Hard start when hot

[Chuck Wills]

I've got a 914/6 conversion with a CIS injected 3.0. Essentially a stock 1980 SC motor with '83 pistons, headers and MSD ignition. It starts fine when cold, but not when hot.
When I try to re-start shortly after shut down, it will momentarily fire, then die.
Then it just cranks and won't catch for a while. It could take 10 seconds, it could take 2 minutes to fire. When it does catch, it acts like the plugs are fouled -- runs rough until I blip the gas a few times. I have noticed when this happens that if I just let the fuel pump run I can hear bubbles coming up in the fuel tank. Is it vapor lock?
The CO was at 5.0%, and has been reset to 2.0% with no effect.
The guy that built the motor says he thinks the injectors are bad -- letting the pressure bleed out when shut down. The injectors were used, and I don't know how old they are.
While were on the topic, another nagging problem has been, durring warm up, the idle speed sill surge a bit. It will almost die, then rev to 2500 or so then almost die....., but it only does this for a minute during warm up.
Any ideas?

Thanks,
Chuck

[Wayne 962]

Hi there. My 2.7L engine does the same thing. I have assumed that the mixture is set to rich, and I have been meaning to turn it down after I fix all the oil leaks.

I think that the sound of bubbles in the tank is normal. I think that it indicates that your gas is flowing and not vapor locked.

Whenever I have this problem, I remove the air cleaner and push up on the air plate on the inside of the CIS system. This makes the injectors 'meow' and sends gas directly to the combustion chambers. This almost always works to start the car.

It's really a problem with cars that don't have a good battery, like my was for a while.

Why don't you post this in the 911 section as well. I'm sure that there are some CIS experts in there...

Hope this helps,

Wayne