Hard start with full tank

[chrisrappl]

I have a 2005 Piaggio Typhoon 50 that I have had since it was new (two cycle - carburated with 3,600 miles).

It has always had a problem starting if I fill the tank all the way. The engine acts like it is flooded and I need to hold the throttle wide open and crank for a long time before it will fire.

The service manager warned me about this and said to never fill the tank all the way to the top.

I had the body panels off for maintenance recently and expected to find a charcoal canister evaperative emmissions system.

My plan was to perform a canisterectomy to see if it would solve the hard start when full problem.

I couldn't find any evidence of a canister or even an overflow line from the tank.

The only thing I saw was an exhaust connection back to the carb through something like a reed valve.

Has anyone else had this flooding/hard start condition with a full tank?

The petcock appears to be vacuum actuated. I am starting to suspect that it is not closing properly and allowing gas to continue reaching the carb. The needle valve should stop the gas, but it may not be able to when the tank is completely full.

Any advice would be appreciated.

Is there a known repair?

[Daniel-S]

Iv had a problem simular to this on pit bike's, the fuel tank was completely sealed with no way off getting air into there meaning when you opened the tank it sucked tons off air in, I solved it by getting a new filler cap with an overflow off the top allowing the air through.