Small Engines (Lawn Mowers, etc.): Lawnmower wont run, internal passages, air filter

Question
I have a basic Murray walk behind lawnmower that will crank and run for a second, but then shut off. Then, after it stops, it won't start crank again until I've primed it again.
The air filter was recently replaced, and I had experienced starting problems with it when starting for the first time this Spring (old gasoline) but it had run well before now.
Thanks much!

Answer
If it will only run with choke or a squirt of fuel, you will need to thoroughly clean the carb, including pushing a piece of tag wire through all internal passages and following up with carb cleaner.  Start with fresh fuel and you should be set.  Hope this helps.