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MG Midget and Sprite Technical - fuel gauge

hi all,
my midget does not have a voltage stabiliser and buy the diagrams it shouldnt have.should i have a bi metal fuel gauge or is this only for car with voltage stabiliser.bought a new sender and gauge registers full when empty. ? do i need to change gauge for 12v one.
thanks bob.
trebor

with the engine not running, the voltage should be stable. if the gauge reads full i would suspect the sender or wiring to be the problem
Mick - still wiring!!

new sender and old one gives same reading. wiring ok, run seperate wire with same results.been told that bi metal strip gauge is not correct one to car without voltage stabiliser fitted.is this correct.
trebor

has someone got a photo of fuel gauge from gan3 mkii midge. this is my one and i think its wrong.?
thanks bob.


trebor

I went through this a few years ago while chasing similar problems with my Lotus...

Your car should have the early meter-movement fuel gauge, the bimetallic version wasn't introduced until late 1967 with the conversion to negative earth.

The specs for the senders are:

Meter-movement (Early) Sender
14 Ohms - Full tank
258 Ohms - Empty

Bimetallic (Late) Sender
120 Ohms = full
30 Ohms = empty

As you can see, the resistance of the senders changes in reverse fashion, so mismatching the gauge and sender will give backwards needle movement, and the reading will be off by a factor of about 2. IIRC the wiring can be arranged to correct the direction of movement, but not the reading.

The voltage stabilizer is needed for the bimetallic setup because small voltage fluctuations can cause large fluctuations in the reading.

The tank senders were held to the tank with 6 small machine screws, and were interchangeable until the switch to the 6 (Imp) gal tank in 1971, for which the sender was held by a retaining ring.

- Bill
Bill Gavin

thanks bill.
trebor

Hi Bob

You posted while I was composing my post :-)

Yes, that is a bimetallic gauge and won't play nice with a '65 sender.

There appear to have been 3 varieties of meter-movement gauges fitted:

My Frogeye has FG2530/31, which is calibrated 0 - 1/4 - 1/2 - 3/4 - F.

Terry Horler's book lists 948cc Mk2 Sprites and Mk1 Midgets having FG2530/64, which is calibrated E - 1/2 - F.

Again according to Horler, the 1100cc cars onward had FG2530/70, which is also calibrated E - 1/2 - F. I'm not sure if there are any differences from /64.

Here's a photo of the FG2530/70 gauge from my early '67 Sprite.

- Bill




Bill Gavin

early gauges Jaegar??
Nigel Atkins

This thread was discussed on 08/05/2012

MG Midget and Sprite Technical index

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