulator is also vacume controlled, when the throttle is released quickly the vacume to it will spike causing it to dump fuel preasure. A test gage on it and watched during driving will find the problem. The fuel preasure should run around 36 psi and vary about 10 psi under driving conditions.