honda vtwin requires increased choke to run

miraclewhip

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Honda Gx620 ran normally for several cutting cycles. Engine began hunting at high speed and faltering. Opening choke about 1/4 helped maintain slightly less than full throttle.After 30 minutes,choke had to be increased to 1/2 ,just to keep running,even with throttle at idle or any slower speed.There are no fuel filters to plug.HELP!!!
 

bertsmobile1

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There is a fuel tank that has an outlet that gets plugged with debris.
There is a main jet that gets plugged
There is a float bowl where all of the crud that the fuel filter would have prevented getting into the carb will build up.
And depending upon the exact model engine , most Hondas have a fel tap as part of the carb that can block and a sediment trap under the tap that can also clog
 

miraclewhip

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Thanks for your suggestions! What is fel and tap?
 

bertsmobile1

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The Fel is between the Y & I :laughing:
Should have been fuel tap.
On most Honda engines it is on the right side of the carb.
 

miraclewhip

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Thanks, I will proceed to check/clean carb and all lines and ports! I had started to replace fuel pump ,suspecting it to be the guilty party.I will report results when completed.
 

bertsmobile1

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FWIW when I took over the business there were 6 fuel pumps in his inventory.
Around 3,000 repairs latter there is still the original 6 + 1 Honda pump because the pump on a GX620 is a different size & the ones I had in stock would not fit.
Because I like to have parts on hand I bought 2 of them.
 

miraclewhip

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Cleaned carb and reassembled without replacing fuel pump. Initial start seemed fine without needing choke,but started losing rpm after about 30 seconds. Advanced choke and rpm increased.Removed gas cap and closed choke ,rpm resumed normal. Removed gas cap and removed gas cap vent valve,replaced gas cap and rpm resumed normal without choke advanced. Seems to be a combination of carb needing cleaning and restricted gas cap vent valve. Thanks for your advice. I failed to identify the mower, it is a grasshopper 618 with replacement engine,Honda gx620.The gas cap is standard Grasshopper.
 
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