Fouled plugs..and why..?

[Eddie O'Dell]

With do respect to our membership, what really is a "fouled spark plug" and why do you think so .........Just curious for our readers, since we have a broad reason to know...?

[JoshV]

To much fuel = Carbon build up

[SMGranny]

No worky no MO

[Eddie O'Dell]

Rather interesting comments thus far. What really is a fouled plug, how does it get there and why..?

[SMGranny]

Old age

[Lynk]

Hehe... ^^^ said by the fouled rider.

[Eddie O'Dell]

To much fuel = Carbon build up

Too much fuel (or carbon build up) equals a good path to ground and thus will not warrant a fouled plug. The shear fact that Carbon exhibits a good ground path for the spark to begin with is justification as to the continuing effects of why people think a plug is fouled. So why and what is really a "fould plug". ?

[Eddie O'Dell]

Anyone , anyone, anyone , where is ferris,..........

[Eddie O'Dell]

UUM how can this be , if a solid state of known carbon or other form of matter on the Table of PERIODIC ELEMENTS, then what is it that this condition MUST be held as a true statement.

[Jive]

Is it that the jetting out or to much oil?

[Eddie O'Dell]

A fould plug is said to be anything or condition that causes the current traveling along the center electrode within the plug,to take a path of lesser resistance to the grounding shell. This usually occurs deep within the plug, or near the area where the porcelain meets the outer metal shell or threaded case of the plug. I once had a parts mgr. throw me a plug from @ 20 ft. away, I dropped it, picked it up and threw this (brand new plug in the box) one in the trash. A heated argument ensued, I was able to convince him of why I tossed it. I see people handling plugs roughly, throwing them in tool boxes, etc. If you've ever wondered why an engine's ignition system is failing and you know you just replaced the plug hours ago, replace it again. You never know how it was handled. This is just one more reason why all testing should be done with a new plug, even if its not the correct plug for the application. Most ignition systems are considered to be good only if the system is capable of jumping a 5-7mm gap for a specific period of time, as on my Suzuki electro tester machine............

[PBMW]

Werd
A plugs being black does most assuredly NOT mean it is jetted incorrectly. It means that incomplete combustion is occuring. It's cause may be any number of thing including jetting, ring seal and end gap, valve seal condition. Many things....
Or as Eddie has pointed out, an iggy issue

[Hakujin01]

A plug rarely actually stops working without hope of fixing it, if you sand the plug it will likely work again, unless something is wrong with the internals of it.

[Eddie O'Dell]

A plug rarely actually stops working without hope of fixing it, if you sand the plug it will likely work again, unless something is wrong with the internals of it.

Sanding or sand blasting a plugs is only recommended as a temporary or trail type fix as doing so technically ruins the plug with regards to the ability of the plug to keep itself clean, when a plug can no longer keep itself clean, its forced to operate outside of its designed heat range and thus as it continues to run at cooler temps, compounding the original issue. Blasting plugs will cause pitting of all the parts and will quickly cause the plug to get even dirtier than before. It will also lodge silica or other abrasive media deep within the plug. Then its propensity to fail is increased.

[C~Style]

so a fouled plug has nothing to do with the plug being saturated with oil/gas or black stuff (that's a technical term)?

[Eddie O'Dell]

so a fouled plug has nothing to do with the plug being saturated with oil/gas or black stuff (that's a technical term)?

Although gas, oil, and carbon are all electronically conductive, they are usually or merely the instruments that may have lead to the no spark condition. When the no spark event has occurred, we are now dealing with a plug that has an "open" circuit or a direct short to ground. Once the soot is removed and a path to ground is restored and there is still no spark, the plug is considered fouled or internally open or shorted to ground. Remember there are only 4 ways an electrical circuit or component part can fail whether its space shuttle parts or Z parts.

1. Direct short to ground.
2. Improper resistance.
3. Short circuit.
4. Open circuit.
Also remember it takes at least 10,000 D.C. volts for a spark to jump across a .030" air gap. If the plug can find a path to ground (the metal threaded case) via a smaller gap or lesser restrictive path to ground deep within the plug it will do so, and sometimes will keep doing so even after the plug has been so called cleaned.

[Hakujin01]

I didnt mean blasting a plug, I mean using fine grade sandpaper on the electrode. Does that actually screw plugs up?

[Eddie O'Dell]

I didnt mean blasting a plug, I mean using fine grade sandpaper on the electrode. Does that actually screw plugs up?

As said earlier sir, sanding a plug is merely a quick check to me. If doing so restores spark for the stricken plug, then that's cool. With success, it only confirms other more predominate issues are present and the plug will soon fail again. By sanding a plug, your actually changing the "arc gap radii" while restoring a relative clean or lessor resistive path to the intended ground strap. What ever the root cause of the initial failure will invariably result in a soon to be plug that has been forced to fail deep within itself, and thus be fouled. Also, sanding a plug also changes or alters the surface finish of all the parts contacted by the sand paper or file, and so not only does it change the surface texture, it also effects the rest of the otherwise possible conductive path's to never be permitted to spark again. And so in due time or quickly, if not immediately, all other options to ground are eliminated, and thus the plug can only keep itself clean in that one place where the arc continues to occur. Generally speaking, a good performing ignition system/plug, if all is perfect, will only spark from the same 2 points from the center electrode to ground once every @ 10,000 sparks. By sanding the plug, your forcing it to go between just 2 points for the rest of its life, hence only being able to sustain enough heat to keep but just one place hot enough to stay clean. Once this in in effect, and if the plug continues to function long enough, errosion begins to occur between the 2 points and gaps are continuing to get ever larger until finally the plug will find an alternate path to ground or NO path to ground at all...........That is fouled. Remember what you can easily see on the end of a plug is not the real story as to its history. This is why we use special viewing scopes to peer deep into the plug, kinda like a doctor uses to look into your ears.

[Hakujin01]

Interesting. I just learned a bunch of things =D The only time I have ever sanded plugs was on snowmobiles, in which case that plug is your ass, you can't just walk home in powder, and thinking back, they did foul like the next day. Lol.

[Eddie O'Dell]

Interesting. I just learned a bunch of things =D The only time I have ever sanded plugs was on snowmobiles, in which case that plug is your ass, you can't just walk home in powder, and thinking back, they did foul like the next day. Lol.

Yes sir, 2 smoker plugs are the most commonly sanded. And your right again, sleds and jet skiis are a bitch to get back home or to shore. So yea, I would sand them too in order to try and get them back, knowing that if and when I did a new plug is quickly in order. This is why these machines have special places on board for spare "new plugs"...............