MG Midget Forum

Sending Unit Not Working Properly

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krim07 Avatar
krim07 Robert Schofield
Vine Grove, KY, USA   USA
I had put a new fuel tank and sending unit on my 1971 Midget. The old tank had a screw in sending unit and the new tank has a screw on one; otherwise, they looked the same. However, now with all the new stuff on my fuel gauge does not register anything below half full. The gauge works fine from full to half full, but the needle does not go below half full.

Is my problem the wrong or a faulty sending unit, the sending unit's flow arm needs to be adjusted (bent), or there is something else I may have missed?

Would one of those new aftermarket plastic units, which are reputed to be better have been a better replacement choice?


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bev sleet Avatar
bev sleet Bev S
Raunds, Northamptonshire, UK   GBR
If it's a new sender unit my guess is a bad earth, the sender has to be earthed to the tank and the tank has to be earthed to the car via the mounting bolts, clean area on the tank where the bolts go until it shines, just one will do.

Kerr Avatar
Kerr Platinum Member Norm Kerr
Ann Arbor, MI, USA   USA
I had the same problem, put in a new sender and the gauge worked (so the ground was ok), but it would register only down to a little below half, when the tank was actually completely empty (ask me how I found out).

What I did was mark that position with a white paint pen, and then everything was ok (my needle only used a portion of the gauge, but otherwise was displaying relative amount of fuel).

I had always wondered if I could simply adjust the zero position of the gauge by the screw on the back, but I never bothered because the paint line worked.

Years later I replaced the tank and sender and this time I checked everything before assembly (run a jumper to/from the sender and stroke it while watching the gauge needle) to confirm the new sender and old gauge were getting along, and also checked the new sender stroke in the new tank (peering in through the filler hole) to make sure the float arm wasn't going to interfere with anything through its full stroke.

This time my gauge reads correctly.

Not sure if my little story will help or not! Hopefully it will.


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krim07 Avatar
krim07 Robert Schofield
Vine Grove, KY, USA   USA
Thank you for the benefit of your wisdom and experience. Right now it works; when the needle hits half-full, I need to find a gas station. That will have to be how it is for now. I might replace it later on.


Floydinit Avatar
Floydinit Bob Rank
Waldorf, MD, USA   USA
1972 MG Midget MkIII "Silver Ghost"
1994 Chevrolet Silverado 2500 "Blue Beast"
1995 Chevrolet Corvette "Babs Toy"
I installed a new tank complete with sending unit.
Then one day I ran out of gas at 1/4 tank so I pulled the tank and used a ohm meter and found it was not reading empty so I had to adjust the float arm until empty actually reads empty.....Bob

littlecars Avatar
littlecars David Bassett
Nashville, TN, USA   USA
1965 Chevrolet Corvair "Ski Team Transport SOLD!"
1965 MG Midget MkII "Buffoon"
1966 MG Midget MkII "Swiss Cheese...SCRAPPED"
1970 Triumph Spitfire MkIII "Tamara's Turd... SOLD!!!"    & more
I've done the Norm Kerr workaround on one of my 1974's. I was able to get a relative full, 1/2 or empty reading from a full tank of gas. I got used to that white paint mark at the 12 o'clock position on the gauge face.

krim07 Avatar
krim07 Robert Schofield
Vine Grove, KY, USA   USA
I will check the ground on the sending unit, if that is not the problem then I'll take the tank down, adjust the arm (bend it a bit) and check the gauge. Continue that process as I put fuel in the tanks while monitoring the gas gauge. If the gauge is accurate great, if not I will replace it.

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ktm Avatar
ktm Keith M
Simi Valley, CA, USA   USA
MY midget ran out of gas in the garage with 1/8 tank indicated on the fuel gauge. I found the solution on this website in the library tab. Within the library tab click on "featured articles" scroll down to CARBURETORS/FUEL. then scroll down to "how to adjust the fuel gauge sender." This article provides the correct solution using the Ohms setting on a multimeter, which eliminates wasting time and relying on guesswork. The article also specifies you DO NOT bend the float arm, you actually bend the empty and full tabs on the sender until the correct Ohms levels are reached. This required removing the sender, adjusting the tabs and reinstalling it. The fuel gauge is spot on which I know from monitoring fuel input when the fuel gauge is at a given level.


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