1993 Johnson 9.9 lower cylinder wet.

[Abefish0]

Hello,
I recently bought a 1993 Johnson 9.9 2 stroke outboard. It was sitting for close to 20 years but the previous owner ran it out of gas before putting it away in a barn. He claims that it was only ran 3 times and it looks brand new under the cover. When I hooked up a fresh tank of gas it ran flawlessly. After that I had it out around 5 days and it was running perfectly. Last week when I had it out it started running very rough throughout the entire RPM range. I got home and took the spark plugs out. The top plug looked perfect but the bottom was very wet. I checked compression and I have 110 PSI in both cylinders. I checked my spark with an inline spark tester and the spark is extremely strong. The carburetor is very clean and fuel pump is working as it should. I replaced my spark plugs just to be sure and had no changes but when I unplug the bottom spark plug wire it doesn’t change how it runs but when I unplug the top plug the motor stops so it is only running on the top cylinder. Any pointers or advice would be very helpful and appreciated.
Thanks.

 

[Mc Tool]

Swap the plugs over and see if the fault follows .....might just be a duff plug

 

[saltchuckmatt]

Did you replace the impeller? A motor that's sits that long is bound to have cracked rubber.

Swap coils, ohm everything out and if it test ok, replace power pack.

Doesn't sound like it has the "Good" spark. Do a spark GAP test. 3/8 with a bluish crack. Gap testers are $15 at any auto parts store.

 

[Abefish0]

Thanks,
I did a spark gap test and both measured above 3/8’’. I also swapped top and bottom plugs and had no difference.

 

[racerone]

Fuel pump diaphragm?----Easy to check and easy to fix if ruptured.

 

[Abefish0]

I appreciate the help. When I take the fuel pump off of the engine and squeeze the primer bulb, gas leaks out the sides but not the back of the pump. When it’s bolted to the engine it doesn’t leak out of the sides.
Any advice on how else to check if that’s my issue?
Thanks

 

[tphoyt]

You will need to take the pump apart to inspect the diaphragm. You would be looking for tears or even a very small pinhole. No fuel should come out of the hole in the back. That hole is for the pulse that operates the pump. If the diaphragm has a hole it will deliver to much fuel
If it were me on an older motor I would just rebuild the pump regardless.
Best

 

[racerone]

Broken reed valve perhaps?

 

[Abefish0]

Thanks for all of the suggestions, before I take apart the fuel pump. Wouldn’t the needle/seat and float regulate to total amount of fuel being let into the engine keeping it from flooding? Or can a failed fuel pump cause too much fuel to be let into the lower cylinder.
Thanks

 

[saltchuckmatt]

Thanks for all of the suggestions, before I take apart the fuel pump. Wouldn’t the needle/seat and float regulate to total amount of fuel being let into the engine keeping it from flooding? Or can a failed fuel pump cause too much fuel to be let into the lower cylinder.
Thanks

Fuel pump rupture will allow fuel to spill into the crankcase causing an undetermined amount of total 2 stroke mayhem and you might even need a outboard whisperer. Lol....take it apart, it easy. Remember, if you have spark...and good spark, compression...good compression then it has to be fuel. If you had more than one carb, then your theory could apply.

 

[tphoyt]

Yeah I forgot you mentioned it was the bottom cylinder that was wet. Racer mentioned reeds and I guess if there was a broken or bent reed and there was a bad diaphragm dumping extra fuel in the top it could possibly be getting sucked into the lower cylinder. I have never seen that but it sound plausible. I’m sure I will be told if it’s not.