Actually surprizingly long!

What happens is that the fuel moves through the line at a relatively slow speed as it is vaporized at the carb.

Once the bubble ( or in this case the several inches of air ) hits the carb, if there is still pressure in the tank the air gets pushed out relatively quickly as it can flow out of the carb need much more quickly than fuel.

The engine stumbles and is helped by the inertia and airflow, but it may just resume operation.

6" is extreme, but I've seen engines dealing with 3" of air in the line without shutting off because of the above.


That's not to say having air in the lines is ever a good idea...


But his point is absolutely correct, that fuel - DOES NOT - "stick to the back of the tank" as often espoused by even veteran RC'ers.

It's the remaining fuel in the lines that keeps the engine going, and the clunks DO become uncovered and start sucking air.