I have been having trouble with my car (1991 camaro 5.7 TPI) losing fuel pump voltage. Sometimes when I am driving the fuel pump voltages just drops to zero. I guess it must be grounding out or something. It's completely unpredictable, sometimes I can drive the car fine and it maintains voltage, other times I will be driving for 5 minutes or 30 minutes and I just shuts off. When it happens I just leave the ignition on and after 10-15 minutes sometimes less the fuel pump kicks back on and I have fuel pressure again. I replaced the relay but I still did it, any ideas on where to start looking to fix it?

 

Get to the fuse by the battery in the fenderwell - remove fuse. Take the connector off the Oil Pressure Sending Unit (OPSU). There are 3 wires, 1 is smaller than the other 2. Take a paperclip, bend to fit in the connector, and jump the 2 larger wires in the wiring connector, then wrap it in electrical tape to keep it from touchng anything, and tuck whee it won't get lost/burnt. Replace fuse at battery.

This will make the fuel pump run ALWAYS as long as that fuse by the battery is in place. ALSO - you will not have any oil pressure readings on your guage.

See if that solves the issue. Run it like this for the day, removing the fuse at the battery when you are not driving. If that solves the problem, you need a new OPSU.

 

If the paperclip solves the problem, he's got more trouble than just the OPSU because the relay is supposed to feed the fuel pump when the engine is running.

visionpb16, where did you measure the voltage and what kind of voltmeter did you use? How fast did the voltage drop, was it immediate?

What is the fuel pressure when the pump is running good?

Lou

 

I checked the voltage 2 different ways, 1. I'm running the EBL flash in the car and it tells me my fuel pump voltage when I have my laptop hooked up to it, so the reading comes from whatever the cars computer is reading. 2. With a DMM (digital multi-meter) under dash on the drivers side where you would plug in a scanner or something. The voltage drops to zero within a few seconds with no warning. I have a fuel pressure gauge in the car and when its at idle and its running good it runs at 43-44 psi (fuel pump voltage runs around 13.5 V). When it dies it drops to 5 or 6 psi, another problem that happens when it dies is when I do finally get it started up again is the fuel pressure doesn't always come all the way back up to 43 or 44 psi, it stays around 38-40 psi causing the car to run lean and I bet the voltage is slightly lower too I haven't really looked at the exact voltage once I have gotten it started back up.