1989 3.1 won't start

[bxd]

1989 Buick Regal 3.1, about 160k miles.

This is my dad's car. Unfortunately he tends to do the absolute bare minimum to keep it running and won't be convinced to keep up with the small problems before they turn huge. So he was driving the car for months with it idling poorly. Bad enough that at red lights he'd have to throw it into Neutral to keep it from stalling.

The exhaust developed a large rust hole and he took it to an exhaust shop. They deemed the catalytic converter past its life (it's original) and replaced it. Lowered it off the lift and the car wouldn't start.

We had it towed home. I checked fuel pressure, 40+ psi ignition on and stays strong through cranking.
Checked for spark, got spark everywhere. Tried spraying starting fluid into the intake as he cranked the car over and sure enough got it to start and run if I keep spraying.

So my gut feeling at this point would be the fuel injectors, but before I throw parts at it I thought I'd ask here. Any chance it could be EGR, or IAC? I believe EGR does nothing at idle, and I believe if it was IAC, once we got the car started, if he gave it a little gas it would keep running right? Once I stop spraying, it dies right away.

I am not sure if this is another important data point, but he tells me that before the exhaust work was done, he had to accelerate carefully. Too much throttle and it would cut out as well.

If it is the fuel injectors, I'm having trouble understanding why a change in the CAT would cause this behavior??? I tried doing an ECM re-learn but this thing won't idle at all!

Thanks!
Brian

[FiredUpZ28]

IAC valve could be one thing. It opens up the air stream to make sure the car is getting the perfect amount of air at idle. The EGR I dont think would cause it to idle horribly but its possible on regular gas if its not working, its an easy item to check though. I tell everyone, get a haynes. LoL. It shows how to check all the necessary sensors/valves/other emissions components. Another thing would be the O2 sensors. If the car thinks it is running too rich or lean it will run sluggish, or not at all if its too extreme either way. Make sure you check for a vacuum leak in the intake as well, sudden drops in pressure, like stabbin the gas will make the car bog if theres an air leak somewhere. Could be a lot of things, good luck and post with the results!

[CNCguy]

I would not think that the fuel injectors would all stop working at one time. Check everything over and make sure all of the electrical connections are properly plugged in. Perhaps the shop knocked something loose. Next step would be to make sure you have power to the injectors. Then use a noid light or analog volt meter to check that the ECM is firing the injectors. With fuel pressure and a signal, you should be getting fuel to the cylinders.