The starter on my '89 F-150, st-6 starts the truck when cold, but after warm up and drive, it seems to lack power to turn over engine, I have to let it cool down for it to start again.. It sounds like worn out battery, but that is new and alt is fine. any suggestions? The solenoid on the fenderwall is newer also.

 

Cables.

 

Sounds like high starter current draw when hot.See if you have a local parts store neer you some will do a starter draw test for free.

 

I had the same issue on my '87. We put an insulating sleeve around the starter to help keep it cool. I also bought a Meangreen.

 

I'm dealing with the same problem, its cause of bad connections and starter. Same thing i got new solenoids, battery and alternator reads its working perfect. Drawing too much current and its getting hot killing the battery. Rebuilt mine twice, lasts about 3 months and does it again. Plus my cables are corroded and got cooked from the engine heat overtime. Doing all that tomorrow hopefully.

 

I re did my battery cables this summer- went with 2 gauge cables rather than the factory 4. I am quite pleased.