Fuel Pump Relay Problem

How to test a fuel pump relay.

Category:

Autos & Vehicles

Tags:

• GM
• oil pressure switch
• fuel pump relay
• relay testing
• no start
• fuel pump relay test
• computer power
• computer
• ground
• how to

[ScannerDanner]

@kenjackson1977 lol, or course you know I agree with that, but either way I will still help you

[kenjackson1977]

@ScannerDanner ok man i totally 100% appreciate it and your time. I will look tomorrow and trace the fusible link and see what i can find. Ill get back to you with results as you've been helpful as s.o.b to me. I have no clue haha but learning quickly from your shared knowledge i should donate or buy this book?

[ScannerDanner]

@kenjackson1977 If you have no power at the pump fuse then you have a fusible link problem. I believe these are attached to the starter battery post. Maybe you left one off when you did the tranny or you connected one to the wrong post. All fusible links must go to starter battery post. The post that has the positive battery cable.

[kenjackson1977]

@ScannerDanner its not priming when i turn key on....pour fuel in it will start....

[kenjackson1977]

@ScannerDanner i turn key on i dont even see power on at the fuse or pump relay on firewall when on the test light...yet pour fuel in and starts hmmmm im stumped buddy.

[kenjackson1977]

@ScannerDanner ok....i rebuilt the fuel pressure regulator... did not fix the problem. So took the clip off back of distrib. and put light on the box with purp/white white wire did it 3 times and nothing cycled nothing happened. I went to junk yard grabbed 35.00 computer...changed the prom to from old one to the junk yard one nothing happened....wants to start but isnt...pour fuel in throttle body and starts right up..still no pump kicking on...

[kenjackson1977]

@ScannerDanner ok,going to go do this test i will get back to u in few hours thanks a bunch.

[ScannerDanner]

@ScannerDanner BTW this is the kind of stuff that I teach in my book.

[ScannerDanner]

@ScannerDanner Another clue to this problem is when you first turn the key on you should still get a fuel pump "prime". This is the ECM turning the FP relay on for a second to bring fuel pressure up. After this "prime" the ECM will NOT turn the FP relay back on until it receives an RPM signal (on the purple-white ref. wire).

If you do not have a "prime" happening when you first tune key on, then we are barking up the wrong tree. I can still help you though.

[ScannerDanner]

@ScannerDanner If the FP relay turns on and the injectors fire you need to replace the ignition module. I know, I know, "but I have spark" is what you are thinking. Listen, these modules will fail in that it will still control the coil, but not send the reference pulse (0-5v square wave) on the purple-white wire to the ECM. Without this signal the ECM will not see an RPM signal and will not fire the injectors and will not run the pump.