Please Help!!! Spark Plug Arching

[csturgeon80]

Hey guys... gotta problem that's kinda stumpin me... First off the boats a Tarpon 15 foot center console I bought a few weeks ago for a grand.... the motor is a 97 70 Horse Evinrude 3 cyl 2 stroke...
Spark plug is arching on the bottom cylinder causing obviously the motor to miss.... already changed the plugs... made up new plug wires for it.... and even swapped the top cylinder coil with the bottom one...(still arching on the bottom_... when I say arching...at night in the water a blue spark covers all the visible white of the spark plug from the boot to the block... (I even changed the water hose that runs in the general viscinity thinking it coulda had a minute' leak that may be leaking on the plug).... and finally I checked the ground to the powerpack and it is good.... I'm about outta ideas... I don't know boat motors real well... but I do low voltage electronics for a living...so one would assume I'd be able to figure out an electrical problem..lol....
Finally compression test averaged about 135 lbs per cylinder....it was like 138...134....135.... so not to bad.... any help would be so greatly appreciated...(my first boat...dieing to take it out without stress for the first time)...lol

 

[freddyray21]

Re: Please Help!!! Spark Plug Arching

If it is arcing then there is a break in the insulation at the boot most likely. Did you change the boot?

 

[Joe Reeves]

Re: Please Help!!! Spark Plug Arching

As Freddy indicates above, installl a new boot and spring terminal as follows..... then coat the porcelain portion of the spark plug(s) with an anti corrosive grease.

The rubber boot, spark plug end.... With the wire cut to the length required, trim back 1/4" insulation again but do not solder tint the wires. Simply fan out the wires and fold them back against the insulation, cutting the excess off as explained above. Holding the spring wire terminal, estimate where the prong should be inserted so that the spring will be flush against the exposed wire. Hold the spring terminal away from the wires end (sideways) and insert the prong into the insulation and into the center wire, then swing the spring terminal in front of the exposed wire portion (makes a tight fit for continuity purposes).

Spraying the inner portion of the boot where the wire will insert with a small amount of WD40 makes the installation of the wire a easy project. That's it.... you're done.

 

[csturgeon80]

Re: Please Help!!! Spark Plug Arching

Yes... I replaced the boot and did everything as described... also tried 3 more sets of plug wires that I had a mechanic friend of mine make up, thinking maybe somehow I screwed it up......still no luck, it's almost as if the spark is trying to find a ground... somebody stated that it could be a bad powerpack...

 

[Mn Warrior]

Re: Please Help!!! Spark Plug Arching

How does the engine run, just a misfire or not running well at all? Was the problem there when you first got the motor or did it happen after doing tune-up? You replaced the plugs and wires, are the threads clean(no paint) and plug gap is correct?

 

[csturgeon80]

Re: Please Help!!! Spark Plug Arching

The plugs are clean...no paint... running 50 to 1 mixture... it's been doing it since I got the motor.....gap is at .030 .... and I tried swapping the plug wires from the non arching top cylinder to the bottom... and it still arches on the bottom cylinder...so I know it's not the plug wire...(not the coil as I've stated in the starting thread)....motor idles pretty good...every once in a while you here it stutter.... when I got the boat...I heard the motor idle...and thought it'd be good...but the first time I put it in the water...as soon as I'd put it in gear..it'd die (back pressure on exhaust etc)... so I had a friend look at it when we went night fishing...and he asked me to see if I could see it arching...and it was.... idle is decent...motor doesn't die... put it in gear..and it tries to die..sputters and every once in a while you can get forward momentum...then...all of a sudden it'll get a burst of speed and get up to an average of 30, (but it's got alot more potential)...you'll get surges where it's bouncing off 50 mph....so WOT is kinda awkward...I've noticed if I advance the valve on the electric fuel primer solenoid... it also tends to arch more at higher RPM....
I hope I gave ya'll enough info...it really is quite confusing....

 

[csturgeon80]

Re: Please Help!!! Spark Plug Arching

sorry...brain fart...advancing to half way on the fuel primer valve it'll get the temporary surges where I'm hitting 50 MPH... (don't believe the issue is with the primer valve...cause it chokes the motor as advertised... think it's just flooding the carb with a sufficient amount of fuel to kinda benefit the erratic spark from the arching plug

 

[Mn Warrior]

Re: Please Help!!! Spark Plug Arching

Getting too much raw fuel in that cylinder for the plug to fire? Have you tried to restrict the fuel flow to see if the arcing stops?

 

[csturgeon80]

Re: Please Help!!! Spark Plug Arching

I've leaned out the carbs to restrict the flow...but still get the arch.... seriously confusing the heck outta me...

