I'm at my wits end here and hoping you guys can help. i have a 1990 ford f-150 with the 4.9L inline V6 I love my truck would own no other kind then ford. but this one is killing my wallet. here is the problem my truck starts just fine runs good has a slight miss. but that's not the issue the issue is once it warms up to operating temp. and i shut it off it will not start again. i have to let it sit for an hour or two before it will start if i try to start it before it has cooled it will turn over and make a sound like ERRR ERRR but wont catch and when i turn the key back the motor jerks also there is a ground running from a plate on the firewall by the wiper motor that look's like it runs to either the bottom of the block or the transmission bell housing cover that heats to the point of smoking and being VERY hot it i hold the key over trying to start it for to long. I have replaced the started with a brand new one not remand. brand new starter solenoid battery cables, battery terminals. thermostat battery is tested good on 6 different tests same with the alt. PLEASE if someone can help me. I'm about to lose my mind. thank you ahead of time.

 

Hot wire means there is resistance. You have to find out where. I had a similar issue, I added a ground cable from the starter bolt to the engine block. Check all your grounds, not just the one on the battery.

 

First of all a 4.9 is NOT a V6, it is an inline 6.
Historically they have a hot re-start problem. This is due to the proximity of the fuel rail to the exhaust manifolds. It causes the fuel in the rail to vapor-lock.

Ford used to use a small ventilation fan which ducted air to the fuel rail. It would run after the engine was shut off to limit the vapor-lock tendency. in later years they just installed a heat shield to deflect the rising heat away from the fuel rail.

I don't know which was used in 1990. If yours has the fan, make certain that it is working properly. If it has the heat shield, make sure that it is in place. If it has neither, you may have found the problem.

 

To be honest there is no fan/heat shield on my truck nor has there been since i bought it. but is there any give away as to tell if it had/should have a fan/heat shield any where?

 

I have the same truck and I do not have a fan or I don't think a heat shield, but I have never had this problem.

 

This isn't a fuel problem - it's electrical, and the fault is most likely a loose ground at the block. Your (+) wire is simpler than this, but your ground is identical:

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All 4.9Ls have the heat shield (#71); only '87-89 have the fan.

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Make sure the ground wire connects to the frame near the pass side engine mount, and the block. Stock ground cable bolts to the lower starter mounting bolt. You stated that the engine kicks back if you let go of the key, this could be a timing issue. Check the ignition timing with the spout disconnected. It should be 10 degrees btdc. Good luck.

 

Some block grounds are at the R engine mount lower front bolt (#25 View D).