Pulling the plug wires?

[roastinears]

My last motor was a Chrysler 75 hp. When I first got it, it would short back through the distributor always on cylinder #1, sometimes on cylinder #2, but never on cylinder #3. replaced distributor, problem fixed. Now, I get nervous now seeing posts saying to pull the plug wire off while idling and see if it makes a difference. Is this practice always OK, or only once in a while? What happens to the charge when you pull the plug boot on an evinrude? (Path of least resistance). I’m not questioning the advice, just gunshy on the subject.

Thanks

 

[yamamarinetech40]

Re: Pulling the plug wires?

Don't use your fingers, use a tool made to do this, available about anywhere(parts stores). It's made of plastic. You don't say what motor you have....

 

[Silvertip]

Re: Pulling the plug wires?

That's a great way to find a "dead" cylinder. Pulling a plug wire should cause the engine to die or stumble. If you pull a wire and nothing happens, that cylinder is dead because it 1) has no/low compression, 2) no fuel, 3) no/weak spark, or 4) any combination of 1, 2, and 3. If you are shy about doing this in fear of getting shocked, use an insulated pliers when doing this because you will get reminded you are holding onto several thousand volts and you are the path of least resistance. This is a test -- not a prolonged running operation so pull the wire, note the response -- and then get it back on.

 

[roastinears]

Re: Pulling the plug wires?

Thanks for the replies. my "current" motor is an 1983 evinrude 90 hp (E90TLCTE). just picked her up less than a week ago. i'm not worried about getting shocked. more worried about the permanent damage that could be caused by pulling the boot. By the way, this is a GREAT forum. thanks to responders and iboats!

 

[srt4wad]

Re: Pulling the plug wires?

I pulled the boot one at a time on my 85 Johnson 60hp and each time the motor died I am guessing that is what is supposed to happen. If so then that means I don't have a problem with a cylinder?

Thanks
Wade

 

[artherm]

Re: Pulling the plug wires?

I pulled the boot one at a time on my 85 Johnson 60hp and each time the motor died I am guessing that is what is supposed to happen. If so then that means I don't have a problem with a cylinder?

Thanks
Wade

 

[artherm]

Re: Pulling the plug wires?

From personal experience, remember to check the spiral connection wire in the boot when reinstalling. The rubber boot will sometimes spin on the wire, and if you don't check, you might not get a solid re-connection.....

 

[F_R]

Re: Pulling the plug wires?

Pulling a plug wire is a good way to check the cylinder. It is also a good torture test of the ignition system. As you said, electricity goes thru the path of least resistance. If that path is somewhere you don't intend, boodby that component. Of course you can always explain that it was about to go anyway.

I prefer to short out the plug by shoving a skinny screwdriver up in between the plug and boot while grounding the shank to the head till if arcs out through the screwdriver. Besides, I hate getting electrocuted!

 

[imported_MattG]

Re: Pulling the plug wires?

I too hate, getting shocked. The only time I enjoyed it was when I was working on my ol motor all day trying to get spark. When It finally did it gave me a jolt, but it was a jolt of joy.

Ive pulled the cap off of a plug before, you should be fine. Just dont leave it off flapping around sparking on everything.

 

[samo_ott]

Re: Pulling the plug wires?

I just use a good clean rag to pull it off, and as mentioned, keep if off as short as possible and then put it back on.

 

[Silvertip]

Re: Pulling the plug wires?

The process of pulling the plug wire to identify a dead cylinder proves that the "iginition" system is working if there is a noticeable difference in how the engine runs with the wire off vs on. If there is no change, then either the spark is gone, there is no fuel or there is no compression. So the test is not just a spark only test. You may indeed have great spark but if there is no fuel to ignite or compression there can be no explosion.