Yet another CIS Mystery
 

Sorry to go over much traveled ground but I've managed to turn an (almost) perfectly running '77 CIS car into a non-starting mess. I've read most of the CIS threads - even before this problem and have had some experience with non Porsche CIS in the past but this one has me frustrated.

Trying to improve a slight uneven idle, I did the "field test" and the idle and RPM improved significantly when pushing up. Based on this I decided to make a very small mixture screw adjustment. I only moved the screw less than an eighth of a turn and since then cannot find a position where the engine will run.

I've kept the idle screw within 1/4 turn of the original setting and spent hours moving it a tiny amount each way. There are places where it will run for 10-15 seconds, but it always dies.

Along the way, I managed to get the idle bypass screw way out of whack and need to know if there is a good starting point as far as initial number of turns.

Can it be that these settings are really that sensitive or is it possible that I've created some other problem with the flow sensor? I could change the bypass screw by several turns before this happened without killing the engine so it seems there should be a wide range where it will at least run long enough for me to see if I can get the mixture back in range.

Any ideas would be much appreciated.

Ron

Replying to my own message -

Sorry for the exercise - but the problem seems to have gone away. I waited an hour or so and finally got the car to run at higher RPM's long enough to burn off lots of fuel in the cylinders. I may have seriously flooded it early on while playing with the sensor plate - or perhaps something else was temporarily wrong, but now the bypass and mixture screws seem within range. I've been able to make adjustments to both while idling and the field test seems to work as well. I think I've even cured the uneven idle I started out chasing.


Tomorrow I'm going to continue to check out the system and make sure the car road test's OK but tonight is going to be a lot more restful than I thought a while ago.

Thanks for listening!

Ron

Glad to be of assistance, Ron!
;)

Glad to help Ron!