I’m working on restoring a 1989 Camaro irocz, 350, TPI, and I’m having cold start issues, mainly when the car sits for a little more than usual.

once it starts and warms up, it runs fine, but that initial start after sitting, is a bit rough. It takes a couple of cranks and initially it smells like it’s burning rich.

For context, I have installed new injectors, new fuel pressure regulator, new fuel pump, sender, and filter, new fuel pump relay and plug, and replaced all sensors excluding the MAF and TPS, but i did test and calibrate the TPS, new plug wires, distributor and cap, and ignition coil.

I did end up finding a ADS performance chip in the ECM so I don’t know if that’s messing up the car.

thoughts?

 

Have you watched fuel pressure for holding after prime ?

 

I did it before I did all of the work, but I haven't had a chance to do it again because I have to go borrow a pressure gauge again from a friend of mine. Before the work it wasn't holding pressure, but also misfiring and barely starting at all, so obviously I made some improvements, but not quite where I need to be.

Like I said, after it starts, it runs fine. It's hard starting it after it sits off for a while. I know that the pressure should hold for a while after shutting the car off right? Assuming it's not, and keeping in mind everything I fixed/replaced, can you think of anything else?

 

A lot of parts stores rent fuel pressure testers. I’d still pull the vacuum line off the fpr look for evidence of fuel. Try even starting the car with the gas pedal held down. If it pops or sputters you have fuel entering the engine with injectors not pulsing. After prime if the pump check valve and fpr and injectors hold you can hold a prime for up to 10 minutes before slow bleed off.

 

so I haven’t done the fuel pressure test yet, but I did test the power at the fuel relay, and while I get the constant 12V, I’m not getting the ECM signal for prime once I turn the ignition to on. The fuel pump is not kicking in to pressurize the fuel rails prior to crank.

 

A1 at the ecm is relay control. Might check it for 2 second power on ecm power up.
you could have a bad ecm.

 

in working on tracing the wires to ensure there are no breaks or cuts, but worse case scenario think I’ll install a manual prime button.