I have a friend who has a 912 ULS powered Zodiac at our airport. He is having a problem getting the engine to start. The starter spins the engine, but no light off. There are no Rotax Mechs in our area. I had two 912s previously and tried to help him get the engine to crank and run. Here's what I did and maybe you've been there, done that and can offer a hint. The engine would sometimes start but run so rough that it sounded like it was coming off the firewall.

1. I check to see that there was fuel getting to the engine:
a. pulled the fuel line at the mech fuel pump and ran the facet fuel pump. No fuel came out the line.
b. Checked to see if the enricher valves were closing when the knob was pulled. They were, based on the movement of the leverage.

c. hooked up an external gravity fed fuel tank/line to the fuel pump and cranked the engine but still, no joy. Engine "almost" started one time but severe vibration.

2. removed a spark plug and turned the engine over using the starter. There was a spark at the plug.

3. The spark plug showed moisture, indicating that fuel was reaching the cylinder.

I initially thought the problem was the enricher circuit, but based on what I saw, it is not that.

The owner told me that on the occasions that he was able to get the engine to start that it ran extremely rough for several minutes, then as the engine warmed it smoothed out. He said that if the engine ran 10 minutes he could shut the engine down and it would crank up immediately and run smoothly.

I think that it is a carburetor/fuel issue, but I'm not sure.

Any suggestions?

Thanks,