Strange. I mean, in the old days, pumping the gas worked on carbureted engines because there was a piston that actually pumped fuel into the intake manifold to get the engine started.

On these cars, pumping before starting probably does nothing. Pumping usurping starting probably introduces air and fuel that bypasses the idle control mechanism.

I agree that fouled plugs could be the cause, as introducing a lot more air without atomized fuel could help clear the cylinders. But I also wonder if the idle control or starting fuel algorithm could also be faulty. I guess I don’t know how the starting procedure on these cars works in terms of idle control versus some other mechanism.

Since its injected and doesn't have an accelerator pump like a carbureted engine, I'm assuming you're referring to giving it gas while cranking it over, rather than to prime it prior to cranking it. On my 99' C2 I give it zero extra fuel with the pedal, and it always fires right off and idles. I'd also be extra careful to avoid revving it at all above idle speed upon start-up because of lack of oil pressure/circulation and operating temperature. Do you suspect a vacuum leak? If you loosen the oil filler cap to intentionally create a vacuum leak when it's idling, does the idle change?

I’m currently working through a similar issue with warm starts. Pumping the throttle adds air not fuel to the mix which makes me think I have either a faulty Evap system or leaking injectors. The rich mix is then thinned out by pumping the gas pedal and starts every time. May be related to your isssue or not. Keep us posted either way and I’ll do the same.

As as an aside I have no CELs, no problems filling up and no whistling bottle noises that typical accompany a faulty evap purge valve so like I said, I have some digging to do.

Have you tried turning the key on and off a few times before engaging the starter? I️ dont know if the 996 fuel system imhas a return or not, but the fuel line has to be under pressure and a pressure leak within the system can initially starve the injectors for fuel for a few seconds. Turning the key on and off would cause the pump to run and pressurize the system. Also could be a weak/failing pump.

Funny enough, I ran my 996 out of gas yesterday, and it sputtered and died. But if I depressed the accelerator a bit, it would run just long and well enough to back it into a parking space.

So when you say ‘pump,’ I wonder if what you are actually doing is opening and closing the butterfly valve whereby the opening part of the cycle is what’s actually helping the car start. The way to validate my hypothesis would be - next time instead of pumping, try holding the throttle open at 25% of 50% and leave it there to see if it’s has the same affect.