Weak spark on 1973 20 Hp Johnson

[Mumbles]

RANDY SCHNEIDER wrote:

I may be all wet, but I thought the carbs on those had a plastic low speed needle jet seat. Im pretty sure I bought one from Ed for a 20 I had to work on a while back. Seems they can get smashed or crack. I had to use a straightened fish hook to snag it out. Its a distant memory, but I remember fising that bushing and gettting the plate flat again. Might be something,
Randy

These carbs have a small plastic bearing/seal deep inside them for the low speed needle. A new one will be included in a carb kit.

• This reply was modified 3 years, 8 months ago by Mumbles.
• This reply was modified 3 years, 8 months ago by Mumbles.

[Evinrude 25]

Hello,
I am back to the board again! after cleaning the carb and put it back. I could start it 2 times. It ran ok since I by passed the kill switch. I could not stop it by the choke. I had to unplug the spark plug cable of the first cylinder to kill the engine while the choke still engaged. The engine was not stopped right away. It was still ran for a couple seconds. I started it again and un-pluged the second cylinder spark plug. It stopped right away. Next day, I could not get it run. Both cylinder still had spark. Pull many, many times until I broke the recoil spring so I could not start it. The recoil spring broke at the end so I could be able to rivet it back but have not done yet. Try to figure out how to adjust it.

[fleetwin]

OK, you are losing me here. Are you saying the engine will not shut off when you press the stop button? What do you mean by “passed the kill switch”??
The engine may not shut off when you pull the choke because the choke is set up to release a bit when it starts so it won’t flood and stall.
I fear you are getting a bit confused….
I want to review your initial issue…I thought you said the engine was tough to start when cold, but ran OK once started…And started OK when hot.
I suggested you check to make sure the choke was closing fully while cranking, you reported pulling the carburetor apart….
Did you check to see if the choke was closing fully while cranking?
This choke linkage is a little complex…It was engineered so that the choke would pop open slightly once started so it won’t flood and stall easily. You will also notice that the choke linkage opens the carb butterfly a bit when engaged also to make cold starting a little easier… So, if the linkage is messed up causing the choke not to close fully while cranking, or if it is not opening the butterfly slightly when engaged, it will be tough to start cold….

[Evinrude 25]

I have by-passed the kill switch (remove the wire of the stop button from the coil) during the process to make sure that I have spark on both cylinders. I forgot to connect again so when I ran the motor. I could not stop it by pressing the stop button. So I tried to choke it in order to shut it down but it did not so I had to pull the spark plug wire.
Yes, it is very hard to start at cold start! Even though I had the choke fully closing. I saw the saw flood out sometime. I will review of what you said and check all the linkage.
Timing of the point also had been rechecked to make sure the point open when the flywheel mark lined up between two mark on the mag plate.I put the new driver coil in so the whole ignition system has completely new part and it has strong spark!

[fleetwin]

Did the stop switch work before you disconnected it? If so, I can’t imagine why it wouldn’t work now…I don’t think there is a way to connect it improperly, there would be no spark if you inadvertently connected the stop leads to the coil primary connections. It is easy enough to check the stop switch leads with an ohm meter…
Using an ohmmeter on the high scale, connect the leads to the disconnected stop switch leads….The meter should read infinity, nothing less…
Using an ohmmeter on the low scale, connect the leads to the disconnected stop switch leads with the stop button depressed….The meter should read near zero ohms.
You report there is good spark, and that you are holding the choke closed….
Is the throttle advance linkage hooked up to the choke? Are you advancing the throttle sufficiently?

[Evinrude 25]

Success! Check the kill switch as fleetwin above description, infinity reading when NO and 24 ohm when NC. I reconnected the kill switch with the circuit. Then check the choke plate when I pull the choke. A mistake found, the choke plate was not completely closed. The pivot bracket screw interfered with the mechanism! Since I did not tight enough. Then I readjusted the idle needle 2 turns out from. It ran with a couple pulls. Now I will put the lower unit together and test it on the water!
Thank everyone for the great help!
Note: just pick up 1966 20 hp Johnson for the next project! This one should be easy to work on since it has the same block but just coil and point. No low tension system as this one.
Here is the link on YouTube. Is it normal shaking when running at low RPM?
https://youtu.be/vxLWWUcHQdc

• This reply was modified 3 years, 8 months ago by Evinrude 25.

[Evinrude 25]

Success. I got it run!
https://youtu.be/vxLWWUcHQdc
Is it normal shaking at low speed?

[fleetwin]

OK, well first we must realize that adjusting the engine on a stand with no gearcase, doesn’t mean too much… You will have to readjust once the gearcase is back on with the boat in the water.
That being said, that engine sounds real nice to me, they will shake like that. Once you have the engine running on the boat, make sure it gets up to temperature also. Just check the upper side mounts to make sure they haven’t separated/broken.
One more thought. You have reported hard starting when cold, I am assuming you have been starting the engine with the gearcase off, am I correct? If so, the engine may be hard starting simply because of the lack of load placed on it by the gearcase and water pump…. Have you ever tried to start a rotary mower without the blade installed? Most of them won’t start, they need the blade installed/load to help carry the crank through full rotations….

[Evinrude 25]

I could the water leaking!
https://youtu.be/8WtkZDA8JK8

[fleetwin]

OK, needless to say I am wondering what the big flood is all about in the engine pan….
The sneezing or coughing is not an ignition miss, it is how these engines react to a lean fuel mix. Unfortunately, this is one of the newer engines that incorporates a recirculation system to eliminate the fuel dump… These engines will never idle as nicely as the older models, I feel the recirculation system causes uneven conditions between the two cylinders. Leaning the adjustment out for the smoothest idle usually results in a lean spit/cough. So, you usually have to richen it up a bit, sacrificing idle smoothness, to avoid the lean spit. This sometimes results in fouled plugs unfortunately. Again, it is extremely important to make sure these engines heat up sufficiently to minimize fouling, and for the best idle quality….

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