10 replies to this topic

[IainR]

Ongoing project now won't start, turning over well and appears to have some sparks and petrol is getting through.

Checking with a meter the voltage at the live feed to the coil only registers 4.5v with the ignition switched on (and with ignition on the pink ballast wire gets hot).

If I pull the feed off the coil the end of the cable records 12+ volts, is the coil knackered or is the 4.5v normal?

[Dan]

It will always show 12v disconnected, that's not a problem.

It should be more than 4.5v though and the cable should bot really be heating that dramatically. Sounds like you have the wrong coil fitted, possibly a 3 ohm 12v coil rather than a 1.5 ohm ballasted coil.

Tell us more about the car though, it's hard to answer questions without all the info which is why you are asked to give us the important points when you start a new technical thread. Is it a points ignition or an electronic system? What coil is fitted and what age is the Mini? Is it meant to have the ballast system or has it been added?

[dklawson]

Sounds like you have the wrong coil fitted, possibly a 3 ohm 12v coil rather than a 1.5 ohm ballasted coil.

Unfortunately, that won't explain the 4.5V or the heat. The higher resistance of the 3 Ohm coil will produce higher voltages on coil (+) and reduce the current flow more than a 1.5 Ohm coil which means less heat on the pink wire.

Regardless, the voltage on coil (+) should be somewhere between 6-9V, not 4.5V. Is this perhaps a low resistance coil from an electronic ignition or something? With the low tension wires removed, measure the resistance across the coil's low tension terminals and let us know what you find.

[Ethel]

You measure voltages across things, when you see 12 volts it's because the battery is the only component doing anything.

The pink wire has dropped 8 volts in heating itself, either it's faulty or the coil has the wrong resistance and has dropped the "electrical pressure" we call voltage, like a wide open tap on a water pipe.

[Dan]

The higher resistance of the 3 Ohm coil will produce higher voltages on coil (+) and reduce the current flow more than a 1.5 Ohm coil which means less heat on the pink wire.

Ha yeah I knew I'd get that the wrong way around trying to do the maths quickly without actually doing it! It might be the electronic coil that's been fitted then, it has a very low primary resistance. 0.8 Ohm I seem to remember.

[bmcecosse]

My TR7 uses a coil that runs at 6 volts - via a ballast wire. But in this case - that coil should be giving FANTASTIC sparks - unless it has welded the points together of course!

[IainR]

Thanks for the replies.

To give more details, my car is a 1986 City 1000E but fitted (before I bought it) with a 1098 Clubman engine.

Th resistance across the terminals is 1.3 ohms and the pink and white wire gets almost too hot to touch with the ignition on.

The existing coil is a Ducellier which has 12V cast into the end and the remains of a sticker which has the number 143 on it.

Checking Somerfords website the GLC 143 is the ballast coil for a 1275 but I don't know if that would be a problem on a 1098 engine.

Any more advice would be appreciated, thanks.

[oliver122]

i had a problem on Thursday , driving along car cut out on me , wouldn't turn over i had spark and fuel but wouldn't start , managed to get it started and drive it home , but under acceleration it would die , so then took the dizzy cap off check that , rotor arm , point all seemed fine , then i noticed that the wire had come out of the condenser put it back in crimped it up , and it fired straight in , so ive just ordered new condenser , rotor arm and points for about 7 quid as a back up i was getting 12v at the coil , was getting about 3 ohms side to side , and 4.99K ohms from side to centre. never noticed the wire heating up , but mine is running a bigger core cable then what was previously on it

[Ethel]

That's confusing then, 1.3ohms is in the right ball park for a ballasted coil, maybe a little low. GCL143 is the part number for an electronic ignition coil.

Do you get a spark at all? It might the condenser has broken down or something else shorting the points so the ignition is permanently on.

Measure the resistance of the pink ignition supply. Connect your meter between the (disconnected) wire end at the coil and a white wire at the fuse box. Ignition off or battery unhooked. You're looking for 1.5ohms (ish).


The engine is irrelevant - all you need is a coil that matches the rest of the ignition - ballasted, non-ballasted, or electronic.

[dklawson]

After re-reading your posts and symptoms I suggest you follow Ethel's advice and buy a new set of points and condenser.

You did not say how long it took the pink wire to heat up. However, if the condenser is shorted or the points are barely opening, the coil and pink wire will be carrying current all the time. The continuous current will make the wire hot. The points not opening wide enough or a shorted condenser will also make it impossible to start the engine.

[IainR]

I'll order new points and condenser and hopefully get things fitted in the next week.

The pink and white wire heats up almost instantly the ignition is switched on, I'll try testing the resistance of the wire as soon as possible.

Thanks again.