The problem is solved.
It was situated well in the regulation system of the level of gasoline in the carburetor.
In fact, a particle of rubber, of 1mm of diameter and of 8mm of length, blocked the "pointeau", guided by floater, which regulates the arrival of the gasoline in the tank. That this drowned itself, thus permanently.

Bizarre, Tank, filters (air , gasoline) and all others internals parts are clean. I don't known the origine of this rubber's particle !

Thank you Soulie to have me to direct to the solution, as well as Ello for his help.

I remain your obligee

Friendly

I'm glad you solved the problem, tranquille!

Cheers
Soulie