Random shutdown in '90 DB1 with B17 swap

I have a '90 DB1 that’s had a B17 swapped into it. Approximately every two days, the car will die as if somebody cut the injectors or ignition. The way it consistently restarts is to depress the clutch and start it by turning the key. Just depressing the clutch and popping it back up again does not work.

The swap was originally done in a crude manner - just throw it in and get it going. Over the years it’s been there, various problems have existed but I’ve managed to iron them all out… except this one.

  • At first, there was a homemade conversion harness, but I’ve since replaced it with a purchased one
  • I was missing various vacuum lines, wires, and sensors, but all since added (I pulled my, now retired, stock DB2 along side and literally moved everything that was missing or out of place into the DB1)
  • I’ve replaced the engine grounds and positive terminal after cleaning the contact surfaces
  • The distributor on the B17 was months old when the donating car was purchased and opening it up would suggest so, but I’ve changed the cap and rotor
  • I resoldered the main fuel relay, then tried another resoldered one, then tried a known working one from my DA9 just to be sure

Any insight would be appreciated. I’ve done some searching through these forums and elsewhere, but the symptoms are never quite the same. I still try what’s suggested, but people usually jump on “main fuel relay” and “dizzy” when an Integra randomly konks out.

I feel like there’s a hint with how I’m able to get it started again. While moving, if it dies, depressing the clutch, turning it to “accessory”, then back to “on”, and then raising the clutch again, never works. But, if I depress the clutch and turn the key directly to “start”, it always fires up.

So what is happening when turning to “start”? We know everything short of lights and ignition are denied power to focus on the starter. But turning to “accessory” does almost the same thing, save for the stereo, but actually cuts ignition power too.