70?s Merc 650 stalls after 10 min.

[mc jimbo bob]

I finally got my boat in the water this season and after starting a little hesitantly it ran fine for about ten minutes then suddenly died. I was able to restart it but my confidence was shaken.

Ran the boat again and did a compression test ? 140 psi on all cylinders but noticed what looked like oil on the spark plugs. I checked the fuel filter ? nice and clean. It might be my imagination but the exhaust smoke looked a little blue to me.

I was wondering if I should rebuild the carbs?

What other maintenance should I do on this old motor? I have only had it a couple of years. Replaced the water impeller earlier this year.

Fuel pump rubber membrane, check the timing, replace the distributor?

 

[starcraft1982]

Re: 70?s Merc 650 stalls after 10 min.

I would definately clean/rebuild carbs and put fuel pump kit in it.I also would suggest replacing the fuel line assembly as ethanol may be breaking it up inside(bulb included).Then,install a fuel water separator,run some seafoam through the engine and then always run a little additive(seafoam,marine stabil,ect,)with your gas unless you run it very frequently.Keep oil mix correct.