I'm trying to figure out an approach to figuring out an ignition problem on my MegaSquirted '87 Trans Am.

Details:

• I drove it to where it sits now. It was running fine, but it wouldn't restart after I parked it. Why do I suspect an ignition problem? The MS has the 3 indicator LEDs, one of which flashes with an ignition pulse while cranking. Mine isn't flashing.
• Car- basically a TPI 305, it doesn't look anything like a TPI 305 (single plane manifold, LS throttle body, LT1 heads, 4/7 swap cam...) but it uses the original harness (since it's a '87 and the MS is running speed density things like the MAF wiring is removed), original small cap distributor... It ran well when parked, no signs of any problems.
• The MS uses the adapter board we had on here from way back when, so the MS is in a stock ecm case plugged right into the harness using the adapter
• The ignition is a small cap HEI and a Crane Hi6 ignition and their matching LX92 coil using their adapter harness. No hacking, it's all plug-in. The rest is typical, I believe it has a new Accel cap and rotor, MSD 8.8 wires, NGK TR55 or TR6 plugs.
• The only other known electrical problem is that the HVAC fan ground doesn't work. I have a jumper from the fan ground terminal to one of the strut studs to get the fan to work. The problem was around for months before the ignition problem but the reason I mention it is that I know that the ground for that ultimately winds up on stud on the back of the driver's side head (no idea why the factory chose that for something on the other side of the engine bay) which is in the vicinity of the ignition wiring, and I can't see or even touch most of it.

Suggestions?

 

Ignition module inside the cap. Check all your grounds

 

Open tuner studio and sync your project so that your data is reading, crank the engine, you should see the tach read some rpm if not the ecu is not seeing a tach signal, if you do see rpm then you have an issue between ecu, icm and coil, the ecu sends a square wave signal to icm and the icm pulses a ground signal to the coil.

 

also with the OEM ECM i have found that if you can't get a start but it cranks the tach guage will track the engine speed even though the engine doesn't fire. If the tach needle doesn't move while cranking it has always been in my experience the ICM under the rotor cap is bad