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1982 20 hp Evinrude cutting out one culender

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BCboater

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Hi, I recently bought a 1982 20 hp Evinrude and I cleaned the carb, checked the fuel pump, new spark plugs, coils seem good, new plug wires. It starts after 2-3 pulls cold. When I runit up to speed on my 12 foot aluminum boat, it runs fine for a bit, then seems to cut out on one cyl. It'll cut in momentarily now and then, but goes back to one cylinder. Then it stayed running one 1 cyl all the way back to the dock. Even at idle. Could the ingnition modual be going bad? Wires all look good. I don't really want to cut into the wires to chek for a possible open in one of them, but it may come down to that. Any hints as to where to look? Maybe I missed someting in the carb, but it's strange that it cuts out on one cyl, and keeps running on the other.
 
You can do a spark jump/gap test....take out both plugs and pull it over to determine which cylinder is weak or dead. Should jump a gap of 3/8 to 7/16" with a nice lightning like crackle. I have seen these have internal arcing in one of the final coils causing a problem too....which might not show up in an ohms test. Once the CDI module fails it is oftentimes not intermittent, as your symptoms indicate.
 
Thanks timguy. I'll do some more checking of the spark. I got a new modual, so might as well put it in. Have you had coils break down just some times, but work well other times? I might just put a set of coils on after a test run with the new modual if it doesn't help. I have a good running 9.9. Would the coils be the same? Maybe do a swap.
 
Thanks guys. I've got a pretty busy schedual, but I'll do the modual swap and give it a try. Might even bring the coils off my 9.9 to swap over with me to the lake when I go.
 
Okaaay! That really might not have caused the symptoms that you experienced. But stranger things have happened.
 
Problem was said to be " cutting out on one cylinder " and advice was based on that.------Far different was the actual issue of a lack of fuel.-----Strange.
 
I'm still trying to wrap my head around why one cylinder was cutting out also. One time I idled back to the boat launch about 1/4 mile and it was definatly running on one cyclinder because I pulled the plugs and the top one was soaking wet while the bottom one was dry and normal. ??????

When I pumped the heck out of the primer bulb, it ran great, jumped up on plane with 2 people in it, and ran up to 40 kph. Stop pumping and it dropped off right away. It's raining today, so I'll give it a go in a day or 2.

BTW my boat (12 foot Edson) and motor is 360 pounds, plus me and a buddy add anothe 400 pounds. We got to 40 on the GPS.
 
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I've been playing with 2 stroke motors since I was a kid. Bikes, chainsaws, outboards, etc, but never ran across a symptom like this before where it runs on one cylinder and not both when it leans out. Is there a strange air/fuel flow design or what else would cause this? The reeds look good, no obvious crank seal leaks. Any ideas?

Usually when a 2 stroke is running out of fuel, it picks up a bit and then all cylinders drop off.

I'll find out if it's fixed after a good run soon.
 
Had a phone call from someone in BC yesterday.-----Looking for motor parts.------The man thanked me for my knowledge and having the parts for his old motor.-----I always used too ask folks the ---" what is your motor doing / not doing " ----Then I did the diagnosis.----Folks coming into the dealer 50 years ago were often wrong with their diagnosis.-----Same here on this and other websites.-----Sorry if I sound blunt.
 
Thanks for your input Racerone. From my experiance, your suggestions were completely with my thoughts. I don't mind that I put some new parts into this motor. I'll probably get the money back when I sell it down the road.

The guy I bought it from said it worked fine, so I should have looked at my tank pickup line earlier, but hindsight is just that, hindsight.

Still have to go for a run.
 
Well, I did a test run yesterday and one of the coils I bought from Amazon died! Came home and swapped the old good coil in and it's running good in the test tank.

Went out for another test run this morning and it fired right up, then died! Traced it down to the stop button. Disconnected it and it started. Idled out to the area of the lake where speed isn't restricted to 15 kph and turned it up. Ran up to 41 kph with 2 of us in it, and went the full 5 km and back without a hitch. Finally! I did raise the float level a bit to richen it up some. I'll take a look at the plugs to see if it's rich or lean.

Hopefully it'll get me to the far end of Azure Lake. It's a 50+ km trip up Clearwater Lake, Azure River, and then Azure Lake. No civilization around or cell service, so if it quits up there, it's a looonnng row back to the boat launch.

BTW, the kill button fell apart, so something else to fix now!

Thanks for the pointers and input guys. Happy Fathers Day!
 
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OK, It's running lean it looks like to me. Any idea what size main jet I should go to? It still has the 20 hp carb on it, but I matched the intake manifold (that originaly had only a 3/4 or so diameter hole in it) to the carb size. Is that why it's running lean? I'm running NGK BR6HS plugs.
 
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