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.