i have a 96 trans am, and just curious my car is cutting up and idleing rough...so i was just curious what a bad fuel pressure regulator would do? also my fuel pump was staying on longer than normal and had a loud whistle to it...what causes that?

 

the fuel pressure regulator can fail and let fuel into the vacuum line that controls it. that will cause unmetered fuel into the engine causing negative fuel trims. You can easily check for this by taking the vacuum line off the regulator and smelling it and looking if its wet. if it is, you need a new regulator.

The only thing a fuel pressure regulator does it raise pressure when there is little vacuum. So you can throw a fuel pressue gauage on it and rev the enginem the fuel pressure should go up. You can also pull off the vacuum line and it should go up also.



Idleing rough can be caused by many things. a stuck open EGR will cause a rough idle for sure. Also, if the MAF is not measuring the air right it can cause an extreme rich or lean condition and create drivibility concerns.