Hard to start 912 ULS

I have had troubles starting my 912UL for apprx one year. At first I thought it was a temperature issue (because of winter in Sweden) and started to heat the engine with a hot air fan into the air intake. It seemed to solve the problem, sometimes... Then I thought it was a fuel issue and ran the electric fuel pump and pushed the throttle before engine start. It seemed to work sometimes... Then I started to thing about ignition. I changed spark plugs at 400h (158h ago, about a year), and used WhackerP12 on the plugs. Then I recently read the ROTAX MML 12-20-00 about not putting any Whacker on the first 3 threads. So, I properly cleaned the spark plugs and their fittings, adjusted the gap to 0,7 mm, put on Whacker sparingly and the engine fired up just fine, even in cold and damp weather. Before that, it had been almost impossible to start. I feared to go to other airports because of the starting problems. Seems ok now.

Hi Matt

You may have a failed sprag clutch.  Check the starter draw at cranking (use a DC clamp meter on the power wire to the starter) if you have less than 75 amps.

Refer to the other materia in the SB, it has a complete checklist of items to look at 

On the subject of oil.  Mobil 1 V twin is NOT the right oil.  It has no gear additive to protect the gearset (much higher wear) than needed.  I would strongly suggest going to the new RPS oil as it is a full synthetic and tested in all Rotax 9 series.  If you must use Mobil 1 us the "4T" oil that is formulated for engines with a wet clutch.  

Cheers

Matt, it’s been eleven years. How about circling back and letting us know what solved your problem?