1977 75 hp johnson starts runs good dies after couple minutes full throtel

[johnson301979]

starts up runs good, go about 5 minutes dies, could i have mixed gas wrong? i put 16 oz to about 4 gallons, also shoots gas out bottom carb

 

[Vic.S]

Re: 1977 75 hp johnson starts runs good dies after couple minutes full throtel

Well the fuel mix should be 50;1 which is near enough 1 pint in 6 gallons but the fuel mix will not account for your problem.

I sounds as though you are suffering from loss of fuel after a few minutes.

check the tank venting
the fuel lines for possible air ingress and for any partial blockage.

Can you keep it running by pumping the priming bulb. If you can and its not one of the above the fuel pump could be defective.

However, I dont know what you mean by, "also shoots gas out bottom carb"

 

[Fl_Richard]

Re: 1977 75 hp johnson starts runs good dies after couple minutes full throtel

Gas spitting out the carbs could be a reed valve problem... or a float problem.

 

[lindy46]

Re: 1977 75 hp johnson starts runs good dies after couple minutes full throtel

Gas spitting out the carbs could be a reed valve problem... or a float problem.

Bottom carb needle stuck open/float not floating? That could account for the gas running out.