Intermittent electrical fault

[AJLintern]

My Spit has got a little electrical problem - the temp gauge, fuel gauge, rev counter, indicators, wipers and other electrical components occasionally cease to function while driving. This can be at best irritating and at worst rather dangerous (I imagine the brake lights fail too!) The ignition light remains off though, but that might be because being electrical it stops working too! After a while everything comes back to life again, maybe a few miles later
Any ideas? I have read that gauge problems can be caused by a faulty voltage stabiliser, though that wouldn't explain why the other systems fail.

[yertis]

You need the wiring diagram - Triumph ones are easy to understand. I don't understand the rev counter packing up because it's mechanical drive, isn't it?

Triumph wiring is a bit counter-intuitive insofar as supplies to various circuits spring from unexpected places - having said that it's nowhere near as bad as for example Audi.

I suggest you start at the fuse box on the bulkhead, because you have a broad spread of affected items which indicates the fault is upstream. Also check that the fuse box is firmly clipped into the bulkhead - they have a habit of coming unclipped, then the wires rub on the bulkhead and soon you'll have a cockpit full of smoke and sparks and a burned out loom. BTDT.

[AJLintern]

I've looked at the wiring diagram in the Haynes manual, but its been a while since I did any electronics so found it a little
I think 'Fuse box' is a bit of an exageration though - there are only 2 in there! (both fine) I can only think there's a bad connection somewhere - not suprising as the car was subject to a complete nut & bolt strip down in 2000 so something must have been put back together not quite right.

[yertis]

That sounds pretty typical...

[andy007]

On my stag I had a similar problem and changed the voltage regulator, its fine now.

[maybeso]

If it's all the systems I would check not only the fuses in the fusebox are ok but also make sure that there is no significant corrosion on any of the connections, that green crap can play hell with the electrics as is is conductive when damp, but not once it dries out. if the connections are corroded clean them up and apply a little petroleum jelly before re-assembling.

[tr3a]

AJLintern said:

My Spit has got a little electrical problem - the temp gauge, fuel gauge, rev counter, indicators, wipers and other electrical components occasionally cease to function while driving. This can be at best irritating and at worst rather dangerous (I imagine the brake lights fail too!) The ignition light remains off though, but that might be because being electrical it stops working too! After a while everything comes back to life again, maybe a few miles later Any ideas? I have read that gauge problems can be caused by a faulty voltage stabiliser, though that wouldn't explain why the other systems fail.

This is definitely the fuse box, since all the components you mention are on the same fuse.

The fuse box consists of cheap, by now very old plastic, which holds some metal strips, which in turn hold the fuses. The electrical contact between the strips and the fuses depends on the integrity of the plastic, which tends to decrease with age.

The problem with the fuse box on a Spitfire is that it's an integral part of the main wiring loom and changing it without changing the wiring loom is one hell of an operation. Look under the dash at the back of the fuse box to see what I mean.
I've had exactly the same problem you describe with my Spitfire and my solution consists of a piece of paper or cardboard stuffed in the fuse box, between the plastic and the metal bit that won't reliably stay in contact with the fuse it's supposed to be in contact with. It's held for a number of years so far and I'm confident it'll hold for a few years to come. Probably long enough for the wiring loom to last until it goes up in flames through some other electrical problem.