Light Aircraft Association

Hi team!

How does one discover / measure what resistance / impedance of fuel level sender I have installed in a tank, in the absence of any visible markings?

I'm after a new gauge to go with the tank/sender and a Mitchell one looks the part but comes for 0-90 ohm or 10-180 senders. I can do without the hassle of ordering the wrong one.

Regards,
Rob Swain

Rob
You will have to measure the resistance with an ohmeter most multi meters have a sutable scale Ensure the ohmeter you use is high resistance and can only pass a few milliamps not an earth tester which passes a high current.
Connect meter between earth & sender terminal measure resistance with tank empty then fill tank ,resistance will change as tank is filled, most will a low resistance when tank is full & higher resistance with tank empty but some are the other way around. You then need to find a matching indicator.

best of luck Clive

Thanks for that, Clive.

It is as easy as I wondered it might be. As the tank is empty and off the plane at the moment we'll measure it with the tank right way up, and again upside down to get the float to go to the top of its range.