1963 40hp johnson running on one cylinder

[Lake time]

Ok I have run out of ideas I have a 1963 40 hp Johnson super sea horse elictric shift only running on one cylinder. It's running on the bottom cycling the compression in the motor is good it's about 110psi per cylinder I've put new points condensers plugs boots wires on it and it's still running on one cylinder. I was wondering if maybe the cut off switch has something to with it kicking out the one cylinder. I get hot water out of the exhaust. When I took it out on the lake it fires up fine till it gets warm then won't start again for 10 or so minutes. Still running on one cylinder? Carb was rebuilt and new reeds. What am I missing? Somebody please help me with this before I shoot it!

 

[Tim Frank]

Coils.

 

[Lake time]

Brand new they have about 20 min run time on me it didn't change anything

 

[Lake time]

Em not me

 

[Lake time]

Is ther anything else I sho look at

 

[Tim Frank]

OK.
Coils weren't on your list.
How did you confirm that it is running on one cylinder?

 

[Lake time]

Yeah sorry lol plug in the top cylinder is always wet where the bottom plug is always dry and brown and I'm getting a lot un burnt fuel/oil in the water in a bucket or on the water bottom cycled has a nice bright blue snap of a spark where the top plug is blue but not as strong as the bottom spark and on the water it only gets me to about 10 mph when the I wou do 24 with her last year it's on a 14" mfg runabout

 

[racerone]

Check fuel pump diaphragm.

 

[Lake time]

Why would the fuel pump alow it to only alow one cylinder to run but not the other

 

[racerone]

Simple---If the fuel pump diaphragm is ruptured it would flood one cylinder with fuel and motor would not run properly.--This advice is based on some 40 years experience with these motors !

 

[Lake time]

Ok I'll take a peek tomorrow

 

[achris]

Fuel pump is run by the bottom cylinder. If it was flooding a cylinder, it would be the bottom one, not the top....

LT, check the top crankshaft seal. Seen that problem plenty of times... Compressions shows good, runs for a little bit before the seal warms up and leaks...

 

[Tim Frank]

Do a cylinder drop-test to confirm.
With the engine running, pull one plug boot at a time off its plug.

You have not really provided much info.
Did you just acquire this motor or have you had it a while....which leads to ....is this a new problem or has it never run properly for you?

Do you have a manual? If not, how much experience have you had with the ignition on these? i.e. is it running better or worse since you have been wrenching on it?

What type of plug wire did you use.....copper core?

Make sure that both ends of the wires are properly and securely put together.... in the coil sleeve and the plug boot clip. The wire screws onto a threaded post in the coil, not just pushed in and cross fingers.

 

[Lake time]

Yeah she used to run like a top I used to water ski behind it I have quite a bit experience with that type of ignition system I have an engine repair shop I started out with small engines now I'm a ase master diesel tech. I know boat motors are different than diesel engine but I'm really familiar with the old 4 stroke tuhcumsa engine which has the same ignition systems I have done a cylinder drop test she starts up fine with the bottom plug boot on but when I pull the bottom one off and put the top one on it doesn't even attempt too run I'm getting 100 psi in each cylinder on a compression test just for a look I pulled the head off to have a look it still has the hone marks in the cylinders I got the motor early this year after it sitting for 10 years I re built the lower unit carbs new points condeners reeds water pump she ran fine up to a moth ago I'm at a loss the only things I didn't do was fuel pump or the vacuum kill switch

 

[Tim Frank]

Check the spark with a proper spark tester....the spark should jump 1/4" gap.
That will all but eliminate spark/ignition as the issue.

If the top cylinder does not generate that healthy spark, that is where you need to focus.
From a distance I'd suspect point gap and cleanliness.

 

[Lake time]

Yeah new spark plugs and the top still isn't getting that bright blue snap of a spark like the bottom i am really appreciate ing the help so far