3hp Johnson won't run

[Oberlieutenant]

Okay, here's what I've done:

• Drained gas
• Cleaned carb with solvent and air
• Changed plugs

The motor sat for a few years, so there was a significant amount of varnish in the carb, but I'm certain I got it all.

If I shot a little ether in to the silencer, it would fire and then die. One of the cylinders has weak/no spark - but when I removed the plug, the other cylinder would again fire and die, with no ether.

Does this sound like a gas issue or a spark issue to you guys?

I really don't want to take it someplace to have it repaired, when so many parts are readily available.

 

[Xcusme]

Re: 3hp Johnson won't run

OK, unless you want to destroy your motor, stop using starter fluid, there's no lubrication in the spray you'll damage the cylinders. Use a spray bottle with fuel mix instead.

You're probably going to want to remove the flywheel (use harmonic balance type puller) and inspect the coils for any cracks, replace coils that are cracked. Inspect points, set point gap to .020.

You didn't post the model number, so we don't know if your motor has the built-in tank or a remote fuel tank. If it the integral tank, remove fuel hose at carb and open fuel shut-off valve, fuel should flow smoothly. If not, inspect tank, paying attention to filter screen at bottom of tank for debris.

 

[Oberlieutenant]

Re: 3hp Johnson won't run

OK, unless you want to destroy your motor, stop using starter fluid, there's no lubrication in the spray you'll damage the cylinders. Use a spray bottle with fuel mix instead.

You're probably going to want to remove the flywheel (use harmonic balance type puller) and inspect the coils for any cracks, replace coils that are cracked. Inspect points, set point gap to .020.

Roger that. I dun wanna ruin this one because it's the only one I can afford.

Thanks for the advice.

 

[Xcusme]

Re: 3hp Johnson won't run

Those OMC twins are fine running motors if cared for. Parts are readily available and cheap. Get her hitting on both spark wires, then move onto the fuel issue (if there is one). The water pump impeller is a must do item. More motors are destroyed from overheating more than just about any other reason, beside running too lean.
Good luck, and report back with what you find.

 

[Oberlieutenant]

Re: 3hp Johnson won't run

Those OMC twins are fine running motors if cared for. Parts are readily available and cheap. Get her hitting on both spark wires, then move onto the fuel issue (if there is one). The water pump impeller is a must do item. More motors are destroyed from overheating more than just about any other reason, beside running too lean.
Good luck, and report back with what you find.

Roger that! Excuse the stupid question, but where is the impeller housing?

 

[JB]

Re: 3hp Johnson won't run

Inexperienced people cleaning carbs on outboards are a lot like little boys washing behind their ears, Ober. This is particularly true on the little ones.

We need the model number. They made those little jewels for over 60 years and they are not all the same. You will need that to get the correct carb rebuild/overhaul kit.

There are up to three very tiny passages into the carb throat. I have found these plugged with varnish on uncountable "just cleaned" carbs. You will need a carb rebuild kit with the welsh plugs to replace those on top of the carb body. Remove those plugs to get access to the the tiny passages into the throat (I drill them and pop them out with a small punch) and physically clean those tiny passages with jeweler's drills or stiff wire. Then put the new plugs in.

 

[Oberlieutenant]

Re: 3hp Johnson won't run

Inexperienced people cleaning carbs on outboards are a lot like little boys washing behind their ears, Ober. This is particularly true on the little ones.

We need the model number. They made those little jewels for over 60 years and they are not all the same. You will need that to get the correct carb rebuild/overhaul kit.

There are up to three very tiny passages into the carb throat. I have found these plugged with varnish on uncountable "just cleaned" carbs. You will need a carb rebuild kit with the welsh plugs to replace those on top of the carb body. Remove those plugs to get access to the the tiny passages into the throat (I drill them and pop them out with a small punch) and physically clean those tiny passages with jeweler's drills or stiff wire. Then put the new plugs in.

It's a 1963 JW-18R. I appreciate the assistance. I cut my teeth on small 2-and-4 stroke engines, but it certainly seems like there are there a lot of particular nuances to outboards.

 

[Oberlieutenant]

Re: 3hp Johnson won't run

OK, I *think* I have the problem sorted out - the coils and plug wires were corroded - one significantly worse than the other. Have parts on order (including a carb rebuild kit) so I am gonna re-rebuild the carb, replace the coils, plug wires, condensers and points and see what happens then.

 

[Xcusme]

Re: 3hp Johnson won't run

Roger that! Excuse the stupid question, but where is the impeller housing?

There are no stupid questions....how are you going to know without asking?....

Anyway, here's a pic of the lower unit for a 1968 3hp Johnson.It's not your year, but you'll get the idea. To replace the water pump impeller, you'd remove 4 bolts (#33) and the lower unit should drop down. Part # 7 is the impeller, part # 4 is the impeller housing, part # 8 is the impeller drive pin. Full pump repair kits are available and include all parts necessary.