CIS First start - no start help

[C-Pierce]

Hi,
freshly rebuilt 2.7 CIS. runs great for 2-5 seconds then might back fire and stops running.
Maybe only firing when the cold start injestor fires?

re-built with Rick Cabell a good friend and Porsche Guru, His Mother is dying and he does not have time to help me untill who knows.
So I am gonna tackle it tomorrow
any ideas? on where to start.?

got spark and new injectors, fuel is good, great spray pattern, we had the whole CIS apart and cleaned and refurbed all parts.

is it possible there is an air lock in the lines? fuel starvation?


Car ran great when I/we pulled the motor.

[rrsrsr]

Did you prime the system w/ fuel before firing it up??

I agree w/ your hypothesis that the cold start valve firing allows the car to run for the first couplle seconds.

[C-Pierce]

Please help me understand how to "prime" I did not do anything specile. I turned it over a few times to get the oil pressure up without the fuel relay in. then we tried to start her up...

I love MFI, CIS is too finicky...

[rrsrsr]

-Turn key to 'on' position (do not start the car)
-Remove air filter cover & air filter.
-Lift up air sensor plate for a few seconds- you will hear the fuel pump and the injectors sparaying. Only do this for 3 seconds or so as you don't want to flood the cylinders.
-Then try starting the car.

[JP911]

If you had fuel spraying through the injectors than the system should be primed. Your mixture may just be way off (especially if you disassembled the air sensor arm and mixture screw). I would try starting the car (cold) and while it's running for the brief period try pulling down on the sensor plate and then pushing up on it to see how it affects the mixture (pulling down richens and pushing up leans). If the cold start injector is the only thing keeping the car running then you may be way to lean. This is just a place to start.

[Paulporsche]

You could also try richening the mixture some easily identifiable amount, say 1/4 turn. This way you canb put it back where it was if necessary. If you have a CIS fuel gauge, you can check the cold control pressure. You might also want to check the ignition system and look for air leaks.

[Won]

Originally posted by JP911
pulling down richens and pushing up leans

Isn't it the other way, it has to be putting in more fuel when the sensor plate is lifted with more air, so when you lift it by hand it richens the idle mixture?