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Need help pap top 80, starts but cuts out


Marty

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Hello to all, just joined and would appreciate some advice, I have a pap top 80, it has been lying idle for a year, it will start but cuts out at 4500 rpm upwards, so far I have checked the fuel supply to the carb, cannot see any problem, carb stripped , no blockages found.

thanks

marty

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I think you might find that the carb membranes may have dried out and could have developed small perforations/cracks.....  This would cause the problems you described... working OK at low RPM then leaning out and stopping intermittently.  The membranes control the fuel metering and are critical components. It's recommended you change them every year, regardless of flight hours.  Also check your fuel pipes for tiny leeks- the fuel primer bulb is also a notorious contender for causing trouble- sometimes the rubber hardens and small cracks allow air in which throws off the metering too....    If not used for a long time, sometimes the non-return valve can stick also.  Again replace every 2 years for peace of mind.   
The carb membrane kits are not too expensive.

 

 

 

GD

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I've removed my primer bulb on mine , for no reason other than if it's not on there I don't worry about it going wrong ' I blow through a tube at the moment prime that way . Think I'd like the primer back on now though . Do any top 80 owners kill the engine while up high or what ever . If so do you have prime with the bulb for the restart .

cas .

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Cas- yes my Top 80 (Miniplane) has the tube primer method too, and it seems a great idea- very simple, and very little to go wrong with it.   Generally I find that I really only need to prime the engine after a long session without running....   If restarting an engine during a flight, generally i don't need to prime at all....  I only prime the engine at the first flight during a days flying.

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Make sure the choke is not fixed on/open (if there is one on the carb). I have seen this before where the engine just gets flooded after a few mins.

Also check the pipe attached from engine to carb, which transmits pressure changes. This gets worn out / cracked after a period of time.

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