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912ULS not starting

  • amyminnich
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3 months 2 days ago #20562 by amyminnich
912ULS not starting was created by amyminnich
912ULS will not start after it has been sitting. A little spritz of starting fluid and she immediately fires off, runs great. Will restart immediately after shut down, but that first start just isn't there. A couple weeks ago we tried to start, got nothing. Pulled her in a parade through town and when the parade ended just for grins, I attempted to start -- she fired right off. Any ideas will be welcomed -- thanks

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  • Roger Lee
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3 months 1 day ago #20565 by Roger Lee
Replied by Roger Lee on topic 912ULS not starting
Could be marginal battery. Some first start morning jump the battery and see. If it cranks right up then you know. If it still fails move on. So many discard the battery as a culprit. Needs to be ruled in or out,,,,, but my guess is clean out your idle jet.
It is also possible that one of the starting circuits in one of the ignition modules is gone out and it is only trying to start on one.

Clean the idle jet first.

Your starting technique and rpm setting at start may be a contributor.

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

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3 months 1 day ago - 3 months 1 day ago #20569 by DHeal
Replied by DHeal on topic 912ULS not starting
Make sure that when your CHOKE ("Starting Carb" in ROTAX parlance) is in the OFF position that the choke lever arms are resting solidly against their stops and there is a wee bit of equal slack in the choke actuator cables. Also be sure that both choke actuator springs are properly doing their intended jobs.

In my experience, the 912 starts best when one follows the factory starting procedures. For cold (or initial) starts, I use 1/2 to full choke initially -- be sure that the throttle is FULLY CLOSED. As soon as the engine fires, I feed in a bit of throttle and start easing the choke off. For warm/hot starts, I use no choke at all and just crack the throttle open (My idle is set for 1,650 rpm but I always endeavor to keep it at 1,800 rpm or higher). These procedures work very well for my RV-12 and other 912s I have operated -- usually, you can't even see the prop move before its running.

Poor starting performance can also be the result of a tired battery or spark plugs gaps being too wide, The battery may seem like its spinning the prop well enough but it is not fully up to the task -- try a known good condition battery. Ignition trigger gaps could be checked as well to ensure that they are within spec.
Last edit: 3 months 1 day ago by DHeal.

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2 months 1 week ago #20771 by stingsport
Replied by stingsport on topic 912ULS not starting
Battery first! Had The same bad starting issues intermittent check several things last thing I tried I clean the two ground clips coming from the ignition modules attaching to the aluminum intake manifold wire brushed and cleaned it’s been starting flawlessly sense that

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