fuel pump relay?

[fatt_owl2.9]

for the almost 2 years I've had my truck, it's had an intermittent problem with the frame rail pump not engaging every time I turned the key. It would come and go, sometimes be really bad, and then sometimes disappear for quite a while. Finally a couple months ago I was having some other work done on the truck, and the mechanic (who is really good, and I trust) couldn't get her started at all, and he recommended we replace the pump, which I did. I haven't had any problems with it starting since, but every now and then it will just die in the middle of traffic, but usually starts right back up with no trouble.

well, last night it died in traffic, and no matter what I did, would not start again. That fuel pump will not cycle no matter what. Towed it home, went out this morning, and the pump still won't come on. Is the FP relay the next thing I should be replacing? I'm gonna scream if it's something like the ECU. I'd also wanna replace the inertia switch, but the general consensus seems to be that those seldom to never go bad. Also, where is the fuel pump relay located? Thanks in advance for any advice guys, have a good one

 

[79F1504X400]

Fuel pump relay should be next to EEC relay on pass. side. Fuel pump relay has green base, EEC relay has brown. Check condition of wires going to fuel pump. Mine had a small break in the wire. It appeared fine on the outside, but was broke internally. Also check the ground for FPR which was problem for me. I found it was located on the neg. terminal for the battery. It was corroded inside the connector so again....outward appearance was fine, pull it apart and viola....no connection. As its been mentioned many times on these boards.....Check the grounds!! Oh so true. Good Luck and report back with your findings.

 

[Psychopete]

Could also be computer relay since the computer controls the fuel pump. Probably going to have to try and arbitrarily replace them, or test them.

There's a ground on the diagnostic connector that will over ride the computer's fuel pump control (it causes it to run constantly with the key on run). There is a good pic of this in this 2.9L forum showing which terminal, but can't remember who posted it. Also have found it by searching the right terms on images.google.com.

Pulling codes, regardless if you're expecting anything, is a easy way to tell if your computer is powering up and sane. Might start here to make sure the computer is turning on.

 

[fatt_owl2.9]

excellent info so far guys, thanks a lot. I'm totally retarded when it comes to electrical. Dumb question, but what would be the best way of going about getting scanned for fault codes? thanks again.

 

[Psychopete]

See here:
http://www.muscularmustangs.com/test1.php

I've found better, but this is a good outline. They talk about the separator pulse a lot, all it is a blink between the key on engine off test, and the store memory code output. Basically there are two tests that the computer will run through with the key on and engine off, and the blink is an indication that it's moving on.

There's also an EEC-IV diagnostic section on this site as well in the tech library.