Modern Vespa

I recently cleaned the carb on a 2006 LX150 to get it running after being stored for almost two years. Replaced with fresh fuel and started with no issue. Ran fine the first trip up the street when I tested it out. Next time my wife hopped on to ride, the engine stumbled when opening the throttle but then would catch up and run fine up to full speed. Tried letting it warm up, but same response.

This sound like an accelerator pump issue. I took the carb apart again and pressed the pump by hand. I got a small spit of fuel but not what I would call a spray or continuous stream. Is that right?

How do I confirm it is the accelerator pump? If it is the pump, can this be repaired/cleaned or need a new carb?

Thx for any help!!

quick check: with fuel in the bowl and the carb assembled, depress the pump arm or plunger-- look inside the venturi, you should see the discharge nozzle spray fuel toward the butterfly.

no love? then the orifice is blocked or the plunger is stuck.

also, blow out the idle jet and circuit for good measure-- just don't lose the tiny washer and rubber grommet for the air/fuel mix screw that sit behind the spring!

-g

Hey greasy125.

Thanks for the post. When pumped by hand, a small fuel spray is seen inside the venturi. I also tried rotating the accelerator and it triggers the accelerator pump as expected.

Could the timing of the accelerator pump from rotating the accelerator be off? Maybe caused by stretched accelerator cable?

Babino