i have an 81 F150 with a 302, in the past 4 or 5 months i have done an engine swap, it was fine until i did a cab swap, once i put the new cab on it woulndt start and stay running, it would try to fire and then immediatly shut off, when i turn the key it would try to fire, i let off the key it dies, i put a new ignition switch on it, the actual switch not the key switch, and its still doing it, i've checked the timing, checked for vacume leaks, and i know i've got power out of the coil....if anybody has any idea let me know.....please....

thanks,
Aaron Younger

 

Sounds like you don't have both power wires to the Duraspark hooked up correctly. Most older ignitions have 2 power wires, 1 for the run position, and 1 for the start position. If you only have power to the start position, it will die when you let off the key. At least that is my knowledge. Did you use the original harness and column or the one off the donor pickup?

just a thought.

kenny

 

well the deal is i bout a truck and wrecked it...so i bought anouther truck and put my motor and trans in it and when i did the cab swap, thats all it did, that why i thought of the switch, to my knowledge i hooked everthing back up the same way as i took it off, i tried moving some wires on the solenoid yesterday but it didnt help...

 

I think mudgepondexpress is on the right track on this one. Here's an idea to check this theory. You'll need a second pair of hands. Pull the little "Start" wire off of the solenoid. Make damn sure your in park or neutral. You will be bypassing all the safety switches. Have someone hold the key in the "crank" position. With the solenoid wire disconnected, it should not crank, but if mudgepondexpress is correct you will have power to the ignition system. Now, jump the battery terminal on the solenoid to the terminal you pulled the "start" wire off of on the solenoid with a screw driver. This will crank the starter. Once it starts, remove the screw driver. As long as your helper holds the key all the way forward, the truck should stay running. By the way, the two power wires on the Duraspark are the red and white wires. One should be hot only durring cranking, the other should be hot in the run position. I forget which is which. Oh yeah, the reason for 2 wires is during cranking, the Duraspark retards the timing for easier starting. So, while the truck may run like this, it won't run well. You need power to the correct wire at the correct time for proper operation.