I changed the engine in my 97 ford f150 4.2 to a 4.2 from a 2001 ford van. I have replaced the starter 3 times. Each time its starts one time and then kills the starter. I have changed the fly wheel after the 2nd one because it messed the teeth up. Please help i am ready to give up.

 

It sounds as if the starter is staying engaged, even after the truck is running. Find your starter relay, place your finger on the relay, have someone attempt to start the truck. You need to feel and listen for the contacts to engage, as it will make a click sound once engaged. If you do not feel or hear the click, and the relay becomes hot rather quickly, you have a faulty starter relay. Swap it with a known good relay (i.e. horn, lights, a/c, etc.) If your starter relay contacts are stuck in the closed position, it will constantly send power to the starter once you attempt to crank the truck. This relay only sends power when your attempting to start. Once you have swapped relays, start the vehicle, shut it down, and start it again. If this corrects the issue, a starter relay will cost you about $10-$20 at the local parts house.

However, if that does not fix the concern, you need to do the same test as previously stated with the starter solenoid, as it works the same as the interior relay. You will need to purchase a new relay for testing, as this is the only solenoid of this style on the truck. If the internals are stuck in the closed position, it too will constantly send power to the starter. This part will also cost you about $10-$20 at the local parts house.

Best Of Luck