intermittant cylinder on 65hp

[brownboat]

First time poster. Great site!

I have an old evinrude that developed a problem.
1973 evinrude 65 hp (model 65373) with very low hours that only runs on two cylinders until it warms up. This just started happening the end of last season. When I first start it up I putz around at 1500 rpm for about 10 minutes because I can't get on plane. Then all of a sudden it’s running fine and stays that way for the rest of the day (unless it’s off for more than an hour). Idles great, no hesitation, rpm at WOT is 5200.

On some days when it’s real hot outside and the boat is in the sun, it starts and runs fine right away, then after about 2 minutes a cylinder will drop and I have to wait for the thing to warm up. It’s as if the cooling water cools something off and I have to wait for the engine to warm up. Squeezing the fuel line bulb doesn’t make a difference. If I hit the choke the engine bogs down.

I removed one spark plug wire at time and ran it to a spare plug grounded to the block.
It looks like the #2 cylinder is the one that doesn’t work when the engine is cold. With everything wired normally, I squirt some fuel into the #2 carb and it makes no difference.

I noticed a crack in the casing of the coil for #2 and replaced it with a new coil, but it didn’t make any difference. The resistance of the coils (trigger?) under the flywheel all look exactly the same. I have not done a compression test. I bought some sea foam to decarb, but haven’t run it through the motor yet.

Has anyone seen this type of behavior? It sure seems electrical. I’m thinking of replacing the power pack.
Sorry for the rambling. Thanks for any help

 

[imported_lorin]

Re: intermittant cylinder on 65hp

One quick check you can do is move the coils around and see if the problem follows one of the coils. An easy way to check for spark on each cylinder with the motor running is put a timing light on each cylinder one at a time, pull the trigger, and just watch the light to see if it stays on steady or dies out.

 

[KYHunter2]

Re: intermittant cylinder on 65hp

I wouldn't start, replacing ignition components.

Until you trouble shoot your problems .

You can fry new parts , if you dont first , find the problem.

If it were me, I'd check , the whole elect. / ignition system .

From top to bottom, ie: grounds, ign. switch , wiring , plugs , etc. etc. etc.

The pins , on the amphenol plugs, often get corroded over time.

It doesn't take much to cause, all kinds of problems, bad grounds , also.

KYhunter

 

[tashasdaddy]

Re: intermittant cylinder on 65hp

since the engine faq is down, go to boatpartstore.com click outboard trouble shooting, under johnson , you will find the test and instructions for the elect system.

 

[brownboat]

Re: intermittant cylinder on 65hp

Thanks for the advice. I'll try the test procedure from boatpartstore.com this weekend. I have access to a scope so I might also try to look at pulses on the powerpack.

 

[brownboat]

Re: intermittant cylinder on 65hp

In the test procedures from boatpartstore.com it talkes about testing the coils/powerpack and using a load resistor in place of the coil. Does anybody know what resistor value or wattage the resistor is?

 

[KYHunter2]

Re: intermittant cylinder on 65hp

I believe i-boats sells a load resistor/ tester .

Just for this purpose. Check under testers / meters, along those lines.

Just for future reference, the value of a resistor, is measured in ohm's, not watts.

Watts are a measure of power, typically
amps X volts = Watts.

In a solid state resistor , the colored stripes are how you get the value.

There are values for the different colors, a multiplier , and if applicable a tolerance band.

Really not something you need to know , just rambling. LOL.

KYhunter

KYHunter

 

[brownboat]

Re: intermittant cylinder on 65hp

Thanks for the response kyhunter2. I guess what I was trying to ask was the ohms and watts of the resistor. I didn't want to grab a 1/4 watt and have it burn up on me during the test d
It turns out I don't need it after all. A friend has a portable (battery) oscilloscope and we checked the timing pulses going to the powerpack and the trigger pulses going to the coils. No output to the #2 coil. I swapped coils and the problem stayed with the #2 cylinder. I think I'll be shopping for a powerpack at i-boats.
By the way, as you suggested, I went over the whole electrical system, grounds, connectors, etc.
Thanks again

 

[KYHunter2]

Re: intermittant cylinder on 65hp

Your welcome, and just to clarify.

WATTS has nothing to do with resistance/resistor.

OHM's is what resistance is measured in.

It is the amount of resistance to current flow.

Watts is a measure of power.

KYHunter

 

[brownboat]

Re: intermittant cylinder on 65hp

Installed the new power pack this weekend and that fixed the problem. I also did a sea foam decarb...the motor is running great nowd Thanks to all for the troubleshooting suggestions.