late 70's model Johnson 4hp

[Franny]

Hi yall,<br />Our 4 hp Johnson runs for less than a minute and dies and then takes several pulls with throttle and choke adjustments to run for another few seconds. I am trying to get it to run good again. My question is what size spark plug should I use (also gap size) and what is the gas/oil ratio? I want to make sure I have the right stuff. Thanks

 

[Paul Moir]

Re: late 70's model Johnson 4hp

Welcome to iboats, Franny.<br /><br />The spark plug reccomendation depends on the precise year, since the ignition system changed in the late 70's and the spark plug recommendation along with it. Post your model number and we can figure it out.<br /><br />Either way, the Gas/oil ratio is 50:1 87 octane gas to TCW-3 rated outboard oil. It has been since '64.<br /><br />Gap is .030" too. <br /><br />Sounds to me like the first step in diagnosing your problem is to make sure gas is flowing freely to the carb. If this 2hp has a built-in tank, then disconnect the line a the carb, and see how well fuel flows from the tank with the petcock open. If it has a fuel pump, try pumping the primer bulb while it's operating to see if that helps it run.<br /><br />I hope this helps!