50hp pops when started

[Rich1540]

was running good ,then motor over heated do to thermastate ,changed head gasket becouse it was bad also ,now when started it pops out the gasket behind the fuel pump were it bolts to block, changed gasket and still the same checked pionts good ,checked carb all seems good but cant figure this one out it really getting frustrating !
anyone had this problem before ?
model 507x5a
50hp force
us marine

 

[Rich1540]

Re: 50hp pops when started

well i pulled top plug off and it quit popping and ran smooth !
pulled off bottum plug off and did the same thing but almost died out why any ideas would be great and thanks in advanced !

 

[Rich1540]

Re: 50hp pops when started

got it to take gasket and pops out exhaust left key on and #1 coil got so hot it melted in about 1 min. could this be condenser ,checked and traced all wires three times i take this also the problem causing my backfire !