Johnson CD-13 trouble shooting.

[joshadurham]

I remembered something that was happening the day my cd-13 started running bad. While running at WOT for long stretches, it wouldn’t immediately die when the throttle was turned to stop. It would kind of lope along for a few seconds then quit. What causes that? Too lean a mixture?

[frankr]

Just hard to kill a Johnson. Seriously, you probably have guessed right. After running at WOT, the crankcase is pretty well purged of puddled gas. I don’t think the term "too lean" applies though. You should adjust it for best sustained idle.

[legendre]

quote joshadurham:

What causes that? Too lean a mixture?

Ask yourself this – why is it that the motor should die when the lever is moved to the ‘Stop’ position? Sure, the carburetor is completely shut down and the timing is fully retarded – but the ultimate reason is that the kill switch is engaged in that position. The kill switch shuts off the spark to as you push it toward ‘Stop’. ETA: No it doesn’t – see Mumbles’ comments, below.

So if it continues to run, there are a couple of possibilities. Either the kill switch is defective – not killing the spark, or there are hot spots in the combustion chamber(s) (carbon, hot plug tip, etc.) that continue to ignite mixture in the absence of spark, causing what’s known as run-on.

Hook up a timing light or other spark tester, and see if the spark goes away when you try to stop the engine. If it doesn’t, the kill switch is bad – if it does kill spark, and it still runs-on, I’d decarbonize the motor.

[Mumbles]

Sorry, but no kill switch on a CD 13. Study a diagram.

These motors are designed to shut down when the grip is fully turned to the stop position which retards the spark so far it can’t possibly run. Maybe that’s what you are doing Josh, turning the grip too far.

[legendre]

quote Mumbles:

Sorry, but no kill switch on a CD 13. Study a diagram.

Thanks for catching that, Mumbles.. I had no idea these motors lacked a positive kill switch.

(Now why would that be? Hmmph..)

[joshadurham]

Thanks. Yea I dont know, it worked flawlessly until later in the day after a long day of running the paddle trails at caddo lake TX. After long runs with it wide open, when turned to stop, it would putt putt for several seconds, then finally die. weird.

[pappy]

….if you are not absolutely sure you are writing fact…….why potentially mislead and write it as fact?

[fleetwin]

Well, I for one, kinda think it is a good sign that the engine doesn’t want to die out to quickly when the throttle is completely retarded to the stop position. This engine must idle very well at low throttle settings, or else it would die out easily with the timing retarded. I suppose the throttle linkage might be messed up/stiff, causing it not to retard the timing enough to shut the engine off.
In any event, I don’t think the two "symptoms" are related.

[kevinrude]

quote fleetwin:

Well, I for one, kinda think it is a good sign that the engine doesn’t want to die out to quickly when the throttle is completely retarded to the stop position. This engine must idle very well at low throttle settings, or else it would die out easily with the timing retarded. I suppose the throttle linkage might be messed up/stiff, causing it not to retard the timing enough to shut the engine off.
In any event, I don’t think the two “symptoms” are related.

Interesting point. My CD-13 cam follower used to get stuck in the open position. When I throttled down, the motor would sputter, lurch and then quit because the timing was off. A liberal amount of grease and a good spring on the lever took care of the problem.

[joshadurham]

Quick question… How or can you clean the metal fuel filter element?

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