'74 9.9 issues

[shawnster8]

A couple years ago my grandfather gave me a '74 9.9 Seahorse, model # 10R74G. It hadn't run in about 15 years. My dad worked with it and got it running the summer after and I used it all last year. I never has run really great, always running a little rough and when you figure out all the quirks it's not a bad motor. My last river trip last year ended in a broken pull cord, lucky for me, it crank on that pull and I was able to get back to the ramp. Yesterday I put new plugs in it and checked the gear oil level (it was full) and set it up and a water tub and ran it for a while. Today I decide to head to the river, started right up and up the river I'm going when I started hearing some noise. First of all, at WOT it was about 50% and bogging really bad. I heard what sounded like bad wheel bearing on a car. It had that grinding sound and I could feel viberating through my 14' allum boat. I backed the throttle down and the motor shut off. I get over out of the current, tie up to a tree and begin to start the motor. It would not start after that. It would only fire up for a second or two and shut off. I tried pumping the bulb when it would be dying but nothing. I managed to float and paddle back down river and loading up and came back home. I tried many times to start it this evening with no luck. Any clue to what's going on? Thanks for any help at all.

Shawn

 

[4.0l sahara]

Re: '74 9.9 issues

It could be over heating is why it shut off. Ever replaced the impeller? I probally needs a carb cleaning and adjustment. Also tune up the ignition and might as well change the lu oil if it hasn't wasn't done. What fuel/oil ratio you running it at?

 

[OptsyEagle]

Re: '74 9.9 issues

Well, my 2 cents is that it sounds like at least one of your problems is that it is only running on one cylinder. Not only would this condition reduce your WOT power but would also add some vibration to the motor as well (although I am not sure it would lead to the vibration you are describing but then again, I am not sure I even know what you are describing).

There are a number of things you should do to determine this but here is an interesting observation that I had on my 1975 Evinrude, which if you do not know, is the identical motor. These motors specify champion spark plugs UL81C. I do not know what plugs you put in or what plugs you took out, but on my motor, when I put in Champion UL81C plugs, it would bog down and then surge and bog down again and eventually stall out and as you said, run not all that great at idle. I figured I was loosing a cylinder and then getting it back and then losing both and could not really figure out why. I verified that I had good solid spark from my ignition. I even tried a new set of UL81Cs to verify that I didn't put in some bum plugs (I had just changed them myself) with no difference. Now just before I did something really drastic I decided to change the plugs to some NGK B7HS (the cross reference plug for the UL81C) I had and presto, the problem went completely away.

It never came back all year but I didn't really believe that the Champion plugs wouldn't work on my motor so the next year I put in a whole new set of those Champions and again, same problem as above. Needless to say I now use the NGKs. I use Champions in other outboards I have with absolutely no problem, but those 1974 to 1976 9.9HP Johnson/Evinrudes do not seem to like them in my opinion.

Those are my observations and experiences.

 

[Solittle]

Re: '74 9.9 issues

Shawn - Do the basic troubleshooting stuff - compression - spark & fuel then let us know what you find.