Have a 1990 with 3.1 TBI engine. Fuel pump + filter replaced about a year ago. Well maintained (plugs, wires, dist. cap+rotor replaced/in good shape). Fuel pump relay energizes when key on and when engine runs. I hear the fuel pump whirring in tank while relay is energized. It always starts, but only runs for a few seconds each time (about 2-5 seconds).

I removed the plastic cover on Fuel Pump relay and looked at the relay while engine stalling. It stays energized all the time, and is still energized while the engine stalls. De-energizes about 4 seconds AFTER the engine has stopped completely.

Spark is obviously there because if I spray starter fluid into throttle body bore when it's about to stall, it will stay running until i release the spray can BUT i can see that the injectors quit spraying at that point so it only continues to run on the starter fluid!

What could cause the ECM to stop the ground pulses to the injectors? If the Ignition module isn't sending any reference pulse to the ECM, shouldn't the spark be gone too? Why the heck do i have spark and power to the Fuel pump relay but no injector pulses?

Even more interesting, why do i have injector pulses for the first 5 seconds after starting and then they disappear but sparking continues???

IIRC the ignition module in the distributor controls spark, you can have spark from the distributor, but the ECM will control the timing of the spark.. I think if the EM isn't controlling spark you will be at a default for spark timing...

The Injector is controlled by the ECM... Not 100% sure if you have a Ignition control issue or an ECM issue or an issue between the two... Hard to say...