I got a 1986 D150 5.2l with the lean burn system. I am having troubles trying to get it to run. It will fire when cranking, but when it starts when cranking letting off the key into the run position kills the spark . I heard there problems with the lean burn idk if that is the problem.

 

Check your ballast resistor/connections, Coil gets direct battery voltage during cranking and then goes through the resister in the run position.

 

That’s what I was thinking after looking online and doing searching, but I don’t think I have one. I think it’s part of the computer. I got two trucks so I know what it looks like, but I can’t find one on this truck

 

Get a wiring diagram of the truck and find the two wires coming from the ignition switch. One should be crank and the other one run, Resistor should be on the run. The diagram shows the resistor separate.