115hp Johnson low power

[newtong_ware]

I have a '76 Johnson 115hp v4. Had it about 1 year and continue to have problems. Runs good sometimes, but most of the time it won't go over 5-6 mph. Cuts out and / or "surges" at full throttle. When it does run, it'll throw you out if you don't hold on!<br /><br />I have worked on fuel system and thought I had it when I repaired or replaced lines. New lines all the way from the tank now. Rebuilt the fuel pump and no help. Took the carbs apart and had a look, spotless.<br /><br />I am reasonably adept at mechanics and electric, but new to outboards, (and yes I'll be getting a manual real soon). Any suggestions? A quick and dirty comp check (with a pull rope) is about 85 to 90 on each cylinder with a cold motor.

 

[Dhadley]

Re: 115hp Johnson low power

Welcome!!<br /><br />Carbs that look spotless can still be clogged. Keep in mind that since the oil is in the fuel, if a cylinder isnt getting fuel it isnt getting oil.

 

[Solittle]

Re: 115hp Johnson low power

newtong - You need to rebuild the carbs. Follow the manual and you will have no problems. After you have soaked the disassembled carbs overnight blow out all passages with high pressure compressed air (not the rattle can stuff).

 

[newtong_ware]

Re: 115hp Johnson low power

Thanks guys, common sense says it has to be the carbs, but...<br /><br />One more question, I have had the carbs apart and blew them out with about 80psi from my compressor. But I've always been a bit afraid of the little metal plates that you pop out and then replace. I assume you hit them with a hammer and punch to seat them, any advice on this particular job?

 

[limacina]

Re: 115hp Johnson low power

Don't jump into the carbs quite yet. I assume you have an inhull fuel tank. Take a portable fuel tank with the fuel line and pull the quick disconnect off and plug the line into the motor in place of the main fuel line and take it for a test drive. If you still have issues, then attack the motor and carbs. <br />In my case, I found out there was a screen inside the pickup tube in the tank that was clogged. I returned 4 carb rebuild kits the next day and saved $80.<br />Other issues might be loose fittings causing vaccum leaks, vent to tank clogged, sometimes the checkvalve in the squeeze bulb fails closed.

 

[djzyla1980]

Re: 115hp Johnson low power

To answer your question about the welch plugs... I took a wooden spoon andle and tapped on the spoon end to push the new ones back in... one oe two slight wacks in the middle and they were in...<br /><br />Check for leaks and a bad fuel pickup... as Limacina states... then tackle the carbs..

 

[newtong_ware]

Re: 115hp Johnson low power

Thanks for the response guys.<br /><br />I have tried various tanks, new lines and bulbs.<br />I've tried to eliminate any leaks and such, so this one has me stumped. Will probably be something so simple I'll hate myself when I find it.<br /><br />Can anyone tell me for sure that I should not be looking at the coils and / or powerpack? If these aren't likely spots for this type of problem then I guess it is on to the carbs.. Thanks again.

 

[djzyla1980]

Re: 115hp Johnson low power

I recently just purchased a motor that had the exact syptoms. Ran like crap most of the time but when it ran good it ran like a raped ape. Pulled carbs off and cleaned... worked a bit more often. Finally gave in and tore them down again to soak and rebuild. After the rebuild on the carbs... no surging, no bogging, no rough starts, can just get in it and go...like I wanted from the begining. There easy to rebuild and well worth it. Just make sure you clean out all passages... which includes those dumb welch plugs... but like I said earlier.. there easy to put back in.<br /><br />Your burnin fuel, and all cylinders are firing...look towards the fuel... you've done all else.... what your going to spend in a power pak you can buy about 5 rebuild kits.....