1975 70hp johnson stalling out

[jor593]

i have a 1975 70hp johnson that was running extremely rough. i replaced the plugs and its running great now but it is still stalling out when im at low rpm's any suggestions? im thinking maybe carbs and in that case what do i do about them?

 

[Big Bubba]

Re: 1975 70hp johnson stalling out

Jor593,
Yes, I would highly rebuild your carbs with brand new rebuild kits. When was the last time the carbs were rebuilt? If they haven't been rebuild I would do that now becuase your low/idle speed jets and passageways are probably clogged up. Also, when was the last time you replaced your waterpump impellar? If that hasn't been done do that also. The way I look at it is if you do the preventive maintenance now which is alot cheaper than a total rebuild becuase you didn't do the basic maintenance on it. Also, I would change out the lower leg unit gear lube and make sure you get new o-rings for both the upper and lower drain/vent screw. Take care, Bob

 

[jor593]

Re: 1975 70hp johnson stalling out

i guess i should of added this originally the motor has been sitting in a barn since 1992 i just put it on a 17ft fiberglass boat 4 weeks ago i replaced the plugs the gear lube and the rectifier i planned on doing the impeller this winter. so i figured something needed to be done about the carbs but i dont know much about boats and em not sure about tearing into the carbs

 

[Big Bubba]

Re: 1975 70hp johnson stalling out

Jor593,
Those carbs are easy to do. Just don't disturb the linkage adjustments when you remove the carbs for rebuild. In my honest I would buy the genuine Johnson/Evinrude carb kits for your outboard becuase they are better than the aftermarket ones and for me I don't want to have to take these carbs off again to rebuild them. Usually the carb kits have instructions inside of them that is easy to follow. I would remove your jets, one at a time, so you don't miss-match jets from different areas since you have three jets inside your carb. Use compresssed air and get yourself a can of carb cleaner to blow through the passageways where the jets go and then blow throw them with compressed air and put those jets back in. Let us know how it turns out. Bob

 

[Big Bubba]

Re: 1975 70hp johnson stalling out

I would also add that I would flush the heck out of that fuel tank if it has been sitting since 1992 inside a barn and get yourself a good fuel line with the primer bulb get the Johnson/Evinrude since it is better than the aftermarket again in my honest opinion.