Petern

Truck is a 2wd 1991 f150 with a 5.0 and automatic trans with dual gas tanks with 140,000 miles.


Having a problem that seems like a bad ground, getting no spark and fuel pump isn't priming. But then it starts after consecutive tries. checked fuses and all the grounds i have ever messed with. any ideas?

here's the story for those who care

any info would be greatly appreciated because i'm out of ideas sorry i'm confusing


I recently Purchased a 91 f150 with a 5.0
I noticed the idle was high and did a vaccum check with a smoke machine and the upper intake manifold was leaking pretty good, so i decided to replace the upper and lower intake manifold gaskets, and the valve cover gaskets.

Everything went smooth and it came back together and fired right up. So I drove to the desert and everything was fine on the 120 mile journey. While cruising in a sand wash the truck shuts off.

Checked the ignition coil for spark and was not getting any, tried a new coil and same thing, and I didn't hear the fuel pump priming, towed it back to the road called a truck tried to start it one last time and it fired right up so i drove it home.

joefriday

The no spark issue almost sounds like a bad TFI. It shouldn't affect your fuel pump though. The TFI is still mounted on the distributor on your 91, correct? There, it heat-soaks on the distributor, and cuts out when too hot. Once cooled down, it fires up like no problem. I'd at least check the TFI. Remove it and clean off the old dielectric grease. Replace it with some thermal grease made for a computer's CPU such as this:
http://www.newegg.com/Product/Produc...-008-_-Product
It will keep maximize the heat transfer from the TFI to the Distributor, keeping it cool enough to maintain operation.

Other possibility could be a bad ignition switch, maybe a bad or poorly grounded ECM.

ymeski56

http://www.fordfuelinjection.com/?p=25 Or a PIP sensor (Stator). Do a KOEO (Key on/ engine off) error code scan at the least, & a KOER error code when it's running. Take the TFI off & have it tested. If the injectors aren't triggered, one might assume the fuel pump isn't running. The stator and TFI both share the same grounds and power circuits, when one fails the other might be bad as well.

Petern

Thanks for the advise ill check those out tomorrow and let you guys know. And where would I find the ecm ground? If im not mistaken the ecm is mounted on the driverside under the hood on the firewall?

joefriday

Good call on the PIP.

ymeski56

More likely somewhere on the way to the ECM, than at the ECM connector. As I mentioned, the stator and TFI both share the same grounds and power circuits.
It's difficult to tell the difference between the two as far as symptoms. The TFI will rat itself out when bench checked & the PIP, with error code scans. If your TFI is Distrib. mounted, you'll be sorry very soon, if you just deal w/ one at a time instead of just doing them both. But you can try it. I love it when somebody beats the odds. Most of this info's on the link!

ymeski56

You forgot about the PIP? It's not really an "in your face" kinda part.

Petern

Please forgive my ignorance, from what I understand the pip(stator) censor is mounted in the distributor, and the tfi is also mounted on the distributor?

ymeski56

Yep & yep. Until they realized the TFI faired better mounted remotely on the drivers side fender-well. Not sure what year it was, but they're one place or the other.

Petern

sounds good thanks for the advice ill give you guys an update with what happens.