PaulD writes:

I am helping a neighbor with his push mower. He has a 6.5 HP Briggs
and Stratton engine.
When I prime the engine with gas using the little button on the mower,
the engine starts up with no problem, but then quickly peters out. Is
this likely a carberator problem? or a fuel supply problem? Are there
any quick fixes that we can try.

Pressing bulb supplies gas, so it starts.
Sounds like the normal gas delivery system doesn't work since it dies out.

Google found a lot of possibilities.

I am willing to give him a hand, but I don't really want to get into
rebuilding his carb or something like that. I might be willing to
clean the fuel line. I didn't notice any fuel filter on this unit,
but I might not be looking at the right spot.

Try these Google search terms:

briggs and stratton 6.5hp starts then stalls

-or-

We've got a nice lawnmower repair place near by...maybe there's one
in your area.

--
Dan Espen