I have a strange problem that has been plaguing me for a couple years now. This problem seems to be tied to when the weather is it's warmest. (temps in the mid-high 90s)

I can start my truck without issue if it has been sitting for more than a couple hours. After the truck has been running and is up to operating temperature, if I shut it down, it acts like it can't get enough starting power out of the battery, It will run down within 5 seconds and ultimately will not start. I either have to get a jump or push start. After getting started again the truck runs fine and without any issues, and will restart on it's own if left to sit long enough after being shut down.

I have replaced the battery twice(bad cell both times which really makes troubleshooting difficult, the battery is maintenance free), had the alternator bench tested, replaced battery cables and cleaned all the cable connections to the frame/motor. My multimeter shows 13.8 across the terminals when idling, and during driving the battery gauge never drops.

I did convert to an electric cooling fan (13" autozone kit) aside from that, the truck is bone stock. I want to suspect the electric fan, but even during the cooler months I run the AC which keeps fan running all the time anyway and I don't have trouble.

I'm at a loss as to what else to look for and have spent many hours searching for similar problems to no avail. So if anybody has some advice I'd be happy to hear it.

 

That sounds very strange indeed. Maybe check the ignition relay? It might be on the way out.

 

I'll certainly test it when I get home; but I'm curious how that could contribute to what for all intents and purposes is the battery dying when I try to start a hot truck?

 

I had an old Chevy that did this it had an after market distribution and the wires would get corroded and I would have to move them around to get a better connection you could check that maybe?

 

Yeah I tried jiggling the battery cables, replacing them and cleaning their connections.

 

Doing some reading around the net I've come across the theory that my 19 year old starter is probably just at the end of it's life and is experiencing heat soak issues. By extension, I figure that when this is occurring, it's pulling down a larger amount of current from the battery and may have been the contributing cause to the untimely failures of my my replaced batteries. (3 batteries in 2 years is extremely poor luck otherwise)

Does this sound reasonable/valid to you folks?

 

yes it could be the starter causing excessive drain but check the + power cable to the starter for defects and the ground lead off the starter i had a subaru with your same problem and it was just the old + power cable

 

my vote is heat soaked starter...