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I just bought a 84 F150 4.9L MT 4x4 that has a problem that baffles me and my mechanic friends. With the key on and the engine off the coil fires the cylinder that the distributor rotor is pointed at over and over again non stop till the key is turned off. When you crank the engine all spark stops. I have replaced the ICM, coil, and starter relay. I have ran the test to the ICM and all voltages are with in specs. This all started after the battery terminals were cleaned. Ran fine into garage, removed battery cables neg first cleaned terminals, put cables back on neg last went to start the truck and this problem started. So the last time it ran was when I pulled it into the garage. It has to be something simple I did no major repair to it. I even checked to see if the pin on the distributor gear sheered but its tight as can be and the rotor turns while cranking. Please some one has ran across this before. I have never came across a pointless distributor firing when the key was just on and not running.