Ballast Resistor

[Guest]

For those who have followed the previous thread I am still having trouble getting the Magenta Marvel to start

When running it goes well but to start needs a jump lead connecting the positive terminal on the battery to the positive terminal on the coil. Without that it just doesn't produce enough voltage at the moment, but when the new coil etc was fitted a couple of weeks ago it was producing what it should I think and started ok for about 4 or 5 times.

I am wondering if it can be related to the ballast resistor.

It is a MK2 car so shouldn't have a seperate one I think but have it incorporated into the loom - am I right? Mine has a seperate one and I am wondering if there is one in the loom too.

Could having a seperate one short / burn out the coil? Any other thoughts?

[Ian Durrant]

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I had lots of trouble starting mine and eventually found the wire from the solenoid on the starter motor wasn't connected. If jumping 12 volts from the battery gets yours to start easily then I suspect you have a similar fault or a break in the wire. If the ballast resistor was faulty it would start then die as you released the key.

A MK2 should have the ballast incorporated in the loom, but if this burns out or gets an internal break its common practice to replace it with a ballast resistor from a MK1.

Hope that helps
Ian

[Ian Durrant]

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Having re-read your post I see what you mean. Yes if you have a working ballast resistor wire and a Ballast resistor and both wires are live and connected to the coil it will mean the coil is over voltage and could damage it. However if the coil were faulty I doubt that jumping a cable to it would help unless the ballast bypass circuit was not working.

[Guest]

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Cheers Ian. The solenoid on the starter is actually a bit loose and was indentified as a problem by the garage before and they did some sort of "fix" on it.

If that were the root of the trouble on its own do you think the bypass method would overcome it?

I am favouring the idea of two ballast resistors as a possible. The bypass system that seems to work cuts out either BR from the starting process as far as I can see - not that I know much about electrics!

[Ian Durrant]

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A double ballast system arrangement could (would?) damage the coil. However, I don't think that would necessarily be overcome by bypassing them with a fly lead. its much more likely that you have no bypass happening when the ignition switch is in the start position, and that is corrected when you use a jump lead as a bypass.

It is just possible that you have both problems. A new coil makes the car easier to start (though I would think still difficult in the cold) until it fries because its getting too much voltage then it becomes impossible to start until the coil gets the correct voltage. I really think that's a long shot though.

Do you have a wire from the ballast resistor to the +ve on the coil and a white and pink lead also to the +ve of the coil?

[alistair260661]

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why don't you just check the voltage between the back of the tacho and the coil wire (sorry can't remember the wire colours).

This will tell you if you do have an active resistor in the wire - it will show between 6-9 volts. You must be getting a voltage if your tacho is working.

I had a similar issue but mine was no resistorsymptom being burnt out coils (a 6/9 volt one doesn't like 12 volts - gets very hot and fails - intermittantly). It seems someone previously had put in electronic ignition (which requires 12 volts), but put it back to points before I got it - but I didn't know that..... Do you have electronic ignition?

[Guest]

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Hello Alastair,

When you say tacho do you mean speedo or rev counter? I have a working rev counter but not a working speedo. As background to that, when Favershams did the Rover conversion back in 2001 no speedo drive was fitted to the gearbox (a brand new GM 180 supplied by Rimmers) but I have finally sourced a drive from an 80's big Vauxhall that I am told is right for the 180 - it will probably need to calibrated properly but we will see.

Back to this, the coil is a brand new 12v one from LD Parts and I don't have electronic ignition. Instead its got a Mallory twin point dizzy from which the cap, points and condensor have been replaced as part of this process.

Ian

[V Mad]

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Ian, if you are using a ballast, you should not be using a 12v coil. This isbecause the ballast drops the voltage, and you will not be getting the full spark energy.

Instead fit a low voltage coil designed to run with ballast or ditch the ballast resistor and feed direct from the 12vswitched supply(the white wire circuit).

[alistair260661]

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i meant the rev counter..... if it is working ok and you have a new coil you don't need a ballast resistor.

to your problem - it does sound like a poor connection either in the live lead to the starter or possibly in the earth leads engine to body, or body to battery. Test them all for voltage drop from that of the battery. You will isolate where the problem is.

If you need it I can send you a paper on measuring voltage drop or one on ballast resistors (they won't attach here)