Wont start

[Thomas Slain]

I just picked up an 86 f350 and I'm having problems. When I crank the engine it doesn't start like it's not getting spark until I release the key back to the run position. Then it tries to start. Any ideas?

 

[Fellro]

May well be the ignition control. The old DSII boxes were dual powered, 12 for start, 9volt for run. It is possible the one circuit has gone bad, which would be once you release, it switches back to the 9V circuit and tries to fire. The TFI module on the distributor was also not the most reliable thing either.