Fuel Rail Pressure

[ajaciuk]

When I key my car to the on position after it has been sitting and fuel pressure has dropped off will I see instant pressure at the schraeder valve on the fuel rail if my relay is working correctly? It is a 86 305 TPI motor.

I think it might be my Fuel Pump Relay but my mechanic swears it is the fuel pump. If I hook up the fuel pressure gauge at the schraeder valve I get no pressure until I start cranking it over then it jumps to around 43 lbs.

It has been taking alot longer to start lately so he thinks the pump will gradually build up enough pressure then the regulator sends enough fuel to to start it but I think the oil pressure switch finally sees enough pressure then powers the pump to start the car.

Any input is appreciated

[MattODoom]

I think the oil pressure switch finally sees enough pressure then powers the pump to start the car.

You sir are 100% correct. When you turn the key to accessory you should hear a 2-3 sec fuel pump prime. If thats not happening your fuel pump relay is out. If the relay is out the oil pressure switch will still run the pump however it takes a few seconds of cranking for the motor to build pressure.

Change the relay out and go

PS. your mechanic is a retard stop going to him.

[klrlt1]

Id change the Fp and regulator and call it a day..

[ajaciuk]

I had to eat crow with my mechanic today. It was the fuel pump.

We checked and double checked all the easy fixes and they were all ok.

I just didn't want to spend $500 on it so I was looking for an easier fix.