Dellorto vhsh,when motor is running gas comes out of float bowl whare the vent hole is?

SOURCE: Poulan 14" chainsaw, fuel coming out of fuel cap vent

The fuel cap has a rubber check valve in the top. This check valve allows air to enter the tank so fuel can flow. Much like the vent on your gas can. Sounds like the check valve in the cap is stiffening and not flexing. Best bet is to buy a new cap. Most caps like that sell for less than $3.

SOURCE: lawn mower running problem

There are no adjustments for the carb., however, in the bolt that holds the bowl on, there is a small hole in the threads that must be clean in order for it to run right. It is a real small hole on either the 3rd or 4th thread from the top.
Hope this helps

SOURCE: It lobes with or without load. Cleaned airfilter, drained float bowl, checked oil, fresh gas

Try the filter in the gas tank.

SOURCE: Toro Model 20017 pump bulb, runs 2 seconds then quits ....

I had the same problem. I took off the carborator and cleaned every opening I could find. As I was reassembling it, I noticed the holes in the bolt that holds the bowl on were plugged. I hadn't notice that fuel flows through the bolt to the carborator. I cleaned them out and the mower started fine. I suspect it was that all along. I would try cleaning out those holes before you take off the carborator.

SOURCE: mower surging

let it surge, it will usually get better as it warms up. These 6.5 Hp engines are fine except they have an cheap badly designed carburator. Nothing can be done about this problem. They all surge eventually.