1978 Johnson 55hp won't idle

[rook]

I have a 1978 55hp Johnson Sea Horse that won't idle worth a damn, it idles worse in the water than out. It runs great past idle. It has good compression, I've cleaned the carbs and messed with the trottle linkage and mixture screws, but I can't seem to remedy this problem. Any suggestions would be appreciated.<br /><br />Thaks,<br /><br />Sean

 

[steviecops]

Re: 1978 Johnson 55hp won't idle

Hi Sean<br />I have a 1980 Johnson 55, and that doesn't idle great either, but I have been able to improve it a lot.<br /><br />I thoroughly cleaned and rebuilt the carbs, then did a link and synch as per the manual. New fuel lines throughout, rebuilt fuel pump, new plugs, one new ignition coil and cleaned every earth connection on the engine. Also did a decarb.<br /><br />What really made the most difference though was when I replaced the thermostat. The engine had been running too cold and never got up to the proper temperature.<br /><br />As I said, this engine still doesn't idle really smooth, but is a lot better than it was.<br /><br />You say you messed with the mixture screws on the carbs? My engine has fixed orifice jets that can't be adjusted. I'm sure yours is the same? I would get a manual if you don't have one and work to what's in there.