My 18 hp B&S on my Garden Tractor won't continue to run. It is about 10
years old.
I mowed the grass a few weeks ago and it ran fine until I was almost
done with the 1 acre mow job.
It started to lose power as I was climbing a small hill in the yard,
then it died. I was able to restart it, but I had to close the choke
fully in order for it to stay running, and the it only ran for a short
distance before it shut off again.
This week, I could not get it to stay running for more than a few
hundred feet before it shuts off like it no longer got gas or the key
was shut off.

What I did:
Pulled the fuel filter off and blew through it from both ends. No
obstructions, and I could see the screen was clean inside. I blew
through the gas line that goes to the gas tank and was able to blow
bubbles in the tank.
I replaced the fuel filter with a piece of tubing, just in case it was
the filter.
I removed the gas line from the carburetor and the gas ran out freely.
I pulled the cover off the carburetor and checked the diaphragms. No
holes, tears or problems.
I ran it with the air cleaner off and the in-line fuel filter removed.
No difference.
The gas is not old and the tractor is used year round for lawn mowing
and snow blowing.

As far as I can figure, it runs out of gas or perhaps heats up to where
it seizes up. Is there an oil pump that may have gone bad?

--
Bill