Club 80-90 Forums

Had a bit of a scare this evening. I was adjusting the automatic chokes on my 83 2.0L air cooled as it was running very fast on choke. I took off the air box pipes, adjusted the chokes so butterfly was almost closed at cold, tightened up and tried to start. It didn't want to start at all. I went round the back and the engine compartment was full of smoke, and the wire from the coil to the left-hand choke was glowing bright orange. I quickly turned the ignition off and the glowing and smoke eventually stopped. The wire was melted through.
I'm assuming/hoping the wire was just old and damaged, but it seems a strange coincidence that it should happen when I was adjusting the chokes. 
Could a faulty choke cause the extra load to melt the wire ? or shall I just change the wiring and try again ? If the latter, I'm tempted to put a fuse between the coil and the chokes to be on the safe side. What would be a suitable fuse rating ?
And advice would be most welcome.

Most likely the terminal touched the body

Be aware the current that melted that wire likely came through the ignition switch and every connection point between that and the melted wire. I have seen CE1 relay plates where the ignition output pin to the engine-bay was melted to the plug due to overloading. So it may be worth giving the whole circuit a check, and/or carrying a spare ignition switch in the event of problem. On the T3, the ignition switch output to the engine-bay is not fused. It uses 1.5mm wire, which suggests a nominal rating of ~15A. HTH

More likely, the choke terminal either touched the throttle linkage or the ceramic part of the choke has failed and allowed a short inside.The original wireing is only 0.5mm2 cable, it is meant as sacrificial if there is a fault, so the main wiring loom does not burn out.
 

Many thanks for the replies. Turns out BigHerb was right on the money. I found that with the choke removed, but still connected (with new wiring), the choke body was live.  I have fitted a fuse on the main ignition wire in the engine bay before the coil. I tried a 5amp, which blew. Changed it to 10amp and it seems OK.
Interesting about the wire being thin so it is sacrificial. I replaced the wire with thicker gauge, but it sounds like that was the wrong thing to do in that case.
Not sure I like the idea of the wire being the fuse, so I may re-do that new bit of wire with something thinner, and/or stick a low value fuse in the wire to the chokes.
Now to try sourcing a replacement choke, which looks like it's harder than it sounds.

I've seen them on ebay a while back. Be aware however that they are 'handed'. You cannot fit left to right, or visa versa.
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I've drawn a blank searching for these. I ordered one from Serial-Kombi, but they cancelled the order due to brexit as they have a minimum £155 order value to UK.
Part number I believe is 021129191E if anyone has any info where I might get one.

MagicWagon wrote: ↑21 Oct 2021, 06:59 I've drawn a blank searching for these. I ordered one from Serial-Kombi, but they cancelled the order due to brexit as they have a minimum £155 order value to UK.
Part number I believe is 021129191E if anyone has any info where I might get one.

I have some spares, what side is it ?

Hi Davidoft1 
It's the left side.