I just installed a 5.3ltr 4L60E into a 72' El Camino....I used an external Walboro Fuel pump and the Corvette fuel filter regulator...The first time I switched ignition ON fuel pressure went to 58 psi....So everything was good until I fired up the motor and the fuel pressure shot up to 100psi and didn't go down! I changed Fuel filter regulator, checked for any kinks or sharp bends in fuel line and dropped fuel tank to make sure return line wasn't clogged or something but I didn't find anything wrong!!! Fired motor up again and pressure shot up to 100psi again...WTF!!!
I'm using 3/8" fuel line for return and pressure side...Any Ideas???