Working on a L98 in a vette, had a vats issue but fixed that, I have spark, fp primes and good pressure at rails, will start with gas down its throat but dies eventually, injectors seem to not be pulsing. I checked inj fuses, they were good.I checked for codes and there are none. I have 12v at iinjectors and to distributor. Not sure what else to check, going back later to check purple and white wire coming from distributor module to see if it' sending pulses. Grounds are good, motor sounds real good and healthy. Its an 87 with 165 ecm. Anybody had a similar issue and can point me in the right direction? is the 165 in the vette same as 165 in the maroes and birds? Going to be diggging further, I'm hoping its the icm in the distributor.

 

Get a NOID light to verify for injector pulse. This is the way to be sure the injectors are or aren't firing. The ECM controls the injector firing by activating the ground. It's a batch fire so all 4 on the 1 bank will fire at the same time. The VATS system will cut the ground from the ECM so the injectors won't fire so I would check to make sure you got that sorted, from the sounds of it you may still have a VATS problem.
The ICM in the dizzy controls the spark advance, I don't believe it has anything to do with firing of the injectors.

 

I believe the ICM (using the pick up coil in the distributor) will tell the ECM when to fire the injectors?

 

So I verified I have spark, injectors are firing, all I need is gas. Runs great while supplying gas. Tested fuel pressure when turning the key to run, pump primes, can hear it, nothing at all at the test port. Does not squirt out any gas. I put 12v direct to relay with pump running, tested fuel pressure at test port with guage, nada. If I push down on test port valve with pump running it does squirt out very little, more like flows out. When priming you can hear the gas flowing to the rails but not pressurizing. Fuel pump was replaced a while back, it works, I can hear it prime, and if I put 12v to relay it runs but sounds weak. My guess is pump is toast. It is a ep241. Has anyone ever ran into an issue were pump works but is just weak and not fully pressurizing ? This is on an c4, tank is pretty clean, new filter. I don't think the line is clogged. Will be replacing pump and see what happens. Heck maybe just low on gas .