excessive voltage?

[bfi]

1976 70 hp Johnson. I'm not too sure how to accurately describe the problem but it appears to be excessive voltage at the spark plugs. The spark will jump thru the boots intermitently. The coils and plug wires are new. This has occurred on 3 sets of new plugs . Tried 3 sets of plugs from 3 sources thinking it might have been a bad batch of plugs. Tried using them straight out of the box at 0030 thinking the plugs might have been damaged in gapping all with the same result--change plugs run a while starts idling funny . Looking at the porcelyn on the plugs it has a black hue to it. Looking back thru old threads makes me think power-pack. This being a somewhat expensive component I would like to know if I'm leaning in the direction before making the purchase.

Thanks in advance, John D.

 

[ezeke]

Re: excessive voltage?

More likely that someone is trying to put automotive spark plug wires on the engine, which won't work. You need solid core.

 

[F_R]

Re: excessive voltage?

It is NOT excessive voltage, nor a bad power pack. What it is is poor spark plug boots. Get some good quality boots from a dealer. A dab of grease in the boots will help prevent arc-over.

 

[bfi]

Re: excessive voltage?

Thanks for the replies. The coils, wires, and boots are all new and were purchased from a local evinrude dealer. I'll try the greese thing and see what happens.

Thanks John D.

 

[Solittle]

Re: excessive voltage?

Careful - some brp/omc/evinrude dealers sell after market parts as well as factory.

 

[bfi]

Re: excessive voltage?

I here what your saying about aftermarket stuff but in this case the new coils etc are oem. . I'm not much on aftermarket unless it's my last resort.

Am I incorrect to assume that the power-pack could potentially be the cause of excessive voltage?

Once again I appreciate the advice/replies, John D.

 

[wilde1j]

Re: excessive voltage?

The PP does not generate high voltage, the coils do. The PP provides the correct timing of the spark for each cylinder.

Don't just use any grease on the boot, use non conductive dielectric grease. You shouldn't be getting black marks on the plug porcelain. That indicates arcing from the top of the plug to the lower grounded section and indicates something is providing a conductive path inside the boots.

 

[Molaker]

Re: excessive voltage?

Angleton, TX, eh? Get's pretty humid there doesn't it? Under those conditions, it's not too difficult to picture an arc over on occasion. And, once it arcs it leaves a carbon trail that makes it even easier to arc again. Clean the porcelain or replace the plugs (again), clean the inside of the boots with alcohol and then apply grease like FR said. But, use the right kind of grease like wilde1j said. The grease will seal the space between the plug and the boot as well as make it easier to fully seat the boot on the plug.

As for "excessive voltage" - never a problem in the high tension part of the ignition. If it is high, it's because the gap it must jump is too wide. "The gap" includes any bad connections along the way from the coil to the sparkplug such as where the boot seats on the plug or the wire connects to the terminal. The voltage will only build to the point where something gives. If everything is right, that will be the sparkplug gap.

 

[F_R]

Re: excessive voltage?

As just said, the voltage rises until the energy is able to go someplace, the intention being across the spark plug gap. Once it sparks, the energy is discharged and it is all over till next time. There is no such thing as excessive voltage on a spark plug wire, assuming good plugs.

There is an important law of electricity that states that it will follow the path of least resistance. If the resistance is less across the boot than across the spark plug gap, that is where it will go. That is where it is going in your case. And the reason for the grease, to increse the resistance. Many factory service manuals say to use OMC Anti-Corrosion Lube grease. But dielectric grease is even better. If your boots are good, not carboned from arcing, and fit the plugs' porcelin tightly, and nothing conductive inside them, and insulated with dielectric grease, you should be able to dump water on them without arcing out.

 

[Silvertip]

Re: excessive voltage?

Are you sure you don't have a cooling system leak that is "misting" water on the plugs which creates an easy path for arcing? Also make sure the plug wires are "snapping" onto the tip of the plug. It is very easy on OMC wires for the ring type connector in the boot to miss the tip of the plug. I hate those terminals and replace them with NGK motorcycle style phenolic plug boots that have brass components and a nice seal. You cannot use the type with an internal resistor however.

 

[bfi]

Re: excessive voltage?

You know guys one of these days someone needs to write an outboard repair for dummies. About the time I think I know something something weired like this comes along. There is a lot to be learned manuals are one thing and real world hands on experience is another. I appreciate y'all sharing your knowledge with me on this issue. From here I will clean inside of boots, apply dielectric grease, and install fresh plugs . We'll drag it down to the bayou and see what happens. I'll report back and let ya'll know how it all works out.

Thanks, John D.