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Sudden ignition failure - help please!


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My TR6 left me stranded for the first time in 3 years on Friday. The ignition failed suddenly whilst on the move. I coasted to a layby. I changed the electronic ignition back to the points that were on when I bought the car, but no joy. The RAC guy eventually suspected the coil and the car was towed home, so I bought a new coil. There is still no spark from the coil when I crank the engine. With the ignition on and everything connected there is around 12v on both coil terminals and at the coil lead that fits into the distributor. I've been checking previous posts but am not great with electrics. Any ideas greatly appreciated!

TIA

Phil

Edited by tr6fan
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There is only one wire to the coil live feed - does that mean I should have bought a non-ballasted coil? It is an early CR car, I believe the electrics are original, could it be a non-ballast version?

 

 

I think the ballast wire came along in 1973. If you just have a single white wire going to the coil (with a single black wire from coil to dizzy) then you need a 12v coil.

 

Stan

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Hi Phil,

you say you have +12v on both coil tags and also on the wire going to the dizzy.

This will only happen if the contact breaker is open.

Have you turned the engine, to close the contact breaker, and if so did the voltage on the -V side of the coil drop to 0V (zero) (it should do).

 

Roger

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Hi Roger

Just tried it with the points closed and got 6v on the + side and lead and 0.3v on the - side-is that how it should be?

Cheers

Phil

 

 

Try this to check the voltage to the coil.

Remove the wire from the + terminal of the coil. Put the red lead of your meter on that wire or stuck into the connector. Put the black lead of your meter on a known ground, such as the battery terminal.Then turn the ignition key to "ON". If you show 12 volts you need a non-ballasted 3.0 ohm coil.

Less than that (6 to 9+ volts), there must be an external ballast somewhere in the circuit that feeds the coil requiring a 1.5-1.6 ohm coil

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Someone already said it but I'll say it again.

 

Rotor arm.

 

The black ones made within the last 10 years are utter ****. I have had them last less than 5 miles. Sometimes they work on a cold engine and fail as soon as it warms. After many hassles with them in times past I had happily forgotten all about them having gone distributorless on the Vitesse..... and then I got the PI - and had another rotor arm die. It's being converted now.

 

However, there are now decent ones on the market that are red and are much better. Really old ones are usually ok too.

 

Nick

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Hi Phil,

it sounds like you have a ballast wire supply as the coil input (+ve) drops to 6V when the c/b is closed. However other problems may cause this low voltage and as Stan states your car wouldn't have had one originally.

 

I'm not sure how these things are actually wired up.

 

The c/b will ground (short to earth) when closed - this is good.

 

As nick states the rotor arms are an area of concern.

 

Roger

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Rotor arm, had exactly the same thing 3 years ago when out for a run came up the slip road to exit the dual carriageway and engine died. Changed back to points, no change, eventually after much head scratching changed the rotor arm and it fired up straight away.

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I'm no good with electrics - should that not happen and if so what could be causing it?

 

If you've already checked the voltage to the coil, using the - terminal of the coil as the ground and you saw the voltage come and go then you have the points doing their job.

What might cause them to fail to supply a ground, though ?

There's a braided, non-insulated ground wire inside the distributor. It can shred and become disconnected from it's terminals.

Then there is misarranging the components that make up the contact points set. in particular the tiny insulating washer.

But, you said you had this problem before switching back to points, so have a good look at that ground strap inside the distributor. I don't think you'll have trouble identifying it.

Edited by poolboy
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Hi Phil,

it sounds like you have a ballast wire supply as the coil input (+ve) drops to 6V when the c/b is closed. However other problems may cause this low voltage and as Stan states your car wouldn't have had one originally.

 

I'm not sure how these things are actually wired up.

 

The c/b will ground (short to earth) when closed - this is good.

 

As nick states the rotor arms are an area of concern.

 

Roger

 

 

 

They are not called contact breaker for nothing :D Do as poolboy suggests and pay attention to the plastic sleeve even those from a well respected suppler have been to short

Edited by ntc
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Having replaced everything I could think of with new parts, it still wouldn't fire. It did fire up however, once I realised I had put the little insulater washer on the points back incorrectly(I know, if I had a brain I'd be dangerous...)I'm going to retro fit all the old bits in sequence to find out what went wrong - I reckon either the electronic ignition module or the coil, but we'll see. A huge thank you to you all for your advice chaps - this forum is indespensible! Also a huge thank you to Rob and Richard at TRGB for their help with advice and parts - they really went out of their way and I heartily recommend them!

Edited by tr6fan
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