I am still having problems trying to figure this out... When i try to start my truck there is sparking by the starter solinoid on the side that the battery connects to. I go through solinoids like candy and if I continue to try to start it I turn the key off and it continues to try to run and the positive wire for the battery starts to smoke and fry to the solinoid. I can't figure out what wire is doing this or why am I going thru so many solinoids... Nobody answered my last post and just wondering if anyone can help...

 

Maybe your starter is drawing too much current and frying the solenoids contacts. It almost sounds like the solenoid contacts weld themselves so that the starter continues to turn even after you shut off the truck.

Without any diagnostics to base a decision on I would guess you have a starter going bad.

 

Normally I would suggest making sure the starter relay is well grounded, but if it's actually sparking, that sounds to me like the cable going to the starter is grounded someplace. Check both.

 

Make sure you are using a motorcraft solenoid, anything off brand from autozone or similiar are junk. I went through 3 in just as many months until I got a Motorcraft. They either stayed engaged or would not engage. If that is not it try as suggested and check the starter.