Camaro 1990 3.1 no start. Changed ECM, kept old PROM. temp sensor, knock sensor , ignition module, spark plugs, fuel filter, checked fuel pressure good, spark good. timing ok. Checked vaccum hoses and replaced the ones questionable. Car sounds like only one cylinder is firing when I crank it. Looked at plugs and found all but #6 rich burn #6 normal. Can a bad PROM (MEMCAL) cause this?

If the stock injectors or even stock replacement (rebuilt) injectors are in the engine, they are bad. With the Multec injectors the coils short out preventing them from firing properly.

Can see Southbay Injectors for a set of Bosch replacements.

RBob.

assuming that the iron head 3.1 has the same injectors as the aluminum head 3.1, then you're looking at 16.7 lb/hr stock injectors.

Injectors are good, checked with node light.fuel press is good too. I will install new PROM and will post.