1977 55hp Johnson erratic performance

www3

Recruit
Joined
Jun 18, 2002
Messages
4
Hello board,<br /><br />thanks in advance for considering my issue. My 1977 Johnson 55HP with very low hours does the following: Starts right up fine when choked at motor, revs good, but when getting under way may or may not lose power--if it loses power it will drop down to trolling speed even if throttle fully depressed. <br /><br />This loss of power has no apparent rhyme or reason: One day it will not do it, then will do it for 30 seconds next day, then (like this morning) will do it for 30 minutes. When power returns, it's without warning--will just rev ahead, almost like a blockage had been cleared--however, at low power, boat is not "missing".<br /><br />Have replaced plugs, checked fuel line, fuel filter, switched gas tanks thinking I got bad gas. Symptoms disappeared for three trips, then reemerged. Any help appreciated!<br /><br />www3<br /> :confused:
 

angus63

Captain
Joined
May 20, 2002
Messages
3,726
Re: 1977 55hp Johnson erratic performance

This is a 2 cyl.? Mine was a 74 and I had similar symptoms when a coil broke down intermittently. Check wiring first.
 

www3

Recruit
Joined
Jun 18, 2002
Messages
4
Re: 1977 55hp Johnson erratic performance

Thanks for the reply--yes, it's a 2 cylinder. Will see if I can round up a shop manual and will check coil.
 

www3

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Joined
Jun 18, 2002
Messages
4
Re: 1977 55hp Johnson erratic performance

BTW, I went back throught a bunch of the "dies at WOT" posts--however, have not been able to make sense of the seemingly random nature of my power loss at WOT, and the fact that once it clears for a trip, I've got good power the rest of that trip<br /><br />www3<br /> :confused:
 

fireman 757

Petty Officer 1st Class
Joined
May 18, 2002
Messages
276
Re: 1977 55hp Johnson erratic performance

It still sounds like a coil breaking down. Sometimes they do it intermittently. You also might have some garbage in your high speed jet. Might be picking up stuff in the tank or carb bowl. Once it clears it it's fine but then will pick up another bunch.
 

www3

Recruit
Joined
Jun 18, 2002
Messages
4
Re: 1977 55hp Johnson erratic performance

thanks for the note fireman--noticed my depthfinder going blank yesterday so need to do some igniton/wiring diagnostics--plan to try to clean carbuerator also and visually inspect. A lot to learn but need to be able to do some of this stuff.<br /><br />take care,<br /><br />www3
 
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