Okay, I was driving my car and it almost died 3 times and then it die. I check for spark "Good" then I didnt have any fuel pressure so I assumed the fuel pump. I checked the voltage to the fuel pump right after I turn the key, I got nothing so no prime. I checked the relay I never heard it click. I went and got another relay put it and still nothing. I came back home and looked it up and the green/white wire was the one coming from the ECU to the relay to click the relay. Well, I jumped the orange to the green/white wire and it clicked and I could hear the fuel pump running. I jumped the relay and drove it home real quick. After I got home I check the voltage right after the ECU "green/white wire" and was getting .5v with the car running or with the 2 second prime. Do I need a new ECU? I jumped the fuel pump relay to the ignition so I can drive until I can buy a new ECU.

this would be on a 1989 camaro 2.8

 

Regardless of any relay/ECM problems pump should run from the fuel pump oil pressure switch ( assume it has one like the V8 EFI engines do )
That supplies power direct to the pump as soon as engine oil pressure goes over 4 psi and does so until engine is turned off.

Also allows engine to start if you have relay problems like you say you have ( with longer cranking to build up oil pressure )

Check your circuit diagram for the wire out of switch to pump and see if you have 12V on it with engine running

 

Yeah, I checked that switch I haven't had that oil pressure switch hooked up in forever. It will run with just the switch for about 10 secs then it will die. I need a new switch, but the car was running fine before even when the switch wasn't hook it. A mechanic that put in another motor broke the clip so it doesn't stay in very well.

 

Not sure it solves the issue, but did you check the fuse that is located between the battery and the fender?

 

Yep its good. I think the ECU got burnt out on the fuel pump signal relay green/white wire. It only 85 for a new ecu, probably order one here in a few days.

 

Did the ecu fix the problem?

 

Yep, the fuel pump is now wired the right way and working, and I also bought a new oil pressure switch.

 

Im having a siimilar problem. I can crank the motor over but get no fuel. I dont even hear the fuel pump prime. I dont want to buy the part just to try and see IF it fixes the issue. Is there any way to test the oil pressure switch? Ive rread something about there is supposed to be 12v coming from one of the wires to the switch to trigger the FP relay. if so which wire?

 

You need to check and see if you got power to the orange wire going to the oil pressure switch. The tan/white from the oil pressure switch goes to the fuel pump. That is how you check the oil pressure switch.

There a dark green/white wire that comes out of the ECU on the smaller connector. It goes to the fuel pump relay that kicks it on for 2 seconds for the prime. I guess when the ecu knows your cars on it will continue 12v to the relay, and will run the fuel pump. The tan/white wire from the fuel pump relays goes to the fuel pump, so it will make it run.

The fuel pressure switch gets power from the orange wire that comes from a fuse over on the passenger side, if that fuse isn't blown then check for power *orange wire* at the connector on the oil pressure switch. If you got power there maybe a bad oil pressure switch. The tan/white wire coming out of the oil pressure switch *ties* with the tan/white wire from the fuel pump relay. so if the fuel pump relay fails then the oil pressure switch will run the fuel pump. and it they both fail then ur screwed like me and you

but here a quick check to see if your fuel pump works or if you got a short in the tan/white wire going to the fuel pump. Turn the ignition on and get a short 4" wire and connect the orange wire to the green/white wire at the fuel pump relay, you can do this at the connector. You should hear a click and hear your fuel pump running. The orange wire is hook up to your ignition, so you can drive your car like this. I hope this helps

 

Not on 90+ , wire to pump is gray from both

See

http://www.austinthirdgen.org/mkport...ine_wiring.gif

 

My problem is constant power to the fuel pump it stays on with the car off and key out only way it shuts off is pulling the fuse or dis con battery...i tested the wires orange and tan/wht
Hve constant power so im guessing the tan wire is grounded or w.e. ??? Ive changed relays ive changed both sensors oil pressure switch and oil gauge

 

Bad oil pressure sending unit - driver side block just above oil filter - it can go bad and make pump run always

 

watching since I have a similar issue