Re: 1974 Evinrude 9.9 won’t idle at low RPMs, need help

[joesnuffy]

I am glad I cam across this thread and am glad I found this antique outboard engine forum. Thanks to all who are responsible. I own several antique outboards and have done so for the past 30 years I am in no way an expert but not a beginner either. I wan’t to post what I have encountered on these particular 9.9hp’s. I have seen a lot of things in this thread I want to check out next winter on my 9.9hp’s which are located in Key West. I don’t know if any of this will help but thought I would share my experience with these engines.

I own 3 of these 9.9hp engines . My runners are a 1991 and one is a 1976 with a 1987 being for parts all 3 enginnes were given to me last winter in Key West while I was wintering/camping on a Navy Base. I repaired 2 of them for a 11 foot boston whaler I purchased and wanted 2 runners one for a back up and one for normal my regular runner. I am pretty good at fine tuning carbs on vintage outboards but always learning. My 1991 is technically a 15hp but the only difference I can find is the carb on it mainly the high speed jet and possibly the throat size. The power head piston size and strokes look the same on all 3 engines regardless of the years they were built.

The 1976 has points and the 1991 has a cdi. The carbs are also different on the 2 out of the 3 engines. The 1976 and 1987 has essentially the same carb the 1991 has a different style carb with a needle valve retainer I don’t see a needle seat bearing on that carb like I do the 1976 carb

http://www.marineengine.com/parts/johns … Carburetor

To cut through the chase I had one heck of a time getting them to idle as they should. I fined tuned the carbs the best I could, rebuilt the fuel pumps, new plug wires and caps, new wires also and new fuel lines and cleaned the carbs.

What I found strange about the carbs is one the 1991 I had to pull the choke out 1/4 inch and it would idle done like normal and keep on idling. On the 1976 I had to pull the choke out 1/2 inch and it also would idle down and idle as it should. I mainly ran the 1991 15hp when out on the boat and after it ran for like 1 hour just above idle speed I could then push in the choke that 1/4 inch and it would idle normally also. I never ran the 1976 that long I used it for my back up motor. I guess what I find strange about it is the ignitions are different, carbs different, fuel pumps the same but the both had the same type of issue. I pulled the carbs down a couple of times but once I got them running correct I just have learned to live with it. I do want to tear the carbs down again now I have found this thread to see if I can get that quirk out of them. I forgot to mention I was running new NGK plugs in one and Champions in the other so not sure if it’s a plug issue wouldn’t think so they always look clean after I run them for a while on the water at just above idle speed.

I do have a like a 1968 Johnson 9.5hp I totally rebuilt even added the elctronic modules to it and got rid of the points. I also re-did a buddies 1965 Johnson 9.5hp that was his grandfathers never had this type of issue with those carbs.

Sorry to be so long winded.

Take Care,
Joe

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