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MG Midget and Sprite Technical - FUEL GAUGE

Hi all., I am sure this problem has come up before, but I cannot find any leads to it.

My fuel gauge on my GAN5 Midget is very in accurate reading half full when complety full and qurter full when empty. I have nor srarted on this proplem yet, Can anyone advise please? Many thanks in advance Bryan
B Gore

In chasing my fuel gauge accuracy issue front to back, the most gain was had by insuring a very solid ground on both ends. Good luck!
Sheldon's 74

Gday Mr Gore, these gauges are very fragile and are easily damaged when being disassembled, however notwithstanding that they are adjustable. From memory, the resistance from the fuel sender varies from approx 40 ohms (full) to 195 ohms (empty). These figures for a late model 1500. You can set it up on the bench with a 12volt supply (battery will do) and two resistors as above, then tweak it to give better readings, but be warned, not for the faint hearted. First though follow Sheldon's advice and ensure all connections are sound, I found a poor earth to the sender unit so I connected a separate earth to it from the body, this may be your problem. Also check the voltage stabiliser/regulator which may be found bolted to the back of the speedo, it should give a steady 12V.
I trolled the attached image off the web it gives some idea of how to do this without disassembling the gauge. You will have to do further research because this image may not match your gauge. Ignore the 10V ours are all calibrated to 12V as above.
Cheers Rod


R W Bowers

The voltage stabiliser doesn't actually give a steady 12v, but switches on and off to give an average 10v.

See Paul Hunt's website...

http://www.mgb-stuff.org.uk/electricstext1.htm#stabiliser

there is also a section on testing the gauge and adjusting if necessary.

Although it is essentially for the MGB, most of it is relevant to Spridgets, too.
Dave O'Neill2

hi dave this might be a question for you. my 65 fuel gauge has just started to show full all the time.i think its the one without voltage reg. when i put my hand up the back of the dash, on the back of gauge it has 2 spade terminals and 2 nuts whick i take to be the calibration points. the nut under the terminal where the live feed goes is very hot to the touch. is this right or does it sound like gauge is shorting out. have checked all wiring back to sender and sender is fairly new. the gauge is a fg 2530/70

regards bob.
bob taylor

Hi all, Dave the stabilisers are different to MGB and the GAN6200000 onwards is what I have. However I believe you are correct it is 10volts not 12, my apologies, I must have measured mine incorrectly. However the resistance values are approximately correct, they were taken off a new sender unit which came with the new tank. The old sender was working but I wanted to install a new sender to increase reliability. FWIW the old sender, just measured, is 18 ohms full and 235 empty, different to the new unit hence my need to recalibrate the fuel gauge. HTH Cheers all. PS have an idea for converting a digital oil pressure gauge to read as a fuel gauge using the original sender unit, keep you apprised
R W Bowers

Did you know you can convert a fuel gauge to a temp gauge?

A neighbour gave me a book at the w/end. MG owners club, "MG Pratical and Technical Tips, Part 1"

This is what it says. I have no idea if it would be accurate.



Lawrence Slater

Very interesting.

Can anyone tell me where my nearest BL garage is? ;o)
Dave O'Neill2

That method surely would work, but it would be prudent to test the probe in a pan of boiling water to see where "212F" is, to calibrate where that fuel gauge's needle reading would display it.


Norm

Norm Kerr

I have just re-calibrated my fuel gauge and fit a solid state voltage supply seems a lot better now


http://www.mgexp.com/article/fuel-sender-adjust.html
mark (1977 1500 Midget) Preston Lancs

This thread was discussed between 05/06/2013 and 13/06/2013

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