73 4hp johnson

hobojoe

Cadet
Joined
Nov 3, 2011
Messages
17
well 3rd time hope its a charm.my brothers 73 4 hp johnson (4r73c).runs great in the barrel when take it out on lake wont start, spits and sputters,back fires.we have replaced fuel pump,fuel tank,filters,hoses had the carb cleaned and rebuilt at a boat shop . i didnt go with him last night but said started on first pull but only ran for a few minutes then never started again hes leagaly blind but his girlfriend 2 sons went with him to drive. the last time i went it would run but backfires ,oh he replaced the plugs had ac delco put in champions this time,the only thing i can think of is fuel mixture but know its 50:1 the back of the 2cycle oil as i read it 4oz oil to three gals gas? could the size of the boat (14ft old alluminum boat) just be to heavy for the motor? thats what he thinks. he bought it last year ran fairly good but this year has gremlins or something. thought we had it fixed with the new plugs ran better then ever in the barrel. any ideas are helpful thanks for looking joe/mike
 

nwcove

Admiral
Joined
May 16, 2011
Messages
6,293
Re: 73 4hp johnson

sounds more like its maybe running lean? hull size/weight shouldnt make the motor act like you describe.
 
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