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912S starting problem

in General Tech Discussion 13 years ago
My 912S (TT 360 hours) is very difficult to start after 3 to 4 days of inactivity. Once the engine starts operation is normal. The problem arises only after 3 to 4 days of inactivity. Engine has been thoroughly checked by competent mechanics and the ignition system is the main suspect. Any suggestions? Many experts are baffled on this one. Thanks.

  • Re: 912S starting problem

    by » 13 years ago

    Hi Dudley,

    Humor me and try this.
    Try this one test before you do anything else. Put your battery on a charger over night, even if you think it is charged. Then try it the next morning and let us know. The other thing to try now that the weather is warming is don't use full choke and some can get away with no choke and only cracking the throttle better starting. I tell some people that don't want to leave a battery on a charger to put the charge on a timer like you might use for Christmas lights and let it only charge 4 hrs per day. Use a good float charger and not a trickle charger.

    If the engine's age is within the last 6 years I tend not to think it is an electrical problem. many people try to go that route, but after a lot of frustration find it is 2-3 little fuel issues contributing in to one. On one of the other threads I posted an incident where this very issue of hard starting happened and after many gave advise about electrical he took it to a well known Rotax mechanic and it was only a few small fuel delivery isses that combined to make life miserable.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: 912S starting problem

    by » 13 years ago

    Hi Dudley,

    Here is the post:



    NOW ONLINE
    Senior Boarder

    Posts: 41
    Karma: 4
    Hi All,

    Just food for thought.

    I'm posting a fragment from another site that discusses Rotax 912 engine frequently. Here is the first post and then there were many ideas. The bottom line as you will see in the last post is that simple and sometimes multiple maint items can and usually do make your problem. So you need to be a good diagnostition and start at "A" then "B" then "C" your problem solution may be elusive and frustrating.
    This post shows the simple things that were corrected to fix the issue, yet other people wanted to bounce all over trying to solve the problem.

    Here we go:
    I bought my 2006 CTSW 2 years ago. It was a trainer and currently has 1039 hours tt. It has always been a little cranky about starting. It would intermittently simply refuse to start but once it started, it ran like a top. Lately it has gotten more difficult to the point that it won't start at all. Before you ask, yes it is turning over in excess of 250 RPMs. I recently had the carbs rebuilt by Lockwood and as a precaution replaced the fuel pump. I generally use Mogas but have tried Avgas to verify if the fuel was up to snuff. I also changed the spark plugs and they are wet after attempted starting so, I'm confident that the fuel system is not at fault. I've visually inspected the ignition system but can find no fault there (loose wires, bad grounds, etc.). I am based at KZPH (Zephyrhills, Florida) and there is nobody at my airport either knowledgeable enough or willing to help me. I've taken the Rotax training (service and line maintenance) from Dean at Lockwood and last summer I obtained my LSRM-A rating just so I could do my own maintenance.

    So...how can I check the ignition system? What is the likelyhood of both modules being bad? How can I check for a spark? Roger, Tad you guys could solve it in a minute but unfortunately you're not here. Short of pulling the wings and trucking it down to Sebring, I'm at a loss.



    The finial answer:

    ... And the winners are. Roger and Tad for their diagnosis of my carb problem. I brought the plane to Tad in Sebring and he correctly assessed the myriad of minor issues that combined to make a large problem. A poorly adjusted choke, too high an idle and too much tension in the cables in combination with unsynchronized carbs were the problems. Tad did a great job and in no time at all, I was flying back home. Thanks Tad. I'll be seeing you again. You've brought the pleasure back to my flying.



    Having small issues combining to make one frustrating one is very common. My help to everyone is to follow the maint. prescribed by Rotax schedules and maint work. Make sure who ever does your work is familiar with what they are working on and has been to a Rotax school. It really does save money in the long run. For example: If a part is becoming worn, replacement right then and there may save other parts from excessive wear or an expensive repair. Having a mechanic that knows what they are doing may save you money on the hourly rate. Example: An untrained and inexperienced mechanic may take 2-3 hours to repair something and a trained experienced mechanic may take 1 hour. Finding a worn part in advance of a failure also saves you from expense.


    p.s.
    Tad Olmsted is a highly qualified Rotax mechanic in Florida and he would be a good pick for a mechanic.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: 912S starting problem

    by » 13 years ago

    Many thanks Roger
      
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  • Re: 912S starting problem

    by » 13 years ago

    I've done that with the charger, spark plugs are new, carbs have been overhauled. All fuel issues sem to be OK. Leaning toward an ignition problem, possibly the ignition/starter switch. Thanks for your input. I'll post the solution when it's found.
      
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  • Re: 912S starting problem

    by » 13 years ago

    I don't have a great deal of experience with the Rotax engines but when I went to the Rotax school one of the issues that was brought up was pilots not flying enough and the batteries loosing some of it's output. The engine needs to spiun up to at least 350 RPM to generate enough current to fire the plugs. If the battery bis not at a full charge state it may not have the storage capacity to spin the starter fast enough.

    I have a Battery minder that I leave connected all the time when I'm not flying. When ever I want to start the engine it spins up like a Top. A plus to using a Battery Minder is it will also desulphate your battery which is primary reason for battery failures. It is not uncommon for aircraft batteries to last twice as long as normal when using a Battery Minder. May I suggest you contact Dean Ritter the Battery Minder Distributor at 405-627-9350 or check out his website www.thebatteryminder.com. I have used the Battery Minder for years and it's the best insurance I ever had that my engine will always start quickly.
      
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