9.5 Johnson - Flooding?

Fast Pat

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Aug 4, 2008
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I recently rebuilt the carbeurator on my 1971 Johnson 9.5 hp. No directions, I just reassembled as before. Immediately noticed that the engine wouldn't top out, choke made it worse. After 30 minutes I was down to one cylinder then, lost both. I pulled the spark plugs and found significant build up on the top plug, while the bottom plug was wet. That night I put new plugs on the plug wires, pulled the rope and, got good consistent sparks from each. So, I think it is a fuel issue. Could the carb float be too high resulting in excess fuel in the carb? How far should the float be from the carb body when the float valve is closed?
 

Joe Reeves

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13,262
Re: 9.5 Johnson - Flooding?

(Carburetor Float Setting)
(J. Reeves)

With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.

When time permits, visit my store at: http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store
 

Fast Pat

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9
Re: 9.5 Johnson - Flooding?

I pulled the carb and reset the float as suggested. Reinstalled the carb, installed new spark plugs and, she cranked right up but, ran rough. I put her in the water and can tell that she's only running on one cylinder. I got home, pulled the spark plugs and the top plug looks good. The bottom plug is wet and doesn't look like it has been fired but, both plugs spark when I hold them to a ground and try to crank her. Could a failing power pack do this?
 

Joe Reeves

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13,262
Re: 9.5 Johnson - Flooding?

That engine has no powerpack. It has two each of Coils, Points, and Condensers under the flywheel.

With the s/plugs removed, rig a spark tester whereas you can set a 1/4" gap. The spark should jump that gap with a strong blue lightning like flame.... a real SNAP! What do you have.

No Tester? See the following:

(Spark Tester - Home Made)
(J. Reeves)

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:


..........X1..........X2

.................X..(grd)

..........X3..........X4

That wet plug......is it fuel or water? Do you have compression on both cylinders?

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
 

Fast Pat

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Joined
Aug 4, 2008
Messages
9
Re: 9.5 Johnson - Flooding?

It is fuel on the spark plug and the top of the piston appears wet.
 

Fast Pat

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Aug 4, 2008
Messages
9
Re: 9.5 Johnson - Electrical

Re: 9.5 Johnson - Electrical

I widened the gap on a spark plug to 1/4" and grounded it to the crankcase. I can get a 1/4" spark for the top cylinder but not the bottom. Should I replace the condenser or the coil? Remember, I do get a faint spark across a 0.030" gap for the bottom cylinder.
 

Joe Reeves

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Feb 24, 2002
Messages
13,262
Re: 9.5 Johnson - Electrical

Re: 9.5 Johnson - Electrical

Without actually being there, I have no idea what needs replacing or cleaning. Remove the flywheel so that you can inspect those components.

The coil and attached condenser/points closest to the back of the engine fires the bottom cylinder.
 
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