Wow!!!! Not sure where to start. Battery started draining over night and finally notice that the fuel pump has power even after shutting the truck off. Did some digging and replaced the fuel pump relay. The plug for the relay has at sometime gotten pretty hot. Unplugging the altenator makes no difference. Unplugging the ignition wires under the dash eliminates the problem. More reading threw threads and studying the manuel leads me to believe the eec may be bad or the ignition could be bad. The only other problem I can see is that after driving a while the truck will barely turn over but after it cools it will start right up (not sure if this is even related). Really want to find this elctrical problem and get it fixed so I can move on to the starting when hot problem.

The only other weird thing that might help is, this does not happen every time the truck is turned on if the battery has been disconnected. BUT after disconnecting the battery and cranking it several times it happens every time until the battery is disconected again. I am usually pretty dang good at fixing my old buddy but this one has kicked me in the rear. Any help would be greatly appreciated.

 

Sorry, should have added that I have a 1989 f150 with a 5.0 EFI, automatic, regular cab with only one fuel tank. The only aftermarket part anywhere in or on the truck is an aftermarket radio that I have had in the truck LONG before this problem began.

 

Does the engine stop running when you turn off the key?
Sounds like your EEC power relay is closed all the time and the wire from pin #22 of the computer is grounded going to the fuel pump relay coil and the self-test plug.