EFI fuel pump not getting 12v with key on

[Labbster]

I have been having fuel pump issues as its a 1986 donor. Works for a while then when its really hot outside the engine dies. IF i wait 15 min, she will start again.

So, I just replaced the pump and ran all new lines and cleaned up the underside and now she won't start.

Normally with "key on" i hear the click and the pump runs a few seconds. Now I hear the click but no pump. So here is what I have done:

1) I get 12 volts when I ground the test port and pump comes on and circulates fuel. I did this to prime the system after putting in the new lines. also have about 40 lbs of pressure when doing this

2) The pump only gets 2.67 volts with key on and when trying to start and won't come on.

I have Ryan's harness and mustang efi

Help is greatly appreciated!!!!

 

[garberz]

The ECU provides the ground for the fuel pump circuit. When you ground the test port, it's working properly. I'd say you have an issue with the ECU itself.

Mark

 

[Labbster]

that's what I was afraid of!!!!!! Just walked in the door from attempting to run codes and my coder thing shows it has connected to the computer, but it is not running a self test... was gonna try to run codes with a light when I get back from church. Bummer!!!!

 

[ScanmanSteven]

I had a similar problem until a changed computers. But here's a work around. I ran a 12V lead to a lighted rocker/toggle switch. Flip the switch "on" before you start to prime the system and just start and run it. When you get to your destination just flip the switch off. As long as you you have a return fuel system, no problem. It's possible to fix the computer, it's probably some capacitors. I didn't fix mine but google it or send it to EFIGuy on here. Good luck.

 

[Labbster]

I finally ran codes through the warning light and among the smog stuff was a 87. My book states it is "fuel pump relay failure". How do I find the relay and how do I test it?

 

[garberz]

The fuel pump relay is one of the four relays on the RJM harness. Look at the power wire for the fuel pump, I thought it was pink, then look at the pin 87 on each relay socket and look for the matching wire. It may be easier to find the circuit with an Ohm meter. Pin 87 on the relay socket is the power out to that device. To test the relay, once you find it. Put 12v. to pin 86, and ground pin 85. You should hear a click, measure continuity between pin 30 and pin 87.

Mark

 

[EFI Guy]

The fuel pump issue sounds like a bad relay or poor connection at the relay or the connector for the inertia switch.

Failing to pull codes can be a bad computer. Try Applying ground to the STI and see if it will self-test that way. It also wouldn't hurt to crack the computer open and have a look...

[youtube]-O7FUoQzTB4[/youtube]

 

[garberz]

The power wire from the relay to the fuel pump is 14g. pink wire and is marked "INERTIA>F-P"

Mark

 

[chuck]

Are you sure the ECU and tank/pump have good grds?

 

[Labbster]

EFI GUY i watched your video and took my computer apart. The 10 63v 105 temp looks like it may be my problem. It doesn't look corroded like your video but it does look a bit burnt. it also smells like electric burn. I can put in the new capacitors tomorrow, but am wondering if you suggest more since it looks burnt...

 

[Labbster]

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[ransil]

Change the caps clean up the area and try it.

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[Labbster]

She runs!!!!! Thank you all for your help! I never thought I would be soldering circuit boards but....

 

[Labbster]

What are the odds of the computer going at the EXACT same time we replaced the fuel pump and high pressure lines? We pulled the Bronco in the garage and shut it off. I crawled under the bronco and told my son to fire it up one more time because I wanted to check a spot that was barely leaking. When he did, the pump never shut down it just kept running until he turned the key off...anyway, thank you all!