Air lock ?

[SILGP]

My carb, a dellorto phbh seems to have developed an intermittent airlock.
The engine's been cutting out as if running out of petrol. While checking the fuel flow I accidentally discovered that occasionally fuel will not flow from the tank down the pipe. If I remove the pipe from the spigot at the banjo bolt, the fuel flows freely. I put it back on - it stops. If I tap the carb , bubbles form and it slowly flows again
The carb's been cleaned with carb cleaner and blown through with compressed air and the float seems to be fine but the problem still persists.
Has anyone got any suggestions ?
Cheers
Tony.

[missing lynx]

Is the breather in the fuel cap blocked?

[dickie]

New float valve? Sticky float?

[Rich Oswald]

Is the breather in the fuel cap blocked?

+1

[SILGP]

Thanks for the replies. I've tried it with the petrol cap completely off and it's still the same. Got a new float needle and the float looks as good as new.

[missing lynx]

Has the scooter ran ok before or is it a new build with a new carb?

[MickYork]

Might not be a carb' issue. Have checked your electrics ?

[SILGP]

Hi, I've put on a working CDI , HT lead, suppressor cap and also tried a new stator.
The engine was rebuilt around January, (mugello 225) and was run in and also did the vast majority of the NC500 which is when the problem started.q