1977 merc 70hp 700 stumbles while accelerating

My previously well-behaved '77 Merc 700 has developed a bad habit on its last two outings....initial start up and acceleration to top speed is fine, but after dropping back to a slow crawl in no-wake zones, it tends to stall when I push the throttle forward. If I do it slowly, it'll eventually get up to full speed and run OK, but that's not gonna make my daughter happy on her skiis. Vent on fuel tank is open. Could this be fuel pump? Plugs? By the way, what are the right plugs for this engine...I just bought it this spring, and I'm not sure what's in it, or if they're the right things.

Re: merc 70 stumbles while accelerating

You can improve this situation by adjusting when the carbs start to open as the throttle is advanced. Later is better. If the carbs open too soon you'll get that stumble. Study the linkage adjustment on the left side of the motor. Note the one that opens the carbs and make it do it LATER.

Jeff

Re: merc 70 stumbles while accelerating

Ethanol and your fuel.J

Re: merc 70 stumbles while accelerating

Thanks for the tips...I'll check out the hoses, filter, and diaphragm. While I'm at it, what are the proper plugs for this engine?