Interesting.....I had a similar problem with a 3.5 hp sprint. It would run for a few minute, then the primer bulb would suck in then it would die,it often wouldnt start till cool. A few suggestiins were offered but unfortunately with no resolve. I would create a vacuum behind the bulb then had to wait till it popped out of its own accord....I will check this issue you had and see if it relates to my issue:)
Cheers on the good outcome Uni:)
