i got a 96 civic wit a 95 ls in it. when i turn it on my fuel pressure goes up to 65 psi. so far i changed the injectors, fuel pump, the regulator 4 times, fuel filter, cleaned out return line changed ecu, throttle body, this is the third motor i put im the first one a thief got to and the second and third im havein this problem wit. if any body has suggestion or an idea whet else to change let me know. thanks

 

what fuel pressure gauge are you using? looks like you tried almost everything. what about the fuel rail or even the fuel gauge you used?

 

heres some options:

your gauge is junk
your return is cloged
you have a high pressure fuel pump installed
your pressure regulator is junk (or needs adjusted if it's aftermarket)

 

factory pump, tryed 2 gauges, and 3 or four regultor even an aftermarket adjustable one, it will pressure up but not down