High RPM Problems

[1Bad96]

I have a 96 GT with a 2000 PI motor. I swapped it out about a year ago. Recently when i roll on the throttle it will start missing a little, around 4500 RPM. Or if i drop the clutch from a stop it misses a little sooner. I figured it was either electrical or fuel. I replaced my coils which weren't even a year old along with my wires, plugs, fuel filter and im still having the problem. The car has an aftermarket fuel pump due to a previous nitrous system. I hooked up a fuel pressure gauge and taped it to my windshield and drove it to see what my fuel pressure was doing. At key on its inbetween 25-30 psi. and if i let it sit with the key on for about 5 minutes sometimes the pressure will drop to around 20 psi. When motor is running its around 28-30 psi. I looked up what it should be at, and it says at key on i should be 35-45 psi. When running it says i should be at 30-40psi. My question is could the low psi. be the reason its starting to miss up top? Thanks any input would be nice

PS. Stock injectors and stock regulator

 

[squares98]

I can almost bet it's that aftermarket pump giving you problems, what brand is it? The Cobra(190lph?) pump is a good upgrade if you need a new pump

 

[Mike97gt]

could be the pump, presure regulator or a injector sticking open slightly. if it was a injector it would run AWFULL and have a constant misfire. yuo would also have a crankcase full of fuel.

most of the time when a regultor goes the presure jumps up.

this leaves us to the pump, make sure it's getting over 12 volts. if it is then replace the pump.

 

[cooter_11]

Maybe try a fuel filter?

 

[1Bad96]

im gonna try the pump and see.....seeing how im gonna be running a supercharger down the road i think im gonna go with one capable of working with a blower. thanks for the input