1986 camaro 305 fuel injected. will not start I have taken the cat coverter off to replace. tried started before putting new one on . engine cranks great but will not fire. started up before i took cat off, could having the cat off make a difference?

Hold the ignition switch just off where the engine cranks after it starts, if it stays running you need to replace the ignition starter switch. This is the switch at the bottom of the steering column that the key cylinder operates via a rod. See photo below.

as it is the basic 305 block the differences may be fuel injection over carburettor which may require sensor attachments but basically the engine should just slot in place.

I think I would be looking at the crank angle sensor and/or the cam sensors on this vehicle.It seems to me the engine isn't getting the signal to fire up.What happens when you squirt some fuel into the combustion chamber ? If it fires up I would be looking at cleaning the injectors.If it doesn't fire up What's the pressure on the fuel rail. does it have a buy pass pressure valve on the rail.Some suggestions good luck

check for cracked or disconnected vacuum line,fuel filter,pcv valve,or egr valve

did you change the map sensor?try that or the egr valve sensor

Have you checked for spark or tried shooting carb cleaner in the intake to see if it will fire?

Is it flooded? Have you tried holding the accelerator to the floor? You have gas spraying out of the injectors when cranking? Does it even try?

fuel filter sounds like it is a prime suspect. if cat convertor it will be extremely hot possibly glowing as this goes on.

Does it crank? Do you have any codes? Check engine light? Do you have spark? No spark check coil, and connections, also it would be nice to know what year it is. Get codes read. No crank check battery and starter. No codes or lights check crank position sensor, make sure your pcm is good after replacing your ignition mod you could have blown it if you did do it right. (engine computer) Check cam sensor if applies. Crank and cam could prevent it from starting and I know one I think cam controls pcm's fuel delivery on gm's

have you checked the fuses?