What should I look for before purchasing this Johnson 9.9 HP outboard?

tomhath

Master Chief Petty Officer
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Dec 5, 2007
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814
while the guy Im dealing with did the work on the motor to get it up to speed, he has to communicate with the owner about what Im offering, then get back to me. . . That might mean driving 2 hrs out there, not liking what I see and giving a lower offer, then having to come back after the po makes a decision. . .

The guy doing the sellling should know what price the PO will accept. It sounds to me like he's trying to stall on accepting an offer in order to try and get a couple on the table so he can negotiate harder. I'd make a "take it or leave it" offer and make it clear that you won't drive out a second time; clear it with the PO on the phone right then or no deal.
 

poida

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Jan 24, 2009
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F_R what were the kits to fix these motor's (pre 77's) ?

And what was the fix? A cdi ignition?

I have an oldie with a newer power head, points and condensor's and it runs a treat. I know something has been swapped from another motor because i don't have the timing marks to check the points against. (on the armiture i think).

I use it to putter about in the shallows as it sits higher than my 30hp and slow speed trolling (both of which should cause the plug fowl condition) for spearing)
 

F_R

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Jul 7, 2006
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There were several kits, and I don't remember the exact details of each. Safe to say they replaced the cylinder head with one, the carburetor with another, the armature plate/mounting parts with another. A couple were just dumb stuff like telling us to check the operating temp.

Your armature plate should have timing marks. But I believe they are in the form of a curved scoop in the rim of the plate, instead of the conventional two lines.
 

racerone

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Dec 28, 2013
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There is nothing bad about having to use a bit of starter fluid for the first start of the day.--There is lots of oil coating the parts from when it ran last !!!
 

tomhath

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Dec 5, 2007
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814
F_R what were the kits to fix these motor's (pre 77's) ?

And what was the fix? A cdi ignition?
...

Leroy's Ramblings has some discussion of the problem. As I recall, he thought the problem was that the fuel wasn't being vaporized properly; raw fuel would hit the plugs and cause the fouling. Turning the open side of the spark plug toward the exhaust seemed to help some; eventually they modified the piston to give better flow. That plus the hotter spark from the cdi ignition seemed to help. He also suggests no more oil than 50:1 for normal use and even less for trolling.
 

jaymen1957

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Jan 27, 2015
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You asked about 9.9 OMC engines, here is my comment as I have owned several since 1978:

Well, despite all the comments to the contrary,
I have a 1975 Johnson 9.9, with a 15hp carb, and it runs like a champ. I use it to troll, it ticks over like a clock, idles smoothly, starts first pull. Has plenty of torque, will plane a 12 foot boat with three adults in it at 6800 feet of elevation, and since I have owned it (1980) it has been faithful for every season and never left me stranded out on the lake. Prior to putting on the 15 carb, it ran great as well, but the 15 carb helped it with some more power, especially at altitude. The engine sits in a barn under snow for 7 months a year, and always starts right up. In 2011, I replaced the fuel pump and fuel lines, re-sealed the lower unit, and replaced the powerhead with a used one off a 1975 Evinrude 15. The difference was amazing, even more power, and a much smoother idle and trolling. It also now gets much better fuel economy. The reason I put on a new powerhead was because in 1982, I took the head off to inspect the cylinders and saw severe scoring from a previous seizure that was due to the thermostat corroding closed, as the prior owner ran it in salt water on his skiff and never flushed it. Despite the damage, I ran this engine hard for the next 29 years and it never gave me any trouble...good old bulletproof OMC, made in USA, never say die!

In all the years I have owned this engine, I set the points twice, and both times they were within tolerance, but I like to have them perfect. My engine ignition coils developed minor cracks over time, but they still work great and throw a fat blue spark. If fact, you can put your palm on the flywheel, and turn the flywheel, and she will often fire right up!!

One trick I learned with this engine is to run B7HS plugs instead of the colder B8HS plugs that are specified. It is common knowledge that these engines will foul the standard plug, especially if you troll or run low speed all the time, and you are in colder climates. All the marina operators at my lake equipped their 9.9 rental fleet engines with one stage hotter plug. Another problem is that the thermostat can stick open, or it's seal can leak, and over cool the engine, which will foul plugs, so be sure the engine block gets hot enough that it is uncomfortable to touch for more than 5 seconds.

Another piece of common sense is that you need to slightly lean out the low speed mixture for trolling and low speed, and open it a 1/4 turn for cold starts. Now, if someone does not know enough to use the low speed mixture adjustment(its there for a reason) and you don't run a hotter plug, well it's your own fault if the engine acts up and you can't figure it out.

There was an earlier cylinder head with 7 bolts on the thermostat cover instead of 8. There was a change made that re-routes the water circulation in the head for more even temperature, that is the 8 bolt version that came as part of the warranty retro-fit kit by OMC. Both of my 1975 powerheads came with 8 bolts thermostat covers however.

By contrast, I had a 1982 Johnson 9.9 with electronic/CDI ignition and had nothing but problems with the ignition system; it blew out two CDIs, had problems with the throttle linkage sticking, and the plastic parts like the transom clamp levers eventually cracked and broke, as did the cam for the carb on the mag plate. I sold this engine as it was problematic and nowhere as reliable as my 1975.

One thing I do know, and that is to avoid the plastic top carbs that came on the later versions of the 9.9 and 15, as the warp and leak...see Leroys ramblings for more details.

So, despite all the naysayers here, as a longtime owner of one of the early 9.9 engines, I have nothing but praise for them and will never sell mine.
 

Acton

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Jan 15, 2015
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So I ended up buying the 78 9.9 shortshaft evinrude with a 15hp carb with gas tank and fuel line for $500 today! It was a cold day but I was able to get her started on the first pull! Idles real good, runs well both at slow and fast speeds. Lower unit looks to be in great condition, water flow is great and PO replaced water pump and gave proof by showing receipt for new pump kit and showed me old impeller. Compression is 90psi on both cylinders! Oil in lower unit is normal color with no creamy white coloring. Fuel lines look great and dont feel hard. Looking forward to getting out on the water with her this summer! Pictures and videos to follow! Thank you everyone for the advice!
 
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nwcove

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May 16, 2011
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congrats Acton! spend some time reading leeroys ramblings, its a great resource!!
 
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