1987 F-150, 302 auto. Last year starter solenoid failed, resulting in starter spinning away after engine started. Replaced solenoid. Same problem. Replaced starter, ignition switch, solenoid. Same problem. Was told that a bad battery could cause solenoid to fail, sounded silly to me, but tested battery and it was bad. Replaced battery and solenoid and worked like champ. Yesterday, solenoid failed (starter wouldn't stop). Tested battery and it's good. Replaced solenoid and it worked once, then on second time starting up truck, same problem. Removing the wire from the start post doesn't make the starter stop, just banging on the solenoid will. Any ideas as to what is going on here???

 

Sounds like the starter is drawing to many amps. Put an amp gauge on the starter cable and see what it is drawing. A starter solenoid is only good for braking the current for so many amps going through it. If it has to brake more then that it can weld shut.

Note a low battery will also cause to many amps through the starter circuit. That is why they said a bad battery could cause it.

 

Thanks, subford, will try that tonite.

 

yep, drawing excessive amps (forget what the number was). So, question is, what caused this? Everything was fine yesterday morning. And, had similar issue last year. Seems odd to be an ongoing problem. Will replace starter and solenoid tomorrow.

 

i had this same problem on my mustang i replaced every part you did but the only thing that ever fixed it was going to Ford and getting a Motorcraft starter solenoid. I went thru 3 BWD starter solenoids all three lasted for about 2 months then i went to advance and got a GP sorenson and that lasted one start and something broke on the inside but right when i got the motorcraft one it has been working for 4 years now. either that or pull a factory one at a junkyard.

 

Well, a couple more solenoids and 1 starter later, same problem. I give up. I'm taking it in to the Ford dealer next week. I hate to do that, but I just don't have the time or patience.