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1967 Johnson JH22C 3 HP run problems

S

StevenInNH

New member
I am trying to get a vintage 1967 Johnson JH22C running smoothly. Two years ago, this motor was running "like a top" and was smooth through all power ranges. Then a "friend" left an unstabilized ethanol fuel in the tank. I finally have it running again, but it's not smooth through it's entire range. At low speed I can use the "low speed" needle and throttle to get a very nice smooth low idle. It starts on one pull almost every time.

My problem comes when I try to transition to high speed - it smokes badly and runs rough. It will intermittently go to high speed, but then quickly slow down, and sometimes, it stalls. This is what has been done so far

* The original 1967 points and condenser were replaced two years ago during the original rebuild, and it ran well.
* The head gasket was replaced, and all head bolts have been properly torqued.
* Spark plugs have been replaced with new Champion J6C (823) gapped at .030 in.
* The carburetor has been rebuilt, with a new float, needle valve, valve seat, seals, plus the high and low speed packing.
* The original high-speed orifice was jammed in place and not removable. I suspected damage, so a new float bowl and new high speed orifice were purchased and installed.
* The original high speed jet was removed, cleaned separately, and re-installed.
* The fuel tank was rinsed and the fuel filter was removed & cleaned. Fuel flow is good.
* A new fuel line was installed.
* New ethanol-free fuel was added. I used a 50:1 fuel ratio as described in the SELOC Johnson/Evinrude Manual. As it was handy, I used my Husqvarna ethanol-free 50:1 two-cycle fuel that I run in my string trimmer. I assumed pre-mix would be more effective and more evenly mixed than what I could make.

After all this, the motor runs in the test tank. It starts on the first pull almost every time. It runs at "start speed" smoothly, allows the rundown to low idle (I performed a successful slow speed needle valve adjustment). The high speed orifice and jet are fixed on this model - no adjustment can be made to the high speed, but it will not run smoothly or at full speed.

What am I missing?
*Is the fuel/oil ratio the culprit? I have a sneaking suspicion that my fuel/oil ratio is wrong. On another forum thread here, someone said the proper mixture for my engine was 30:1.
*Could it be the reed valve from the carb to the crankcase?

I just don't understand why it runs well at low speed but not high speed.
Any help is appreciated!!
 
Last edited:
It sure is hard to diagnose something like that when you have already rebuilt or replaced everything but the prop nut. Nevertheless, my first guess is a partially clogged fuel filter in the gas tank not allowing enough fuel flow to keep it going at high speed.

Otherwise, running on one cylinder???

BTW, 50:1 is correct, but saying that is like stirring up a hornet's nest.

It sure ain't the reeds.
 
fdrgator said:
It sure is hard to diagnose something like that when you have already rebuilt or replaced everything but the prop nut. Nevertheless, my first guess is a partially clogged fuel filter in the gas tank not allowing enough fuel flow to keep it going at high speed.

Otherwise, running on one cylinder???

BTW, 50:1 is correct, but saying that is like stirring up a hornet's nest.

It sure ain't the reeds.
Click to expand...


Thank you for the feedback. I'll order a new fuel filter next. Could it POSSIBLY be the points or condenser? They were new a few years ago and worked fine. Plug wires were new then as well. I doubt they would have failed in two or three years? Would that engine run on one cylinder at all? Although if one cylinder wasn't burning the fuel, it might explain all the smoke...
 
Start from the beginning what are your compression numbers? Does the spark jump a 1/4 open air gap? If both are good then it is a fuel supply issue or possibly a engine sync issue? Does the carb just begin to open as the line on the throttle cam passes center of the follower roller?
 
kimcrwbr1 said:
Start from the beginning what are your compression numbers? Does the spark jump a 1/4 open air gap? If both are good then it is a fuel supply issue or possibly a engine sync issue? Does the carb just begin to open as the line on the throttle cam passes center of the follower roller?
Click to expand...

I suppose I ignored a lot of that, since it was running perfectly before the fuel got left in it for almost 2 seasons... I never removed the carb from the block, so the original cam/throttle settings should have been where they were when it was working well. I can check the carb/throttle cam sync and spark gap jump fairly easily. Compression testing is harder since I don't own the equipment. I'll have to borrow some.
Thank you for the advice!
 
fdrgator said:
Yes, ​they will run very well on one cylinder. Just no power. And yes, it could be the points. Stuff corrodes.
Click to expand...

Hmm... The motor WAS stored in an exterior shed, and it WAS exposed to changes and temperature and there was some condensation rust on tools in the shed. Perhaps this is part of the problem. It's an easy fix too.
Thanks for the input!
 
kimcrwbr1 said:
Have you tried running it without the silencer?
Click to expand...

