Ford problems.....91 5.0 f150

FlatlandFSJ · Apr 7, 2016

This thing has whooped me pretty good. It's my dads work truck, he brought it by the other week and it was running kinda rough. Couple days ago it just wouldn't start anymore, new relays for the ecm/fuel pump/brain on the dist/coil/blah blah blah. Still nothing. Cranks over, no spark no fuel. Dropped the tank, pump checked out good.

Tried to pull the codes (jumper wire/dash light deal) and it wouldn't give me anything. Tossed a reman computer in it and it fired right up, ran a little rough but smoothed right out after about 10-15 mins. Rode it around the block a few times, ran great, better then it ever has since he bought it. Shut it off, went to fire it back up the next morning to bring it over to him and nothing. Same thing it was doing when it died a few days ago.

I've tested all the relays, and from what I can figure out...The computer is not internally grounding the fuel pump relay, I jumped it at the connector and the pump comes on and runs fine, so the wiring to the pump should be fine.

I went over the wiring between the relays and the computer and it all looks good, no bare spots that could short out.

I'm lost at this point, any of you ford guys seen this kinda junk before?

TBItoy · Apr 7, 2016

Re:

Check the fuel pump inertia safety switch

I think it's on the firewall under the dash or kick panel on those trucks

toreadorranger · Apr 7, 2016

Re:

TBItoy said:
Check the fuel pump inertia safety switch

I think it's on the firewall under the dash or kick panel on those trucks

I think they are under the dash on the passenger side near the glove box.

gottagofast · Apr 7, 2016

Yup... Not uncommon to spend $$$$ trying to fix a ford only to solve the problem by pushing a button :flipgotcha:

ford

84mallcrawl · Apr 7, 2016

check your O2 sensor wiring.

pholmann · Apr 7, 2016

Warranty that ecm. Also don't forget about the tps. They will play hell with em. Coolant temp will kill a ford too.

FlatlandFSJ · Apr 7, 2016

The new reman is already on the way, swapping for it this afternoon. It's not the inertia switch, it's the first thing I checked when it wouldn't crank up.

The check engine light doesn't come on when you turn the key, and it doesn't want to spit out any codes. I'm guessing it killed the reman computer, which is making me think wiring somewhere.

pholmann · Apr 7, 2016

Junk ass aftermarket reman parts. Don't overthink it.

44BRAND · Apr 8, 2016

pholmann said:
Junk ass aftermarket reman parts. Don't overthink it.

Most likely this^^^^^ However make sure to check all your grounds really good, old cars get corrosion on the grounds and may look ok but aren't. Especially check the grounds to the ecm and the main body ground( small wire from battery to body). Good luck and hope you get her going.

FlatlandFSJ · Apr 8, 2016

It was a combination of a shitty reman computer and a bad icm on the dist. Computer took out the icm, or vice versa I guess. New computer, good icm (had them test it before I left the store) and it fired right off and is running good. I'm using it for errands today and it hasn't died on me yet.

I cleaned all the grounds I could before I got the first computer, apparently it's a BIG problem on fords in those years.