Alright, cars been running like crap lately. I've changed everything in the electrical side thinking it was the culprit. It seemed to work okay but today went out to start it and it won't. It has been running lean lately so I wondered if it was fuel pump related. BTW, 86 305 TPI. I reached over to the TPS and flipped it--as if the throttle had turned it so I could trick the injectors into firing faster than they should, and the car ran great. I went out and bought a fuel pressure tester to prove my theory and sure enough I'm reading 18psi at the rails. Anyone know if the regulator could cause this or if it's the pump and relay. BTW, I replaced the filter two days ago.

 

Bobcat,

The cause can be the pump, the fuel pickup strainer, the pulsation damper, the regulator, low voltage to the pump )including a poor ground), the fuel filter, or a restricted line/hose.

And easy method to determine if the regulator is at fault is to reconnect your test gauge, pinch the fuel return line closed, and power the pump. If the pump will produce at least 48 PSIG with the regulator return line closed, the pump should be adequate.