1970 merc 500 50 h.p. four

[tonman]

recently bought this motor for 50 bucks canadian. runs great, idols nice, manual start is easy 2 pulls choke then then one without, starts every time I put it in the water take off an only get about 30 mph outta her runns good like that until i shut it off then when i restart it hit the gas an only get 5 - 10 mph its driving me crazy please can anyone help me ???

 

[12Footer]

Re: 1970 merc 500 50 h.p. four

What's the RPMs when it starts back up and only goes 5 to 10MPH? If the RPM's are up where it belongs, it's the prop hub.<br />Otherwise (and I know this is really hard to do on the water), pull the plugs.Have a spare set handy incase you loose one or all.<br />Check for fouling.<br />You would also know this by a steady miss, or coughing.<br />It could also be an air leak in the fuel system ,anywhere from the pickup tube to the carb.