Loss of power doing climb

Hi Michael,

Sounds like a fuel flow problem. A flow restriction may limit the underload engine speed.

Did the problem start when the carburettors were "overhauled"?

How many hours has the engine done?

When was the last 5 year rubber replacement? 

Did the rubber replacement include all hoses, back to the tank(s)?

What of engine EGT readings ?

Inspect float bowls for contaminates.

Try flushing the fuel supply system by disconnecting the lines at the carburettor and running the Boost pump - inspect fuel flow into bucket for equal delivery. Check collected fuel for contaminants such as paint flakes, rubber , etc. 

I would also question your engine management technique. A Rotax 9 should be doing a MINIMUM of 5200 rpm during climb procedures.😈

Hi Sean,

Thanks for your answer.

Have been running 40 hours from carb overhaul and rubber replacement. 

EGT: Doing the happening there become a significant difference of around 180 degrees.

I will try the suggested. 

Hi Michael,

Have you had any more luck diagnosing this?

We have a very similar problem that we can't figure out with a CT SW - that started with installation of a new engine.

Michael

Hi Michael,

Yes we did find the source. My CTSW was not born with a Fuel Pressure sensor. After we installed this in the right place according to Rotax we were able to see that there was almost no pressure from the machical fuel pump (New). When we installed a Electrical fuel pump we could get the pressure to 4psi. However, It would drop to 1psi when engine rpm was increased.

The New fuel hoses was pressed to the Banjo bolt that goes from the Mechanical pump to the "distribution feed" that feeds both carbs. We found that this press fitting that was used was incorrect and had pressed the actual hose to the point where almost no fuel will get through. We replaced the hose and used normal hose clamps and now it works.

If fuel feed is not your issue I would definitely look towards the carbs. 

Thank you. Had your hoses been the orange kind  (silicone) with the pressed on fittings?

We have those and still wonder if they are part of the problem.

We also had a fuel pressure sensor installed to better troubleshoot.

We get between 2.6 and 4.8 PSI - goes toward the lower end when the engine warms up on the ground. Shortly after take-off it also goes towards the lower end, but then stabilizes.