'72 Johnson 100hp Cuts Out

jhetrick55

Petty Officer 3rd Class
Joined
Apr 21, 2017
Messages
83
Last time I had my '72 Glastron Swinger with '72 100hp Johnson out, trying to pull a tube with a young teenager on it, the engine died every time I tried to accelerate. I cannot figure out why this might be. I do have a suspicion the clutch dog needs to be done, but I don't think that would kill the engine. The engine seems to run fine not pulling anything.

Any thoughts as to what I should look for with this engine dying while trying to pull something small like that?
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
You should do a spark test on every cylinder and also a compression test too.
Add a drop test to the test list as well.
Also just taking out your sparkplugs and comparing them may tell you whats up and locate it down to one cylinder
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Sticky timer base. Dis-connect throttle cable at engine (not running). Now put your fingers on the lever where the cable was connected and push it to the rear, watching what happens at the upper end (timer base), and the carburetor throttle shafts. The carb shafts should open very little until the timer base goes all the way to the rubber stop bumper. Only after the timer is at full advance, should the carbs fully open. If they open before full advance, it will stumble and probably conk out and stall.

If this is a good guess, the timer base needs to be removed, cleaned and re-lubed. While doing that, you will see a silver wire anti-reverse spring on the crankshaft. If it has been neglected, it is over due for service anyway. That spring is to be cleaned and very sparingly re-lubed with some EP grease as regular maintenance.
 

jhetrick55

Petty Officer 3rd Class
Joined
Apr 21, 2017
Messages
83
Thanks for these suggestions. I will check both of these things out and do any maintenance I need done. Unfortunately, because I live in Minnesota I won't fully know the results until spring. Much appreciated!
 
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