Fuel Sender Check

[Ken's 57]

Can anyone advise how to determine if the sender switch and fuel gauge are working okay? ATM the fuel gauge likes to live in between half and empty most of the time. When I fill the tank the gauge never shows full.....only about 3/4. It then gets down to its favourite position fairly quickly. Sender switches are not cheap so I do not want to part with the $$$$$ unless I must.
Cheers, Ken

[FCRB26]

I would pull the sender out and try full and empty out of the tank might have lost a cork or corroded and bent the arm could be anything..

[Errol62]

I have known the corks to become saturated with fuel leading to the symptoms you describe. Fixed by replacing with a champagne cork though not a long term solution.


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[ardiesse]

A rough-as-guts test for the gauge unit is: connect the fuel gauge to a 12 V supply (or battery), - to case, + to BAT terminal of gauge.  The gauge should read full-scale.  Now connect the sender terminal to supply -.  The gauge should read zero (empty).

For the sender unit, the magic number is thirty ohms.  Measure the resistance between the threaded terminal and the mounting flange with a multimeter while working the float arm over its full range of motion.  The resistance should vary smoothly between zero and about 30 ohms.

If you have removed both the sender unit and the fuel gauge from the car, then you can connect both units together and power the whole system up:
Battery negative to case of fuel gauge and flange of sender unit.
Battery positive to BAT terminal of fuel gauge.
Sender terminal of fuel gauge to threaded terminal on sender unit.
Work the float arm through its full range of travel and observe the fuel gauge.  Its reading should change smoothly between E and F.

Rob

[Ken's 57]

Might pull the sender switch out and test as suggested.
Thanks.