BigChulando

So, I have read through MANY threads on the issue, so know all about jumping Fp and +B, and that has gotten me by a few times. The problem is intermittent about 4 times in the last few months the truck (91 22re) would not start. A quick bypass and she fired right up with no problems for weeks.

Now, it happened again, but this time saw no evident spark when jumping the two, indicating no power. Assuming the EFI relay was bad got a replacement, only to find out at 10pm last night they must have given me one for the wrong year as id did not fit.

So, I found on here that some people have bypassed the EFI relay by giving juice directly to Fp or +B. I tried both and still could not hear the pump kicking on (with ignition ON). What am I doing wrong here, what is the proper method for bypassing the EFI relay?

On a side note last night when I was about to give up and try to find a different way to get to work in the morning. I had it jumperd with no power still, was frusterated and slammed the drivers door shut, and voala must have jarred something and the pump turned on. Then she fired right up...

scope103

The proper way is to not even try.

If the EFI relay is out you won't have any power to the ECM, so nothing will work. You might be thinking of the Circuit Opening Relay. If you get into an accident where you break a fuel line, with the COR bypassed the fuel pump will just keep spraying fuel. You don't want that.

But the FP connector goes straight to the fuel pump, so if jumping it to B+ doesn't work you either have a broken connection to the pump, or no B+. If you don't have B+, you have an open on the EFI relay side.

Get a multimeter http://www.harborfreight.com/7-funct...ter-98025.html and figure it out. Otherwise, you're just throwing parts at it.

BigChulando

I see your point about the danger of running with the COR bypassed. People may want to think twice about doing this trick then (which is referenced quite a bit around here):
http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

Since I wasn't getting anything jumping Fp to +B, I connected each straight to the battery (bypassing the EFI relay), with nothing still. So I see what you mean about a bad connection at the pump. That will be my next check. Thanks

I have the HF multimeter you linked to, but the display is pretty much shot. I will be getting another soon.

BigChulando

Found the problem. Looks like you were right Scope. The PO apparently had a nice thumpin system, as I've found all kinds of audio wires throughout the truck. Well, the dumba$$ chopped up the wire harness near the passenger door for some reason. I found several wires including the 3 that go back to the fuel pump cut and just twisted back together. No solder, no tape, nothing, just the bare twisted wires. It's a miracle I've made it this long...

Thanks for your help

scope103

Even 4crawler is pretty clear about why this is dangerous. Read the entire paragraph starting with "So running with the check jumper installed is not ideal as it defeats a safety feature built into that system."

The good news, of course, is that your careful diagnostic skills tracked it down. DO replace your multimeter; you'll find plenty of other uses for it.