My 87' 302 has a hard time cranking when it gets hot it will turn over but it slowly turns over slower and slower. Things ive replaced:
New battery
New Alternator
New starter
NEw starter solenoid
NEw battery terminals and wires
Ive done all i know to do!!! Im stumped.... Please help

 

Do a amp draw test on the starter. AutoZone or any good shop can do it for you free. Do it when the truck is warm. Don't let them just tell you good or bad ask for the actual reading. Could be a bad starter. Also check and clean all wire connections. Measure resistance at the ground and power wires.

 

Double the positive cable. Helped mine a lot.

 

Ive put three brand new starters in it. Could be that they're getting real hot. Heat rap???. Also will a Regular volt meter check resistance?

 

Sean what do you mean by doubling positive cable?? :/

 

Use two positive cables.

Attachment 118692

 

As long as it reads ohms of resistance. Most meters do.

 

Thanks guys! I took it up to O'reillys and got a amp draw test done on it! The starter was pulling 350 amps!!!! WOW!!! Im going to buy a gear reduction from summit! Im done with these cheapos!!!!

 

Ok. Here's an update. I put a protorque gear reduction starter on it. Every single wire is new on the battery and solenoid and starter. The solenoid is new. The battery is 1,000 CA. And is tested at 100% charged and 13 volts. When the truck gets hot it cranks, but very slow and doesnt want to start....Im stumped.

 

Check and update all body and engine grounds