ok first my fuel pump was out all the way, not turn on at all. Replaced fuel pump, fuel sifter, fuel pulsator, fuel filter and fuel relay. Car started up fine and ran great for a few days, and then it started to get really hard to start. I have to crank it for sometimes 5 to 10 seconds, then when it does fire it will barely want to fire, then it will idle ok. When I try to accelerate it bogs down and then goes.

I tested it with a fuel gauge, and I noticed that it moves up very fast around 35psi for the few seconds of the priming then right when it is done priming it drops down to 0psi! (I did read that its supposed to drop but only a few psi. I turned the ignition and it starts to come back up again and it takes for ever to start and then it starts. Another weird thing it is only at like 30-35 psi, shouldn't it be like at 45?

I hope that is enough information for someone to help me, if not ask me more. I am thinking it could be the fuel pressure regulator?, oh yea my car is 89 camaro 5.7tpi iroc-z.

 

Stock fuel pressure should be around 43, when you check the pressure remove the vaccum line on the regulator to get a proper reading when running.

 

When I remove the vaccum line on the regulator it makes no difference at all.

 

At this point you need to troubleshoot the regulator, and supply line check valve (it's part of the pump.)