MrCIG

iTrader: (1)

I have a friend with a Merc Thunder Bolt 4 ignition and he has gone through 3 Ignition coils in his last 3 trips out. What would cause this to happen? Any one have any thoughts?

Thanks
Mark

RedDog382

Any possibility the polarity is reversed?

Dave_N

What replacement coil is he using? Merc, Sierra, something else?

How do the coils that have failed check out (primary and secondary winding resistance)?

How old are the plug wires and plugs?

Dave

rdoactive

Plugs, plug wires, cap, rotor worn and have excess resistance.
Too low voltage to the coil. Did he replace a points system with a TBolt without removing the ballast resistor?
BTW, I've always used $10 automotive (external resistor) coils and never had a failure.
Gary

MrCIG

iTrader: (1)

The boat always had the Thunderbolt ignition. He has put in Accel coils. I don't don't know what the voltage is going to the coil. I will have him check that.

Does the Thunderbolt ignition require the resistor wire. Or is there always 12 volts to the coil?

Thanks
Mark

CcanDo

There may be surge from the alternator.If so, a ballast capacitor is recommended by at least crane and MSD,as a solution for similar problems.But,in twin application the battery switches can also cause feed back surge.Typically,the switches are not to be set on "Both".

rdoactive

TBolt wont have a ballast resistor, full 12V. It's supposed to run a "special" coil.
Tell your friend to buy a cheap external resistor GM coil and try it. If there's excess resistance in the secondary, that can damage the coil too.

Dave_N

What Accel coil is he using? It is hard to beat the performance of the OEM Thunderbolt ignition. Using mismatched parts will usually only reduce performance. Is the coil getting really hot?

rdactive is correct, no ballast reisistor or resistor wire. The tbolt module uses RPM based variable dwell to regulate primary circuit current and coil/module temps.

Dave

Wobble

Coil is mounted in the upright position? Most coils, except severe duty off road type should be mounted vertically.

SB

iTrader: (1)

Does he have something else hooked up to the + on the coil ? I've seen way to many thing hooked up here for some reason - I guess easy place, but severely wrong place, to hook up other powered items ?

Above was just a throw it against the wall and see if it sticks.

Some diagnostics definately need to be done.