whats wrong with the lawn mower?

I have a troy bilt self propelled lawnmower with a briggs and straton 6.75 engine.

i am having problems keeping the mower running. I have to prime it about 7 or 8 times to get it to start and then it runs for about 10 seconds if lucky and quits. to get it started again i have to repeat the priming , it runs a few seconds and quits again.

any ideas?
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