1975 Evinrude/Johnson 115hp preformance question

[Jackle75]

I have an 1975 Evinrude 115HP Model# 85593E on an 1988 Cajun Fireo Classic 16ft. Recently, the engine started to sneeze or cough. In other words, as I'm boating along it acts as if it wants to cutoff. I recently replaced two of the ingintion coils and replaced the spark plugs. I took it to a mechanic and they completed a power tune, whatever that means. The problem really got worst this past saturday while out on the lake. I don't have a problem starting the boat, it starts everytime. Can anyone provide me with any items to check, a DIY project. I don't have any outboard experience but I recently purchased a manual for the motor yesterday and I have begun to read it. Any advise would be helpful. Thanks.

 

[MRneatfreak]

Re: 1975 Evinrude/Johnson 115hp preformance question

Sounds like it could be any number of items. Since you recently messed around with spark I would double check to make sure your plugs are gapped correctly. Should be .030" correct me if am wrong. Also make sure your plug wires are not touching eachother, the block, and that they are securely fastened to the top of the plugs. Also could be fuel issues. Do you have a fuel/water seperator? When was the last time you dumped it out?

 

[emdsapmgr]

Re: 1975 Evinrude/Johnson 115hp preformance question

A periodic cough (at idle only) could be a lean sneeze. This is a carb problem-not ignition. Probably debris (dried fuel) in the small idle passages of the upper carb body. This problem is usually at idle only-once you crack the throttle even a little-the other (high speed jets) will take over and supply fuel-it may run fine at WOT.

 

[Jackle75]

Re: 1975 Evinrude/Johnson 115hp preformance question

The problem happens with the throttle wide open. I have noticed a sneeze during idle when I have the water hose connected. Fuel could also be the problem. I'm not sure if I have a fuel/water separator. How can I tell if I have one?

 

[MRneatfreak]

Re: 1975 Evinrude/Johnson 115hp preformance question

You would know it if you had one. Just follow the fuel line from the fuel tank to the motor. If there is not a spin on filter on a metal bracket anywhere then you don't have one. I would drain the fuel bowls on the carbs first. Make sure you prime the fuel bulb a couple times to flush any water or debris trapped in the high speed/drain screws. It probably wouldn't hurt to take a peek at the carbs if after draining them doesn't help the problem.