Ignition circuit 'burn'!

esray

esray

Member
Dear Forum,

I have electronic ignition which requires a constant 12-volt supply to the coil. To bypass the ballast wire, I have a wire spliced into the thin white wire at the top of fuse 19/20 and led directly to the +ve coil terminal. The thick white wire remains in place. This has worked fine for ages. However, I recently refitted my engine after a rebuild and for some reason, this wire is becoming so hot when the starter motor is turning that it smokes and the insulation melts; this melt continues the live feed from the coil to my dizzy! Fuse 19/20 remains intact. I tried disconnecting (what was left of) this wire and supplying the coil from the 12 volt washer motor supply; again, no start, but this time the fuse (19/20) did blow?

I am lost!

Ray
 
Your coil positive terminal seems to be earthed for some reason.

Once you will find the reason why this happens and rectify the problem, install a new line from the fuse box, but this time include a good in-line fuse just after the fuse box in order to avoid wire melt downs and possible fire in the future.
 
Demetris said:
Your coil positive terminal seems to be earthed for some reason.

Once you will find the reason why this happens and rectify the problem, install a new line from the fuse box, but this time include a good in-line fuse just after the fuse box in order to avoid wire melt downs and possible fire in the future.
Click to expand...

Hello Demetris; thanks for your reply.

I accept what you say, but I do not see how? It is in its holder, with just the +ve and -ve feeds to the dizzy? How do I test my coil to see whether it is earthed? Could it be that the white wire from my ignition switch to the fuse-box became earthed in the meltdown? How do I test, please?

Demetris, which white wire is which, please? Is the thin white from the ignition switch and the fat white to the ballast wire, or vice-versa? Which white should I be taking my live feed for my coil from, please?

Thanks again, Ray
 
Ray, in such cases it is always useful to use a multimeter or at least a test lamp in order to test circuits without suffering meltdowns and blown fuses.

The meltdown happened when you switched on the ignition or when you operated the starter?
If it is the former then probably your coil is causing a short circuit internally somehow, a multimeter will show very little, almost zero resistance between its terminals. Or you could have some problems that are described below.

If it's the latter, then there are many posibilities. Are you sure that you deleted the old feed from the starter solenoid to the coil that was part of the ballasted system? Normally if it is still connected properly it will not make a difference in the operation of your non ballasted system, but if it is not, if it is earthing somewhere, or if the main starter feed does not make good contact, you could possibly suffer the symptoms you describe.

I am not really familiar with the series 2 fuse boxes, but i pressume that the instructions that Dave gave to you regarding the correct point to take the new feed are correct, and in any case this is not the cause of your problem. The only thing that i would like to change is to add an in-line fuse after the splice, in order to prevent meltdowns in the future.

I hope that this helps.
 
Demetris said:
Ray, in such cases it is always useful to use a multimeter or at least a test lamp in order to test circuits without suffering meltdowns and blown fuses.

The meltdown happened when you switched on the ignition or when you operated the starter?

When I operate the starter

If it's the latter, then there are many posibilities. Are you sure that you deleted the old feed from the starter solenoid to the coil that was part of the ballasted system?

The old feed is still there, but it is blanked off - It is not connected to the coil in any way.

Normally if it is still connected properly it will not make a difference in the operation of your non ballasted system, but if it is not, if it is earthing somewhere, or if the main starter feed does not make good contact, you could possibly suffer the symptoms you describe.

I am not really familiar with the series 2 fuse boxes, but i presume that the instructions that Dave gave to you regarding the correct point to take the new feed are correct, and in any case this is not the cause of your problem.

Dave's instructions (as I recall them) were excellent; unfortunately, I cannot refresh my memory, because I cannot find the post on this site, so I think he must have emailed his instructions to me and I have subsequently misplaced his email!

The only thing that i would like to change is to add an in-line fuse after the splice, in order to prevent meltdowns in the future.

I will certainly do that as and when I succeed in fitting a new feed that does not earth!


I hope that this helps.
Click to expand...

Thank you for your help
 
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