I have checked the silencer - it's clean. The vent hole on the front of the carb is clear, and I cleaned the screen. I did all that when I rebuilt the carb. I'm leaning towards points at this moment... It would explain rough running and partial combustion (plus it's easy to fix)
 
The rubbing block on the points must be lubricated or it will quickly wear down and the point gap will quickly decrease to the point that they no longer open. If there is any rust on the cam itself, this will happen very quickly. You didn't mention if the coils were new...that could be another source of trouble. Do you know that both cylinders are contributing??? After shutting it down, the cylinder head temperatures should be the same on both cylinders. ( you can do this by simply using your hand to feel for any difference in temperature ) Are there any swimming pool chemicals stored in the shed...Chlorine containers, regardless of how tightly they are sealed, can cause items stored in the shed to rust prematurely. The Air cooled Husqvarna fuel mix is okay for emergency use but probably does not have the TCW (two cycle water cooled) designation you need for outboards. The fuel filter is sintered brass and screws into the bottom of the fuel tank. I have had success cleaning it by "back washing" it with a spray can of Walmart carburetor cleaner. These are great motors...especially with the shallow water, "weedless" lower unit.
 
I've not opened the top to see if there is rust on the cam or on the points - however it was stored in an exterior shed. The tools in the shed all have a fine layer of rust caused by condensation that occurs in the spring when the cold shed contents hit the warm, moist spring air. It is entirely possible that there is rust there. I will check. After all, the points are inexpensive and easy to replace. As for the coil, it was original, but when this machine ran two years ago, it ran like a top with no lack of spark, so I suspect the coil is OK. Also, there is no chlorine (or any other chemical that becomes corrosive on contact with water) stored in the shed.

I have pulled and back washed the fuel filter with carb cleaner already. There is good flow from the filter into the carb, so I don't suspect that's still a problem. I may replace it if I'm already buying new points. It's another inexpensive and easy fix.

I had NO idea that the 2-cycle oil was specific to water cooled engines with a TCW designation. I assumed the premix was more accurate than what I'd mix and would have been better. I have Johnson specific oil. I'll make my own 50:1 with that and ethanol free fuel.

Finally - I am a science teacher and happen to have a FLIR Infrared camera, so I can look at the head temps directly. I should be able to tell if they're both firing evenly. That's a really great idea that I'd not thought of.

Thank you for all the input.
 
bobbyc said:
The rubbing block on the points must be lubricated or it will quickly wear down and the point gap will quickly decrease to the point that they no longer open. If there is any rust on the cam itself, this will happen very quickly. You didn't mention if the coils were new...that could be another source of trouble. Do you know that both cylinders are contributing??? After shutting it down, the cylinder head temperatures should be the same on both cylinders. ( you can do this by simply using your hand to feel for any difference in temperature ) Are there any swimming pool chemicals stored in the shed...Chlorine containers, regardless of how tightly they are sealed, can cause items stored in the shed to rust prematurely. The Air cooled Husqvarna fuel mix is okay for emergency use but probably does not have the TCW (two cycle water cooled) designation you need for outboards. The fuel filter is sintered brass and screws into the bottom of the fuel tank. I have had success cleaning it by "back washing" it with a spray can of Walmart carburetor cleaner. These are great motors...especially with the shallow water, "weedless" lower unit.
Click to expand...

I've not opened the top to see if there is rust on the cam or on the points - however it was stored in an exterior shed. The tools in the shed all have a fine layer of rust caused by condensation that occurs in the spring when the cold shed contents hit the warm, moist spring air. It is entirely possible that there is rust there. I will check. After all, the points are inexpensive and easy to replace. As for the coil, it was original, but when this machine ran two years ago, it ran like a top with no lack of spark, so I suspect the coil is OK. Also, there is no chlorine (or any other chemical that becomes corrosive on contact with water) stored in the shed.

I have pulled and back washed the fuel filter with carb cleaner already. There is good flow from the filter into the carb, so I don't suspect that's still a problem. I may replace it if I'm already buying new points. It's another inexpensive and easy fix.

I had NO idea that the 2-cycle oil was specific to water cooled engines with a TCW designation. I assumed the premix was more accurate than what I'd mix and would have been better. I have Johnson specific oil. I'll make my own 50:1 with that and ethanol free fuel.

Finally - I am a science teacher and happen to have a FLIR Infrared camera, so I can look at the head temps directly. I should be able to tell if they're both firing evenly. That's a really great idea that I'd not thought of.

Thank you for all the input.
 
Don't lose sleep over the water/air cooled oil differences. It has mostly to do with the detergents and the temp to make them behave. Air cooled engines can run much hotter. Needless to say, you want TCW-3 to prevent carbon deposits.
 
FYI you can get an inexpensive compression tester on Amazon. I have this one that only cost $20.78. It's a good quality for the price. Free shipping with Prime.
https://www.amazon.com/gp/product/B000EVU89I/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

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I cleaned the carb on my 3hp Johnson back in the spring using Berryman Chem-Dip along with spray carb clean and compressed air. I finally ended up cleaning it again using my ultrasonic cleaner. The expansion plug should be removed to clean in that area also. A new expansion plug is included in the carb kits. The second cleaning did the trick.

lThT5fB.jpg
 
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