Cutting out at top end

[Joe Ricard]

Just documenting what I did to fix an issue so someone else will benefit.

SR max started cutting out after about 3 seconds or so at 12K RPM and higher. It wasn't consistent with regards to RPM. Felt like it just shut off but would pick up again after lifting off the gas for a blip.

Changed jet didn't fix it. 172 to 168 NOPE not it. ( it was 56 degrees 1029 bar, ADR 100).

Changed fuel filter and it looekd ok so decided to change fuel pump BINGO!!!!

Apparently the bowl was draining faster than the pump could re-fill it.


No more cutting out.
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Arrow AX-8/ Rotax Sr.

[Justin Martin]

Also, just for info,

I had a similar problem, however above 12000 I ran really lean, and under it was overly rich.

I was running no tube on the bowl breather ports. When I finally got sick of the over-flow fuel mess it made I installed a new tube. The opening was cut and everything, however the tube was too long. The carb couldn't breath causing it to go lean at higher rpm. I first tried cutting the opening larger and it didn't work. Then a venture in creative thinking, I looks back in to some of my aerodynamics classes (for aerospace engineering) and just like a fighter jet's performance is reduced by LONG intakes, the same happened with my breather tube. I shortened the tube and instantly fixed the problem.

Make sure the carb can breath!

[Ray Chiappe]

I have had the same problem with the feul pump. My backup was used, but it cured the prob. Now I rebuild or replace about twice a year.

[Cory Ross]

I have been trying to figure my engine out for doing the same thing. Above 12000 it will cut out and almost act like it is on a limiter. If you stay on it it seems the take a few seconds then breaks through and jumps quickly up to 12700-13000 and runs normal.

When you are talking about the breather tube is that the small black tube that goes from one side of the carb to the other with the opening cut in it where the tube is bent?