Chummy fuelling problem

[Rogerchummy]

I had exactly this problem on my 1927 Chummy. I found that the solution was to put a T-junction in the pipe leading from the tank and fit an open-ended vent pipe to this t-junction which allowed vapour to escape from the fuel before it arrived at the carb. Apparently modern fuels give off far more vapour than some years ago and this excess vapour can effectively block the delivery of fuel from the tank to the carb. It immediately cured the problem which has never recurred since. As my vent pipe is transparent plastic, you can see the vapour bubbles as they escape which proves that the diagnosis is correct.

Email me and I can send to a photo of the set-up