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Johnson motor shuts down

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Vlad22

New member
Hello everybody,

I just registered to the forum, but have been reading it for a few months. Great place to find a lot of useful information.

I have a 1999 2 stroke 70 hp 3 cylinder Johnson motor. It starts well and does the first run without any issues. Then, very shortly after you restart it, it starts loosing power and shuts down. After that it is not possible to restart it for almost an hour. Then, the motor will restart, but will loose power and shut down quickly.

Brought the boat to the mechanic and they said they had it fixed. Picked up the boat, launched and got the same issue immediately.

Would anyone have an idea what is going on there?


Thank you very much for any advice you may have!

Vlad
 
Gotta be spark. Can you check spark when it dies out and see what's happening? If the spark comes back when it cools down then we will start a focused diagnostics. Often times it will lead us to a stator or power pack.
 
Usual problem:
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Meltdown of stator (under flywheel) Check it closely visually to see if there is a sticky looking substance dripping from it down on the powerhead & timer-base. If so, replace it.

Stators eventually fail in this manner due to the overheated area in which they function (takes quite awhile). However, when this takes place, the stator may very well, when cool, function like new... but as it heats up, (and too hot to touch is normal), the AC voltage it delivers to the powerpack capacitor drops resulting in weak, erratic, and eventually no ignition... until it cools off once more. It will eventually fail altogether if this meltdown scenario exists.
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Also an occasional happening:
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Erratic/intermittent engine shutdowns can be contributed to a slight voltage leakage within the ignition switch that allows DC voltage todroft from the "B" (battery) terminal of the ignition switch to the raised "M" terminal to which the "Black/Yellow" wire (kill wire) is attached that leads to the kill circuit of the powerpack.

To check for this condition:

Remove the black/yellow wire from the ignition switch "M" terminal... Connect a volt meter between that "M terminal and any ground... Have the meter adjusted so that it would read the slightest amount of voltage existing... While viewing the meter, turn the key to the ON position (engine NOT running). If the meter shows a reading of even a micro-volt, replace the ignition switch.

This problem is few and far between BUT it does still happen. It will cause repeated shutdowns of the engine and eventually result in the destruction of the powerpack.
 
Keep it simple.......when it shuts down is the perfect opportunity to isolate the cause. Check for spark (as suggested above) but also have a squirt can of premixed gas to squirt into the air intake to see if it is a fuel starvation problem. Also check the tell tale for proper water flow (overheating)
 
Million thanks everybody!

Will start with examining and, possibly, changing the stator and report if anything changes.
 
OK, just hijacking my own thread:D. I found the same year and model motor as above for really cheap. Checked it out yesterday and found that, after running for some time on idle, it would shut down. However, if at the first sign of it going to shut down you prime the fuel bulb, it will regain the power and keep running (until another prime is needed). Seems as if there is a problem with the fuel supply. Just would like to confirm that I am correct in my assumption and any suggestions on where to start my investigation.

P.S. The compression is 140+PSI on all 3 cylinders and, otherwise the motor looks and sounds fairly healthy.

Thank you,

Vlad
 
You haven't explained why your own motor will not start until an hour has passed by. Do you mean that when you try to restart it, it takes you 1 hour to decide to pump the primer bulb? This is not your problem then. Gotta be lack of spark, brother!
 
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