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Offline bizler

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Spark plug wire disconnect
« on: August 16, 2018, 11:34:10 AM »
On my trip on the Wilamette River yesterday my engine quit twice. Having had this happen previously, I suspected the problem was with the spark plug wire. After paddling a few hundred yards to shore to a little niche among rocks and concrete, I pulled the engine cover and found that the plug wire connector had come loose from the spark plug.  The cap was still secure on the plug. I plugged it in and was on my way again and resumed my trip down river.

After cruising about a mile or so, the same symptom, popping and sputtering, reappeared. I was fairly close to the shore this time and coasted to a small beach. Same problem.

I had been cruising at 3740 rpm on both occasions. After plugging the wire back in again, I proceeded down river. I reduced the speed to about 3100 and made the 3 miles back to the ramp without incident. I suspect that the vibration frequency at the higher rpm for an extended period of time, plus normal wear and tear on the connector, were the primary cause.

At home, I pulled the engine and inspected the spark plug cap and the wire connector. Both seemed to be normal, although there was a bit of axial play in the connection.

The solution I have employed is the machining of a new cap for the spark plug that has considerably more bearing surface than the original cap.  I am hopeful that this remedy will keep the connector attached. The attached photo shows the difference in the original and new cap.

Bill.  ;)

Offline Painlesstom

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Re: Spark plug wire disconnect
« Reply #1 on: August 16, 2018, 02:58:29 PM »
Sounds like your plug wire cap is worn out, if your fix doesn't get the job done I would just replace the coil. Only $14 and easy to swap out. https://www.ebay.com/itm/New-Ignition-Coil-For-Robin-EX13-EX17-EX21-Rep-277-79431-11-Engine/302846489294?hash=item46830eb2ce:g:JwkAAOSwk1NbZTVR
Tom

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Offline bizler

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Re: Spark plug wire disconnect
« Reply #2 on: August 16, 2018, 03:05:03 PM »
Good advice. If my fix doesnít work, I will do just that.   \./8

Offline Hillbilly

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Re: Spark plug wire disconnect
« Reply #3 on: August 17, 2018, 07:32:38 AM »
Don't forget that the cap screws into the wire.  You can replace just the cap.  I carry a spare

Offline happul3

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Re: Spark plug wire disconnect
« Reply #4 on: August 17, 2018, 08:39:54 AM »
Don't forget that the cap screws into the wire.  You can replace just the cap.  I carry a spare

Does it mean that one can buy the part Tom mentioned ($13.99 coil) and uncrew the the cap from it for future emergency replacement in the field?   

Offline Painlesstom

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Re: Spark plug wire disconnect
« Reply #5 on: August 17, 2018, 08:56:32 AM »
Yes, I forgot all about that. Thanks for the reminder, George. The caps unscrew simple as pie. I've got an extra you can have, let me know and I'll send it your way.  \./8
Tom

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Offline CC-Coder

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Re: Spark plug wire disconnect
« Reply #6 on: August 17, 2018, 10:29:14 AM »
Yes, I forgot all about that. Thanks for the reminder, George. The caps unscrew simple as pie. I've got an extra you can have, let me know and I'll send it your way.  \./8

Iíll take an extra one or two if you have anymore. Iíll be ordering the coil assembly for a winter project since my plastic plug cap got cracked during shipping of the intercooler.
🤦🏼‍♂️ Chuck 🤷🏻‍♂️

Offline Painlesstom

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Re: Spark plug wire disconnect
« Reply #7 on: August 17, 2018, 11:40:34 AM »
I just have that one. You need the wire and cap, so whole new coil would be what you need.
Tom

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Offline bizler

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Re: Spark plug wire disconnect
« Reply #8 on: August 17, 2018, 11:58:50 AM »
Don't forget that the cap screws into the wire.  You can replace just the cap.  I carry a spare

Thanks, hillbilly, for the clue. I think I may have an extra cap from the EX17 head donor engine in case I need it. :)