fbpx
Login

 

Jump to Forum..

engine miss when aux fuel pump turned off

in 912iS Technical Questions 8 years ago

  • Re: engine miss when aux fuel pump turned off

    by » 8 years ago

    If the pressure is a little low on one side of the fuel delivery when you switch then it will miss. Maybe the pressure is not equal on both sides for some reason?

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

      
    Report

  • Re: engine miss when aux fuel pump turned off

    by » 8 years ago

    The regulator takes a second to adjust to the slightly different pressure?
    I notice the pressure is always different between the two pumps and the aux pump does have a different/longer route through the plumbing of the pump pack.
    PumpLayout.jpg (You do not have access to download this file.)
      
    Report

  • Re: engine miss when aux fuel pump turned off

    by » 7 years ago

    Hi Peter,
    did you ever find a reason and or a solution to this problem ?

    I have had this happen a couple of times recently also...most disconcerting !

    Thanks

    Glenn
      
    Report

  • Re: engine miss when aux fuel pump turned off

    by » 7 years ago

    Glenn I have not found a solution. I changed the fuel pumps and same thing happened. a mate who has the same engine has the same problem. my LAME says it is common and not a concern as the engine runs fine. I live with it and once I turn of aux in flight I have no problems.
    Thank you said by: Glenn Martin
      
    Report

  • Re: engine miss when aux fuel pump turned off

    by » 7 years ago

    I have experienced this and at least in my case, I think it may be related to vaporization of the fuel. Occasions when the condition is experienced or not experienced is temperature (and fuel) related. When doing an engine run up for the first flight of the day- normal. All operations during cool or cold weather- normal.
    After a long cool down period in cruise flight- normal.
    I have only encountered this condition when 1. using unleaded fuel with ethanol. 2. during warm or hot ambient conditions. 3. during or after prolonged climb to cruising altitudes. 4. with somewhat restricted fuel flows.(aircraft manufacturer plumbed fuel hoses from tanks to fuel valve with 7mm hose (slightly less than that called for by Rotax).
    Using "Both" on fuel selector provides increased fuel flow since I used 5/16: ID hose from the valve to the engine.
    If the engine compartment is "hot" and the fuel valve is on either Left or Right the engine will react to deactivation of the AUX fuel pump. If I have the fuel valve on "Both" (the fuel flow is increased) the engine will not react to the deactivation of the AUX fuel pump.
    Since I very rarely use 100LL my observations may only reflect variances.
    Using the above experiences I have been able to completely avoid engine disruption when managing the fuel pump.
    Thank you said by: Glenn Martin
      
    Report
You do not have permissions to reply to this topic.
Related Topics
Title Category Replies
Need to find 912iS Fuel Filter General Tech Discussion 8
fuel pump failure General Tech Discussion 4
Blended 100LL/Unleaded Fuel & Oil Change Interval 912iS Technical Questions 2
Fuel pressure rise 912iS Technical Questions 7
Clarification on fuel usage General Tech Discussion 2
Follow Us

Recent Videos

Safety First!

 

To receive critical-to-safety information on your ROTAX Engine, please subscribe to
ROTAX-OWNER.COM

ROTALK News



ROTALK NEWS Episode 5
Rotax-powered Sling aircraft from The Aircraft Factory, the AVMAP Navigation and engine monitoring system, and the Rotax powered Tucano Experimental and Light-Sport Aircraft.



ROTALK NEWS Episode 4
ROTAX's 915iS-powered Aquila A211 test aircraft, the Scheibe SF-25C Falke (first-ever 912-equipped aircraft!) and ROTAX factory in Gunskirchen, Austria.


ROTALK NEWS Episode 3
Michael Smith's Rotax-Powered Searey Circumnavigation, the amazing Rotax-Powered Lockwood Aircam and Anthony Caere's chimpanzee rescue operations.

Prize Giveaway!


SUBSCRIBE NOW
to automatically enter this years draw!

Login