O290-D2 Carb issues?

[sdemeyer]

Hi everyone,
I'm running into a wall on trying to get my O290D2 running correctly. I purchased a rebuilt carb 10-3565-1 from ACS a while back and just now have gotten around to installing it. The engine previously was installed on my PA22 and ran fine back then, with the old carb. I just installed the engine with rebuilt carb on my Cub.

The problem I am having is I cannot get the engine to run between 1100rpm and 1500rpm for more than a few seconds without it surging and cutting out, like its running out of fuel. It runs fine at idle and runs perfect from 1500rpm to WOT. Just the midrange is not working.

I found that if I enrichen the idle mixture about 4 turns and apply full carb heat, the engine will run OK at the midrange rpm.

I've done all the normal checks for intake leaks and verified no fuel obstructions. All the screens are clean.

I suspect something wrong with the Carb but before I get ahold of MSA customer support I thought I would ask the smart folks here. Maybe I am missing something?

Thanks, Scott

[JPerkins]

Sounds like the transition circuit is plugged. Maybe with preservation oils that’s congealed?
I’d pull it and inspect the ports inside the throttle body. Maybe back flush with carb cleaner.
How long had it been sitting?


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[Gilbert Pierce]

I would contact ACS. That is a symptom of a low float level. The transition from idle jet to main jet thru the Venturi is delayed.

[Steve Pierce]

I would contact their customer support. Their troubleshooting chart says air bleed blockage idle tube or accelerator pump linkage misadjusted (too mush fuel from pump at acceleration.) There is a small plate with three holes and a cotter pin to adjust this.

http://www.insightavionics.com/pdf%2...b%20Manual.pdf

[sdemeyer]

Well it looks like I will be sending the carb back to MSA to take a look. I'm skeptical its a carb problem now after speaking to the owner of MSA/Tempest, Tim Henderson and hearing about the lengthy process each carb goes through. I'm at a loss on what else it could be. Its like there is a huge vacuum leak somewhere, but where?

[Steve Pierce]

QC is fallible, had to return one myself.

[Gilbert Pierce]

Be sure to let us know the outcome.

[PACERGUY]

Check your primer and make sure it is not leaking. A over rich mixture will also feel like it is too lean. DENNY

[sdemeyer]

The carb is now in MSA's hands to check out. In the meantime, I acquired another O290D2 carb just to see if the engine would run. The engine ran perfect at all RPM ranges. Most certainly the newly overhauled carb has some sort of a problem. Hopefully MSA will be able to find the problem, repair and return to me.

[Pacerfgoe]

If everything else checks out I bet fuel level is low......