Hi y'all,

I'm having an issue with my 1991 7.3 IDI that i can't seem to figure out.

I recently was replacing my theromostat, and when i finished and went to start up the truck it wasn't turning over. After doing some diagnostics i determined that the starter relay (some people call this the fender solenoid) had gone out. I was surprised because i has just replaced it in may, when it had gotten stuck on and took my out starter with it, and now it had some how died while the truck was just sitting in the shop.

I replaced it but the truck still wasn't turning over. I borrowed the starter relay out of a friends 7.3 IDI and the truck started right up, so i thought i had just gotten multiple bunk relays, but after one drive the relay was dead, and the truck wasn't turning over again. It appears something is killing the relay but i can't figure out what. Hoping y'all will have some ideas.

I'm getting 12 volts from the ignition to the small terminal at the top when i turn the key, and the truck turns over no problem when i bridge the two large posts on the relay. I have 0 ohms resistance on the wire from the relay to the starter. I haven't found any corrosion anywhere, and both my batteries are in good shape.
Anyone have any ideas about what i might have going on here?
Thanks. This forum has been big help in me working on my truck and i really appreciate it.

 

The relay is completely oversized for it's job. This relay is designed to transfer 350 amps to the starter of a big block ford gas engine.The diesel engines have a solenoid built into the starter, so the fender mounter starter relay only has to transmit about 10 amps to the starter solenoid. I'm guessing your problem is either the trigger wire that may be broken inside the insulation, or a bad ground between the fender and the relay. The relay grounds itself through the bolts. Next time this happens, unbolt the relay and bolt it back on. I'm guessing it'll work after that.

 

new no longer means good.
i have replaced up to ten chinesium starter relays at a time to find a good one.
i no longer buy parts store junk. i now only buy stancor relays. yes they cost $57, but i never have to buy another one.

 

the post will turn if you tighten it too tight and the the point thats raised internally gets burnt out

 

Also verify that your press on trigger wire connection is tight. I've had to "crimp" mine on several trucks with pliers so they made a good connection again.

If you can operate the solenoid with a screwdriver crossing terminals you have a signal wire issue.