MY 81 F-150 will not start. Thought it was the starter and tried several..then tested it at autozone it passed. Put on a new solenoid and battery and even new ground wire, but nothing at all! What could it possibly be I reallly need to get it running asap as it is a dd. Thanks for any help

 

Have you verified that you have power to the solenoid, and that the solenoid is working?

 

Not full power

 

Are you thinking your positive cable is good? Do you have battery voltage at the solenoid?

 

I don't really understand because when we bench test the starter it goes full bore, then when it's on the pickup it just clunks

 

It sounds like you aren't getting enough voltage to the starter when its in the truck. Do you have a voltmeter to check voltage at the solenoid and the starter positive post when cranking?

Not my favorite way to do things, but you could use jumper cables to try get full voltage to the started bypassing the starter circuit in the truck. Be very careful if you do this as you end up in a dangerous position.

 

We have tried that but I think I will just get a new starter as this one as been remanufactured and those are usually junk.

 

It really sounds like you have too much resistance in the starter circuit.

I assume all battery connections are clean.

 

Yes I put on a new ground cable I think everything is hooked up properly, but prior to this the starter always took a few revolutions before it finally caught and wanted to start

 

I dont know if you knew this but in order for the starter to work you need two ground cables. Wire #1 needs to run from the negative battery post and bolt to the engine block, and wire #2 needs to go from the negative battery post to the fender that the selonoid is attached to. or you cound just run a cable from the engine block to the fender, it should work either way. If all you hear is a clunk when you try to start, im pretty sure that means that the selonoid is grounding properly, but the absence of the second ground wire is keeping the starter from grounding properly so it cant engage.
Same thing happened to my truck a while back.