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blowing coils out

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redsnapper386

Regular Contributor
guys what would cause a thunderbolt-4 unit to blow out coils .is there a certain area for me to test and how.i posted a few days ago about a voltage drop.that issue is solved which was a short in tack gaude.i tried to restart boat today and i heard a pop.no start.i did a spark test right away on coil and no spark.all wires are clean and tight.new battery switch,new ign switch new gauges,all new solinoids,new battery,new dist,coil as part of kit.i put a spare coil on and same results. new alt also.thanks in advance for replys.
 
You think that the rewire you did is shorting out the dist. ??

Maybe leave the tach wire off for now nd install another coil.

Say with the tach wire off and another coil goes then i would think its the Ignition Amplifier Box.

Say it is the IA then i would not spend the money on it.

I would go with a new system altogether. Hei unit all in one unit coil and dist in one unit one wire in one wire out and one wire to the tach bypasses all the bull chit t-bolt sysytem.

Advange is a new dist, will last forever needs no adjusting after setup.
 
I believe that M/C recommends that the OEM TB IV ignition coil only be used.
See your OEM manual and trouble shooting section to varify this.

I would tend to agree with Chief, and would replace that M/C propriatory system, with something that is more reliable, and affordable when it comes to replacement parts.

I don't necessarily think that HEI is required...... but you could certainly do so.
Adjust spark plug gap accordingly if you do.

.
 
guys after more tests i do not have constant 12 v to the coil.can i run a seperate purple wire from ign switch at dash back to and splice into purple wire at the coil or could i do the same thing from my house battery.i have a battery switch.if so this would save some time going through all the wiring.just a thought.thanks again.
 
just run a jumper from the batt to the plus on coil also take off tack wire the gray one if ok mabe you have to run a new purple wire good luck
 
"i have a battery switch.if "
The worst possable way to shut off a motor, find out where your losing the 12V. bad ign switch, engine harness plug.
or a break in the main harness (unlikely)
 
you could at the helm install a on off switch,mark it ign. and then run a wire from the pos, side of the starter. So when you want juice to the coil you flip the switch and use the key switch for the starter.

When you want to shut off the motor you turn the key switch but the motor will stay running you flip the switch the motor shuts down.

It's the way my boat is wired.

You don't want to come off the pos side of the battery, then you will have a big mess.
 
bt doctur thanks for reply i mentioned the battery switch as part of troubleshooting.i replaced ign switch and bat switch.engine harness is clean and not to tight.no fuses blown and all plug ins are good.i feel like there is a short or broken wire somewhere in that ball of wireing.at this point i want to bypass this mess.can i safely run seperate wires to the coil from the dash.purple wire strait to + of coil from the ign switch,and run a gray wire from the tach back to the dist. is this a solve problem approach. all of my other systems work at this point.i have a spare coil,and i do not want to loose that one.thanks for all your help.
 
Have you unplugged the main engine harness plug and looked at it ? Somtimes if the clamp is loose or missing ,corrosion can build up on the connectors. It does NEED the clamp on it
 
you want to hook back up the tach before resolving the coil problem ?

You just don't know how lucky you are that BT choose to reply to this thread.

He is a personal friend of mine and lives nearby me.

If he makes a suggestion i would again look to what he suggests.

My opinion leave the tach wire off. It is a known problem a bad tach can and will destroy coils.

You checked the keyswitch? You could for checking use a momentary switch in place of the keyswitch." A door bell switch just for testing ".

Remember ED the talk we had about the door bell switch for the tilt problem we talked about. Same deal. And your suggestion !
 
Redsnapper,

There is no reason to rewire your ignition curcut!!

You need to do more troubleshooting.

Start at the ignition switch, with the KEY ON do you have 12 volts on the purple wire?
If yes then you should also have it at the choke + and the coil+.
If no at the key switch then find out why?

Also what is your exact problem now??? is it the motor wont start when cranking it over?

If this is the case then you must start at the key swicth again. Disconnect the the small yellow with red stripe wire at the slave solenoid, go back to the key switch, put your meter or test light on the purple wire and turn your key switch to the crank position. Do you have 12 volts there? If not then you have the wrong key switch.

There are two methods of suppling 12 volts to the coil when crainking, one is thru the I terminal on the starter solenoid and the other is thru the contacts inside the key switch. The method using the I terminal on the solenoid was used with point ignitions mostly, with the thunderbolt ignitions they commonly used the ignition switch to transfer the 12 volts to the coil when crainking


Also if you have no 12 volts to the coil you must look at the shift interuptor switch, this switch shorts the ignition to ground when shifting OUT of gear BUT if it is shorted or wired wrong it will defeat the ignition curcit!!


