Pulling my hair out here. Just finished a TBI swap in my 86 K20. ECM is wired to 12v constant, and 12v on key/crank. Engine will crank, injectors pulse, distributor sparks, but will not fire. Doesn't even try. No spit, no sputter, just cranks. Advancing and retarding the distributor a few degrees changes nothing. If I hold my foot to the floor while cranking, it will sputter a bit and occasionally backfire through the TB and at least try to start. Seems like dist is 180° out, but I've checked four times, and I'm reasonably certain I'm on the money.

For sake of argument, this is how I checked for TDC/distributor position: Pulled plug #1 (drivers side front), finger over the hole, bumped starter until compression was felt, crawled under truck and rotated flexplate until timing mark and balancer were aligned at 0°. Rotor on distributor was pointing at cyl #1. Rotated dist until rotor was aligned with plug #1 on dist cap. Harness and coil inputs are facing the firewall, slightly towards the driver's side. Reinstalled cap and double checked plug wire routing.

One thing I'm not certain on; the HEI dist had one pink wire providing 12v to the coil. I used that wire to power the TBI coil. However, on the modular plug for the coil, there is a pink wire and a white wire. My understanding is the white wire is only used for a tach signal and is not needed for anything else. Am I correct?

Really frustrated. Hoping someone has some insight.