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912UL Not Getting Fuel

in 912 / 914 Technical Questions 11 years ago
Trying to get 912UL back in service after storage. On RANS S-12S, pusher.

1. Carbs just reworked at Lockwood.
2. Throttles and Chokes mechanically synced and operating.
3. Mech fuel pump operating well.
4. Tanks below carbs.
5. Fuel passing through tank return line.
6. Electric fuel pump off.
7. Bowls of carbs have fuel.
8. Engine cranked with full choke (throttles at idle & also applied).
9. Pulled lower plug to inspect for fuel.

Result: NO fuel indications on plugs.

Shouldn't I have a ton of fuel on plugs and in cylinders??

Thanks
Corey

  • Re: 912UL Not Getting Fuel

    by » 11 years ago

    Doesn't seem anyone is willing to take this on.

    My next step is ensuring spark is occurring. This will take a while since I'm not getting even a pop out of it.


    Anyone have Dr Rotech unit for rent?
      
    Report

  • Re: 912UL Not Getting Fuel

    by » 11 years ago

    Hi Corey

    The first thing I would do is make sure there is oil pressure if it has not been run for some time.

    If that is ok, remove the air filters and spray some starter fluid into the carbs while you are trying to start it.

    If it doesn't start, the you can start looking more to the ignition side for a problem.

    Mark
      
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  • Re: 912UL Not Getting Fuel

    by » 11 years ago

    I would focus on the carbs but you can buy a xenon tester from Mac/snap-on that will confirm the plugs are firing. you will not be able to see the arc very well without the tester but you will be able to feel it if you are unlucky enough to be holding the plug when cranking the engine mags on.
    -Remember the choke is not a choke in the true sense, it is a starting carb so you will not likely too see sopping wet plugs.
    -Make sure you are getting enough rpm from the starter; does a boost battery help?
    Thank you said by: Corey Bonnell
      
    Report

  • Re: 912UL Not Getting Fuel

    by » 11 years ago

    More information for those pulling engines from storage.

    1. All resistances checked on generator and ignition system - all nominal.
    2. Ignition modules checked at Lockwood - checked OK.
    3. Checked all wiring on engine, ignition, and regulator/rectifier.
    4. Ignition switches checked for continuity.
    5. And...at long last I checked the plug gaps. WAY OFF. Rotax states .023-.027 for 912UL. Gaps were at least .035 or greater. Re-gapped all plugs.

    I haven't tried a start yet on these chenges and checks yet. Maybe the 1st will be a lucky day. I still have to get the timing light on it to check for spark, but if it fires with the new gaps, I may not need to. Otherwise, my final checks will be for a spark with the xenon light and the resistance of the plug wires and caps. Right now Tach showing 240 RPM with the rev counter. Manual states 120-200 for cut-in. After that, this thing may be a coffee table.

    I'll let everyone know how it goes.
      
    Report

  • Re: 912UL Not Getting Fuel

    by » 11 years ago

    NO START!

    1. Checked voltage at regulator "C". Reading Battery voltage.
    2. Tried to start with new plug gaps. Nothing
    3. Tried boost battery for more cut-in rpm. Getting nearly 300 RPM. Nothing.
    4. Put xenon timing light on number two cylinder plug wire.
    5. Checked all resistances per manual. All checked nominal.

    Nothing. No light. No RPM reading. No spark.

    Is there anything in the wiring of the regulator that would cause this?
    Should I try running wires straight from ignition modules to battery ground?
    Is there any way to test for a charging coil failure?

    BTW: Rotax Installation manual shows direct wiring from start switch providing power to ignition modules. This doesn't make any sense to me. The only connections to the ign modules are my four-pin connectors to the trigger coils, two connectors to the ign grounding switches on the panel, and two pins connecting the charging coils to the ign modules.

    Nowhere do you connect power from the start switch to the ign modules. ??????????

    Any ideas on where I go from here??????

    Thanks in advance.
    Corey
      
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