"I have a 15 hp Johnson outboa
"I have a 15 hp Johnson outboard motor. 1994 I think with model and serial number J15ECEC R08189838 mounted on a 14 ft Livingston. I purchaced the motor 8 months ago. With 2 persons on board it purrs like a kitten at any rpm and up to 15 mph. With 3 persons it misses amd the speed drops to 10 mph and with 4 persons it misses and the speed drops to 7 mph.
Three days ago with three on board after an hour drive and three hours fishing it would only achieve low rpms. I changed the plugs and it worked fine ( good rpm with some missing) for 30 minutes and then it went back on to slow rpm ( about half way ). I cleaned out the plugs and tried it again with 2 persons aboard. The motor ran great for 30 minutes, but after we stopped it would only achieve half the rpms. I replace the plugs with dry ones and the motor preformed fine for anouther 30 minutes or so. Again only low rpm after a stop to fish. This has been repeated another time. The carb was rebuilt one month past, in an attempt to fix the missing problem without success. I have tried spark plug types QL16V,QL77JC4,L-77J4. Both the plugs appear the same after each time. The motor never lost high rpm, it just would not regain it after stopping or slowing down. My mechanic is at a lost. David
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"I have a 15 hp Johnson outboard motor. 1994 I think with model and serial number J15ECEC R08189838 mounted on a 14 ft Livingston. I purchaced the motor 8 months ago. With 2 persons on board it purrs like a kitten at any rpm and up to 15 mph. With 3 persons it misses amd the speed drops to 10 mph and with 4 persons it misses and the speed drops to 7 mph.
Three days ago with three on board after an hour drive and three hours fishing it would only achieve low rpms. I changed the plugs and it worked fine ( good rpm with some missing) for 30 minutes and then it went back on to slow rpm ( about half way ). I cleaned out the plugs and tried it again with 2 persons aboard. The motor ran great for 30 minutes, but after we stopped it would only achieve half the rpms. I replace the plugs with dry ones and the motor preformed fine for anouther 30 minutes or so. Again only low rpm after a stop to fish. This has been repeated another time. The carb was rebuilt one month past, in an attempt to fix the missing problem without success. I have tried spark plug types QL16V,QL77JC4,L-77J4. Both the plugs appear the same after each time. The motor never lost high rpm, it just would not regain it after stopping or slowing down. My mechanic is at a lost. David
