Oldsmobile/Buick Repair: 1991 skylark 3.3 no start, throttle position sensor, flood mode

Question
I have a 1991 skylark that won't start. Just purchased the car ran great for 5 days. Replaced plugs,wires, fuel and air filters just for maintaince. Ran fine 2 days and would sometimes not start. Scanned pcm when it doesn't start there is no injector pulse on scanner or at injectors.Rpm and maf read normal. Replaced icm,ecm, crank sensor. 1x and 3x signal good to icm.Checked all grounds to ecm and engine.When it does decide to start everything looks good on scanner and lab scope.The only weird thing while running the rear 3 cylinders are only firing 1 spark instead of two per revelution.when it runs I have jerked on all the harnesses and it doesn't make a difference. Do you know what the signal the icm feeds the ecm or do you have any other ideas?

Answer
Hello Randy,
You checked for pulses to the injectors, but is there battery voltage to the injectors?
As long as the key is on, there should be voltage, and the ecm provides the pulses by completing the ground, and the injectors operate when grounded.
But if there is no voltage, you could have a loose, or bad fuse, or ignition switch.
Another thing is the throttle position sensor. If it happens to be sending a wide open signal, the ecm could go into clear-flood mode, and not pulse the injectors. I think you could unplug the TPS, and it will set a code, but should switch to open loop, and run on default values, like during cold start open loop.

Van