Fuel and Oil level senders

Fuel and Oil level senders

For models with digital LCD display (MFD, MFI, NGI)

Oil and fuel senders both have a float in the tank that changes the electrical resistance as the liquid level changes.

The Fuel sender uses Pink and Black wires, which are linked through the electrical box to the MFD display. The MFD provides a special low voltage on the Pink wire to the level sender. Do NOT connect the sender to 12 volt power - ever.

The sender itself provides a simple resistance change to indicate the level. 240 ohms = empty tank, while 33 ohms indicates a full tank. The fuel sender has 8 levels between full and empty.

The sender can be checked with an ohm-meter. Disconnect the Pink wire at the electrical box and measure the resistance (ohms). If the ohm measurement is way higher than 240 ohms then the wires to the sender may be damaged or the tiny fuse inside the sender may have blown.

Note: The fuel senders made from an aluminum column have an internal float. Sometimes that float gets heavy and no longer floats. If this happens, replace the float.

See also: Fuel Sender always shows Low Fuel

The Oil level sender is similar, but only provides four different levels between full and empty. 33 ohms = full, 240 ohms = empty. Blue and Black wires.

On early models with an analog fuel gauge the sender works the same way, but the fuel gauge may require a special LR-52 module with a separate low voltage output (2.5 volts?) for the fuel gauge.

Many early models only have a buzzer for warning about Low Oil level. On these models the oil sender is a simple float switch that closes the circuit when the oil level gets low.