M20J won't start and my mechanic is stumped

[PT20J]

1 hour ago, MisfitSELF said:

I’ve kept on digging and what I’ve managed to find is that my A3B6 may be properly configured with the jumper removed.  The Champion/Slick site isn’t really clear but my right Mag (different model number than my left mag) may not have the impulse coupler.

Lycoming shipped my A3B6 with Slick mags: 4372 (impulse coupling) on the left and 4370 (no impulse coupling) on the right. That is the condition that SHOULD have the strap installed as the purpose of the strap is to ground out the right mag so it doesn't operate during starting. Since the right mag doesn't have the impulse coupling, the spark will not be retarded during start and it will fire the plugs too early at the low cranking rpm without the strap. You only remove the strap if you have two impulse mags installed or if you have the dual mag on the A3B6D. Check with your A&P.

Skip

[RogueOne]

On 9/4/2016 at 1:04 PM, pfactor said:

I think I'm going to have to decide between spending around the same amount of money for either a SlickStart or new Tempest fine wires. I'm leaning towards the new spark plugs since I haven't seen any support for the SlickStart idea.

Oh, and the shop that overhauled the magnetos last year says they'll re-inspect and fix them for free. So we're going to do that as well.

The Champions are no bueno.  There is an “in between” regarding Champion massive and Tempest Fine Wire.  Tempest Massives.  I installed and they are a vast improvement.  Do you have a lightweight starter and extra cranking battery?  These made a nice difference in getting the prop spinning for start.  Good luck “finding the culprit in starting dilemma.  My bet is on the Slick mags/mag.