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MG Midget and Sprite Technical - Slight electrical query?

Hi all,
Now I have my 1972 mk III back on teh road, a small query has popped up.
My rev counter bounces around all over the place & my fuel gauge drops like a stone 3- 5 miles post filling up at tesco's! There are no leaks or weeps anywhere.
I'm thinking this is due to the voltage stabiliser thingy ( its a dynamo 'ed car)
Would replacing the voltage stabiliser thingy with one of the solid state devices available on ebay cure this or should I hold fire & replace the dynamo with an alternator? ( this is planned for the future once I've enjoyed a few more miles! )
Look forward to any suggestions, and as ever many thanks
Cheers colin
colin frowen

Which voltage stabiliser thingy do you mean?

Is it the little tin can under the dash which provides an approximate 10v to power the fuel gauge, or the black box under the bonnet which controls the dynamo charge rate?
Dave O'Neill2

Dave,
Colin means >>the little tin can under the dash which provides an approximate 10v to power the fuel gauge<<
Nigel Atkins

Hard to determine due to the mention of dynamo and alternator.
Dave O'Neill2

sorry I meant that's what I think Coiln is thinking of not that it's what's there or if it is/was that it would be the cause of either problems (well necessarily with the fuel gauge)

to summerise I think Colin means the 10v by his reference to what's on eBay

I also think colin has a dynamo
Nigel Atkins

Hi
Thanks for the replies so far & I'm sorry I didnt make myself clear.
Car currently HAS a dynamo
I am planning ( at some stage) to convert to an alternator.
Would this thingy :http://www.ebay.co.uk/itm/SOLID-STATE-VOLTAGE-STABILIZER-MG-midget-MGB-MGA-/130684626598?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1e6d6926a6 sort out my jumping gauges OR should I not bother with it & put up with it until I switch to an alternator?
cheers colin
colin frowen

The voltage stabilizer is only connected to your fuel gauge. It is not related to the tach.

From your description, the fuel gauge reads full for a while and then drops to zero. That doesn't sound like a faulty stabilizer (if it was faulty then the gauge would consistently read high or low, but not accurate and then nothing during each tank use from full to low). I suspect a bad sender in the tank (a portion of those windings with poor conductivity could create those symptoms).


An issue with the Tach bouncing is either sticky inside (needs a careful cleaning), or a pulse signal supply problem (check the wiring).


Norm
Norm Kerr

just for once that was how I read your first post

that solid state voltage stabiliser is one of the two I usually post a link to (I not sure if the other type, the one I have fitted, are still sold)

the voltage stabiliser only goes to the fuel gauge by all means check that it is firmly fixed with arrow pointing up and that the connections and wires to and from it are clen, secure and protected

the original style units are also know as a bi-metal instrument voltage stabilizer they stop the fuel gauge from wandering all the time with the movement of the petrol in the tank but that wouldn't explain the >>drops like a stone 3- 5 miles post filling up<< that's possibly connections or wires not being clean, secure or protected - or the sender unit is faulty

as the wire and connectors from the sender unit are under the car which means getting the car in the air and getting dirty I start checking connections and wires from the gauge to voltage stabiliser then as much as possible back to fusebox (clean, secure and protected fuses and fuse connectors are always a good idea)

that might also help with the rev counter as the green wires from VS and reve counter appear to share a double connector, that might be furred up or loose, if not check the white wire and connection on the coil and ignition switch

then if that didn't work for fuel gauge go from gauge back to sender looking for connectors particularly

wiring diagrapm is in that Driver's Handbook book :)
Nigel Atkins

This thread was discussed between 22/04/2012 and 23/04/2012

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