Walbro Carb High Speed Needle Cuts Out - RCCanada - Canada Radio Controlled Hobby Forum
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Old 10-02-2010, 03:57 PM   #1
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Walbro Carb High Speed Needle Cuts Out

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My Zenoah G45 high end needle cuts out in the air at full throttle after about 5 seconds and the engine slips back to mid range throttle. I have to reduce the throttle to idle for a few seconds before the high end can kick back in. It is as if the fuel reservoir in the carb becomes drained of fuel and requires some time to refill . The screen is clean. I have tried resetting both low and high end needles with no success.

What should I do.

-bend the float lever to increase gas flow

-change the float spring

-something else. Could it be my ignition module, or change in back pressure on my diaphragm.

Any suggestions appreciated.
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Old 10-02-2010, 05:55 PM   #2
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Re: Walbro Carb High Speed Needle Cuts Out

check the pump diaphragm to see if its still soft and supple. If not, replace it, also check ign. battery pack, tank and lines etc.
Dave Collis
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Old 10-02-2010, 06:32 PM   #3
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Re: Walbro Carb High Speed Needle Cuts Out

A couple of things to consider
- is this a recent development, has the present set-up worked in the past, if so something has changed, the trick is to figure out what.
- is the engine cowled, I have heard of problems with changing air pressure inside the cowl during flight.
- it sounds to me like a fuel delivery issue. Possibly restricted fuel line or week diaphragm.
Hope you work it out.
That went well

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