There should be NO need to add new wires. If this is the case BUY A NEW WIRE HARNESS COMPLETE!!!
 
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Hmmmm. Is the coil rated for straight 12 VDC or should it be used with a ballast resistor / resistance wire? Some coils have internal ballast resistors and some other's need external ones OR use a resistance wire. Need to look at service manual and see what the coil actually is rated for / needs. Was any re-wiring done that could have eliminated a resistance wire or ballast resistor? In resistor installed systems, when starting, the resistor is bypassed to allow the full 12 VDC (overcoming battery voltage drop when spinning the starter) for a higher than normal spark, but once starter is dis-engages and engine is running, the bypass is removed, allowing the coil to operate at something less than 12 VDC (I think it's around 7.2 VDC) actually at the primary coil windings. This is what limits the amperage thru the coil. If the coil is designed for a resistor, and it is run on 12 VDC all the time, the coil will overheat in a very short period and give that resounding "pop". If ignition coil should be rated for straight 12VDC and an aftermarket coil designed for a ballast resistor is used, you see exactly the "blown coil" you are seeing as described.
 
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The Thunderbolt V and IV both use the same coil, it is internally ballasted. NO EXTERNAL BALLAST WIRE OR RESISTOR.

Only the earlier point ignitions (GM TYPE) used the resistor wire.......NO external resistor.
With the point ignitions, only during the crainking of the engine the coil received a full 12 volts by way of the starter solenoid terminal I. When the key is released to the run position it then went thru the resistor wire.

My boat the crainking 12 volts is supplied thru the key switch. A couple of years ago my boat would crank but would not start until the key was released to the run position. I removed the key switch and dissassembled it and cleaned all the contacts, ( my ignition switch is servicable) and this solved my problem..........
 
ghost,i will start your tests today and post back,i thank you guys for all input.now to answer questions.ghost,motor will not start.with all of my tests i found a shorted tach,bad key switch.i replaced both new.new parts are idenical.i did a spark test at coil which showed no fire.at this point i will do each test as you instruct and post back. i agree to find the problem.oh,my dist kit is the thudr bolt-4,delco esi-electronic spark ignition which has the built in sensor with the external coil that bolts to the block.the coil is sqare in shape.the purple and gray wires are together in a harness,and plug into distributor,and coil.there are 2 other harness wires that do the same,they are brown and pink,and 1- black ground.i noticed the tach wire has a ground wire tied into it,and goes over,and connects to ground on shift interrupt switch.my manual does not show this system setup.it shows the round coil,and amphlifier type.hope this info will help.thanks.
 
Bt Doctur said:
"i have a battery switch.if "
The worst possable way to shut off a motor, find out where your losing the 12V. bad ign switch, engine harness plug.
or a break in the main harness (unlikely)
Click to expand...

Bt Doctur said:
Have you unplugged the main engine harness plug and looked at it ? Somtimes if the clamp is loose or missing ,corrosion can build up on the connectors. It does NEED the clamp on it
Click to expand...

kghost said:
Redsnapper,
There is no reason to rewire your ignition curcut!!
You need to do more troubleshooting.
There should be NO need to add new wires. If this is the case BUY A NEW WIRE HARNESS COMPLETE!!!
Click to expand...

Amen and No kidding!
All of this so called advice to circuvent a system that needs to work correctly in the first place, is pure sillyness.

Don't take short cuts for your marine related issues.
Find the problem, and make a proper repair. :D

.
 
found my problem guys.i started untapeing the wire bundle at the slave solanoid area,and almost to the alt i found a connection in which both purple,red wire came apart.someone in the past did not do a good job.i like to solder mine .an offshore boat gets alot pounding.i want to thank all for your help.all of the troubleshooting tests will go into my repair notes.thanks.redsnapper 25' sea ray cc.
 
Great!! Someone actually listened and followed advice (over the internet) and found the problem!!!!! Good job!!
 
Ghost,

Good reply. The point I was trying to make is if someone had replaced coil with, say a Chrysler coil (which will fit in the bracket), designed to run on an external resistor or resistor wire, then the problem origionally stated "guys what would cause a thunderbolt-4 unit to blow out coils" could be explained. Just one train of thought, but probably not explained as directly as your explanation.

Pops
 
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