Zenoah Fuel Starvation

[Sam Groves]

I picked up an old Komatsu Zenoah G320AVS. It seems to have not been well used and is suffering from a fuel starvation problem. When I strip and clean the carb (fitted new carb kit), it runs sweet for a few mins but then cuts out (it did this before installing a new carb kit). If I drip fuel directly into the venturi, it starts up again and then cuts out. There is no primer on this model. If I suck on the fuel line I get a nice tot of premix, so I assume the fuel feed through the tank is fine. Any suggestions? Many thanks. 

[Khriss]

Still replace the fuel pipe ( obvs filter is flowing well  !  ) and the puffer pipe if it has one  ( impulse or vaccum pipe ) could be a crankcase seal too . K

[Stubby]

48 minutes ago, Sam Groves said:

I picked up an old Komatsu Zenoah G320AVS. It seems to have not been well used and is suffering from a fuel starvation problem. When I strip and clean the carb (fitted new carb kit), it runs sweet for a few mins but then cuts out (it did this before installing a new carb kit). If I drip fuel directly into the venturi, it starts up again and then cuts out. There is no primer on this model. If I suck on the fuel line I get a nice tot of premix, so I assume the fuel feed through the tank is fine. Any suggestions? Many thanks. 

Possible tank vent blocked and pulling a vacuum ?

[Paddy1000111]

13 minutes ago, Stubby said:

Possible tank vent blocked and pulling a vacuum ?

That's what I suspect. If it was a fuel pipe or crankcase issue then it wouldn't start at all after the carb rebuild as won't prime. 

 

Have you tried having the tank half empty and when it cuts out just undoing the fuel tank cap to see if there's a hiss and then put it back on and try to start? If you have a full tank it wont take long for it to pull a vacuum and cut out compared with a half filled one

[Sam Groves]

I'll give the tank vent system a test. Much appreciated.