 

[R.Johnson]

Re: Please Help!!! Spark Plug Arching

What wire did your friend use? Not carbon core by chance?

 

[csturgeon80]

Re: Please Help!!! Spark Plug Arching

I honestly couldn't tell you... I went to Auer Marine and purchased Evenrude Plug wires and boots...(non-resisted)...the plug wires are black...no off color....gave them the year model and all of the motor..it's kinda like co-ax... RG-59....or close to it..but the center core is stranded..and the rubbers hella softer...kinda like you'd find in an electric guitar amp wire...I've even alternated to the wires that were on the motor when I bought it...(non arching top and middle cylinder wires..)...all I can figure...is the guy who sold me the boat saw me coming..lol..being a newbie and all..but I intend to be smarter than him and fix it.... when it opens up...it runs like a scalded dog...quite proud of the boat..and for a thousand dollars...I expected a challenge...so I'm not like pissed or anything...kinda figured I'd be washing alotta use...winters coming fast...plan on seacasting the transom and redoing the floors and stringers....(kinda a winter project)..and have a very nice boat before next spring...but my twins coming in town next weekend...and I promised I'd take him out...so I'm busting butt to at least make it reliable by the time he gets down..lol

 

[R.Johnson]

Re: Please Help!!! Spark Plug Arching

Stranded wire is the correct wire. I once used a Sierra boot on a plug wire, I could ground out the plug right through the boot.

 

[roscozen]

Re: Please Help!!! Spark Plug Arching

i had exactly the same prob w/my 35 johnson and went nuts like you are. coated everything in the area w/liquid electrical tape to stop it.
that winter i opened the wire bundle that runs across the top of the head over the powerpack and coils and found the problem was fried, open wires .after replacing these (one by one) the problem never returned.good luck.

 

[Willyclay]

Re: Please Help!!! Spark Plug Arching

I've seen some posts here where people say they used NGK motorcycle boots to stop an arching problem. Good luck!

 

[csturgeon80]

Re: Please Help!!! Spark Plug Arching

Bout to catch that tropical storm...and I'm in a flood zone...so I'm picking up electronics...but as soon as the rain stops...I inspect the heck outta that wire bundle and see if I see any bad wires.... I'll let ya know... thanks a bunch for the suggestion

 

[Sea18Horse]

Re: Please Help!!! Spark Plug Arching

Hmmm, weird! So did you replace the plugs? Or at least try swapping plugs between cylinders? In automotive you often get carbon tracking in spark plug boots. You must replace both the wires (boots) and the plugs at the same time. It does no good to replace just one or the other. They'll just re-carbon track again.

Cheers.............Todd

 

[CATransplant]

Re: Please Help!!! Spark Plug Arching

Bingo! If you did not put new plugs in there, try that. You didn't say anything about replacing them. A virtually invisible crack in the porcelain of the plug can cause arcing.

What do plugs cost? The first step when you're having problems like yours should be a set of new spark plugs.

If you didn't do that, do it. I'm betting your problem will be solved.

 

[freddyray21]

Re: Please Help!!! Spark Plug Arching

read first post he changed the plugs. If it continues to do it after changing the wires it is not the wire. What other wires are in that area as that is your problem.

 

[Sea18Horse]

Re: Please Help!!! Spark Plug Arching

Freddyray21 wrote;

"Read first post he changed the plugs."

But it's not clear whether he changed the plugs before the problem cropped up or after. And it's not clear whether he changed the plugs and wires at the same time. That's key.

"If it continues to do it after changing the wires it is not the wire. What other wires are in that area as that is your problem."

I respectfully disagree. We're making this too complicated. No other electrical problem in the whole rest of the vehicle is capable of causing this problem. It doesn't matter if it's on an outboard, a car, a tractor or what. Electricity always follows the path of least resistance. In this case it's easier to leak along the porcelain than it is to jump the gap.

Now are we sure that the cylinder in question is dead when the arc is happening? When a plug and wire carbon tracks or leaks it's always a lightning bolt like arc. It's not like a halo or an aura like you'd see inside a vacuum tube. (for those of us who remember what vacuum tubes look like !) If the cylinder is not dead when this is occurring and it's not a lightning bolt like arc then we'd better contact Scully and Mulder 'cause that's not possible.

The truth is out there!

Cheers................Todd

 

[Okee Jimmy]

Re: Please Help!!! Spark Plug Arching

Just a thought, but you mentioned that manually opening the enrichener valve made the motor perform better at high rpm's. Maybe the bottom carburetor is partially restricted. A lean mixture is fairly hard to ignite, this will drive the voltage potential way up and as mentioned above the spark will follow the path of least resistance. Also, after spark has leaked past the boot, it will create carbon track, and the new boot on that bottom cylinder may already be ruined.