I have a 3 liter flat six using cis injection and I have one dry/dead cylinder.

I can't figure out what else to look at but I have excluded the following things.

fire/spark - timing is normal and the plug and wire are getting appropriate spark

Injector appears to be spraying normally in volume and spray pattern as compared with the others

I guess I am left with air or valves or possibly the fuel distributor as the culprit?




what is my next step? What else could cause this?

What are your compression and leak down numbers. The mixture must be compressed or the cylinder is not working for you...

compression on this cylinder is within normal at 160lbs.

A 6cyl compression test recently showed the same thing all the way around.

Is a compression test enough or is there a significant benefit to having the leak down (I don't have the tools)?

A CIS system can have a problem with the fuel distributor that makes one cylinder so lean it won't fire.

Here's how to check it.....

Pull all the injectors and put each of them in separate glass jars the same size.

Turn the key on and lift the sensor plate in the fuel distributor and hold for 30 seconds.

Compare the amount of fuel in each jar. I will bet that the dead hole has a LOT less fuel going to it.

good call Clay, there was a significant difference in volume on that cylinder compared to the others.
Where do I get a replacement? I see that python rebuilds them, are those trash?

Your next step is to see if it follows the injector or the fuel distributor. Swap the injector on the bad cylinder with one of the others and repeat the test.

If it stays with the cylinder, you need to replace the fuel distributor. Those are going to be $$$ rebuilt. Check some of the online sites like evilbay or the bird board's 911 parts and see if someone is selling one after putting on carbs.

Here is the link to the new/rebuilt fuel distributors on the Bird Board.

Injectors are easier to come by and easier to change.