recently on my 912is which is 18mths old I get a very slight engine miss when I turn of my aux fuel pump in flight. only lasts a second. does not happen when I turn off the main pump. if I have the emergency switch on it still does it. it does not do it again if I turn it back on after that unless I fly for a while. any ideas
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Re: engine miss when aux fuel pump turned off
by Rob Seaton » 9 years ago
Does the fuel pressure drop?
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Re: engine miss when aux fuel pump turned off
by Peter Mahoney » 9 years ago
Only 1 bar same as the other one does for a brief second. I put it on computer and noticed a slight drop in fuel flow from main pump.
Only the first time I do it. After that all normal.
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Re: engine miss when aux fuel pump turned off
by Roger Lee » 9 years ago
If it drops 1 bar (14.5 psi) for a second that would be enough to make it miss. This engine can't tolerate lowered fuel pressure like the carb version. Once pressure drops too much the engine will quit. On a test stand at Kodiak I pulled the fuel pump circuit breaker. The engine quit immediately.
Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell
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Re: engine miss when aux fuel pump turned off
by Peter Mahoney » 9 years ago
They both drop the same but only misses on the aux pump and only the first time.
Any ideas.
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Re: engine miss when aux fuel pump turned off
by Richard Boslaugh » 9 years ago
perhaps one of the pump bypass check valves is getting sticky
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