Help Please, 1991 firebird injectors aren't pulsating
 

Thank you for any help. Anyone can provide me. I've searched the forum. Read articles on people with similar problems. But haven't found the answer to mines.

I have a 1991 pontiac firebird trans TPI, with a 383 stroker and holley stealth ram. With msd ignition. At first I was having a problem with the secruity light being on. I bought a resistor set. An found the correct reference. An also a bypass for the VATS. Still the injectors will not pulsate. I have a new distrubutor. 12v at the injector wires. Fuel pressure 50LBS. I have spark.

I also bought a new computer. I didn't replace the prom. Some how i had 2 of the connectors swapped plugged in the computer. Figured i may have fried the computer. Could this also have damaged the prom or cause problems in other area?

Re: Help Please, 1991 firebird injectors aren't pulsating
 

Couple of things going on here. I'll hopefully be able to help out.

With a stock '91 TPI harness it isn't possible to swap two of the ECM connectors. They are keyed so that can't be done. This may be a re-pin of a TBI harness to a '7730 harness. So be aware that there may be an issue there.

VATs does disable the injectors, so unless properly bypassed to the ECM that can be an issue.

Check the injector fuses, there are two: INJ1 & INJ2

If still using the OEM injectors (Multec), which I doubt you are, they will short out and prevent all injectors from firing. There is only one injector driver is the '7730 ECM.

ECM needs to see distributor reference pulses (DRPs) in order to fire the injectors. A quick check to see if the ECM is getting DRPs is to: key-on, engine off, listen for fuel pump to run for 2 seconds and stop.

Now do a short crank of the engine. If the ECM is getting DRPs it will then run the fuel pump for another two seconds.

If the new ECM you purchased was from an auto supply store, they do not come with a MEMCAL (PROM). Need to swap that in from your old/current ECM. The engine will not run without a MEMCAL in place.

RBob.

Re: Help Please, 1991 firebird injectors aren't pulsating
 

sorry it took so long to reply.. It's keyed to not fit... Apparently i made it. I had to push one of the pins back in the harness. I changed the memorcal from the old ecm to the new. Both of the fuses are good.. The Fuel pump is coming on and shutting off with the switch. And also oil pressure switch is engaging. WHile engine is being turned over. Yes i have aftermarket injecters. I Ohm them out. THey checked okay. I also checked the grounds to the engine block.