Fuel Level Gauge & Sender

Bought this cheap universal fuel level gauge out of curiosity on how it works.

Dissecting the gauge was easy. Pry the outer ring using a screwdriver and pliers. Just be careful not to damage the glass face.

Undo the three nuts holding the needle circuit and insulating plastic.

Here's the gauge's internal circuit.

Circuit diagram.

Looking at the circuit diagram above, one is able to deduct that the ground (-) is not necessary to be connected. You can just connect (+) to ignition line from coil and (S) to fuel level sender, grounding the other end of the sender to close the circuit. To be noted is that the (-) is not connected to the gauge's body. The trimpot is there to adjust the gauge needle to show the actual fuel level.

The more current flows through the electromagnet coil inside the gauge, the closer the needle will point to Full. Without any current, the needle rests on Empty. This means your fuel level sender float should have high resistance on Empty and low on Full. I decided to check whether this is the case with my fuel level sender.

Charmant's fuel sender is confirmed to be the same as KE70's. Confirmed? Yes, i wrote about this earlier.

Here's the connector on the sender. There are two pins. One goes to the gauge and the other gets ground.

Part number on the float.

So, did it pass the test? "Tank"-fully yes.. It gave 10.3 ohm when the float's at Full position and 113.1 ohm at Empty. This will also serve as correction to my earlier post which states that it works the other way around.

Finally, a little customizing and now i have my very own Angry Birds fuel level gauge! lol..