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ENGINE AT TIMES HARD TO START

 

PIPISTREL SINUS, Rotax 912UL engine has started first time since new. It has about 600 hours. Last week it failed to start after 5 attempts. After waiting 15 min. it started on the third attempt. Test flight flew fine. The weather was medium hot. 

 

I performed the following:

  • gascolator inspected and found clean. 
  • Fuel flow good. 
  • Electrical grounds are clean, torqued and marked.
  • RPM at ignition starting is between 260 to 300 rpm
  • Battery was bench tested by supplier to “like new conditions”
  • K&N Air filters freshly cleaned and oiled
  • Inspected spark plugs. Gap was good. No wear. Velvet black as usual, resulting from taxing and gliding approaches and landings, Usually using low rpm. 
  • Balanced carburetors statically and dynamically. They where pretty good.  
  • I checked that the throttle & choke fully close. 
  • Fuel is fresh

 

Engine started first time for about a week. With flights nearly twice a day. Yesterday it required 3 attempts to start. Test flight afterwords was good. (Once it starts it never sounds or smells flooded and runs smooth)

 

It now appears to be an intermittent problem. Once it starts, it runs very well. The Sinus is a Motorglider. I rely on my motor to start in flight ofter. I am concerned that the next soaring flight might result in a field landing. 

 

ANY ADVICE?

Should I send my Electronic Modules to be bench tested next?


Thank you in advance

Gino


Gino Cavicchioli
 
  • Re: Rotax 912UL difficult starts sometimes.

    by » one month ago


    Does the aircraft have a fuel return line with a electric fuel pump purge the fuel lines and fill the carburetor bowls before start up? You may have vapor lock condition in the lines after last shutdown due to high engine compartment conditions.


  • Re: Rotax 912UL difficult starts sometimes.

    by » one month ago


    Thank you for your reply Garret to my present saga. 

    Pipistrel has installed on my Sinus a return fuel line. I have a mechanical fuel pump. 
    Difficult starting occured in the morning and early afternoon. I dont think temperature was a factor. 

    This is a new issue. I have had no problems for the first 600 hours. 

    Gino Cavicchioli


  • Re: Rotax 912UL difficult starts sometimes.

    by » one month ago


    Did you change fuels? An electric pump with a section of clear fuel line on the return side would show air/vapor in the system.


  • Re: Rotax 912UL difficult starts sometimes.

    by » one month ago


    I know this comment may be getting old, but put some ice in a gallon ziplok bag. Don't over stuff it because you're going to drape it over the ignition module and tuck in in around the side. Let it sit 25 -30 miuntes and try a start. Full choke and crack the throttle. If it starts right up you need new ignition modules.

    OR

    You can take the modules off and send them to Lockwood in FL. to be tested.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-574-1080 Home (TRY HOME FIRST)
    520-349-7056 Cell

  • Re: Rotax 912UL difficult starts sometimes.

    by » one month ago


    Good morning Garrett

    Thank you

    The fuel I use is ethenal free high test automotive fuel. Same stuff I have ben using from the same supplier. It is fresh since I fly a lot. (Over 110 hours in the last 3 months, 40 of this hours are soaring with engine off)
    Today is the third occurents. It would not start streight out of the hanger. Oil temperature 25C. That rules out air/vapor lock 

    Gino

     


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