coils light up in the dark

[tal]

1989 pro50lf, still chasing what sounds like an intermittent electrical snap during operation. Runs fine at WOT and on plane but idle is poor and hesitant while throttling up. I just soaked the carbs for 3 days in dip, making sure the jets are clean and everything in place. I'm sure this isn't a fuel issue. There is no backfire through the exhaust or lean sneezing, just a snap and rpms drop down, sometimes killing the engine. The snap only occurs at idle.

I noticed when I pull #1 the engine idles without the snapping. I attempted to pull #2 & #3 with my rubber insulated channel locks and got a snap through my hands. It appears the rubber is letting spark leak out quite easily so I started it up and watched in the dark. I could not see any arcing at night so I pulled the top plug as I did earlier. What I did see was pinkish blue fire wrapping around the coil. All of the coils did this as I unplugged them one at a time and observed in the dark. Once I got to #3, the plug cap would arc out on the metal around it no matter how I curled it around to prevent it.

My question is, the spark leaking out of the coil normal when the plug wire is unplugged from the spark plug? I'm the spark has to go somewhere and all the coils do it, but the leakage seems abnormal. I can't replace just he wires on this thing. I wouldn't think they should shock me through insulated pliers. Any ideas?

 

[Mas]

Re: coils light up in the dark

The coils are getting energized while running and must go somewhere. Sounds like its grounding to the block. I've never seen a coil do that (pinkish glow around the coil)...makes me want to go try it.

When voltage is high enough, as a coil will generate, it can go through insulated material. Try standing on some dry wood boards and see if you again shock yourself. You're obviously a conductor and a pathway to "earth."

My suggestion is to get an adjustable spark gap tester to test how far the spark will jump to test your coils. These testers safely ground the spark with less concern of vapor ignition..as well as potential electrical system damage.

Mas

 

[JustJason]

Re: coils light up in the dark

Your coils are bad and need replacing. When you disconnect them from the plugs when the engine is running you essentially have infinate resistance to ground. If you have no path to ground (via the spark plug) then you do not have an electrical circuit. The coil is making its own circuit by leaking through the plastic, which it should not be doing.

An easy test for coils and plug wires is to get a cheapie test light. Ground the lead for the light and with the probe end, run it up and down the wires, run it around the coil housing. If spark jumps to your test light instead of staying where it should then the parts are defective. (no you won't get zapped by doing this)

 

[stylesabu]

Re: coils light up in the dark

A jumper wire attached to an insulated screw driver will do the same thing. also a light mist on wires and coils will also help pin point a spark leak.

 

[tal]

Re: coils light up in the dark

It looks just like one of those clear glass ball things that came out in the 90s and were popular for a while. The thing you could put your hand on and it follows your touch around with a pink/blue light inside the glass. Except I'm thinking this stuff wouldn't be as friendly if I were to touch it. I'll do a bit more research before I replace these puppies..they're $75 a piece, ouch..