How to Wire a Fuel Sending Unitby Doug Leenhouts
The fuel sending unit is responsible for what the fuel gauge on your vehicle reads. There are two types of sending units; the older float style, which uses a magnet embedded in a float that resides in a tube, sending readings of how high in the tank it is floating, and there is the newer style that measures electrical resistance of the volume of fuel in the tank. Both types, however, are wired the same way.
Disconnect the negative battery terminal to prevent an accidental spark. Open the access panel for the sending unit. This is a small panel above the gas tank, and you will see the sending unit on top of the gas tank.
Cut two equal lengths of wire. One should be long enough to reach the back of the fuel gauge, and the other to the nearest ground connection. Strip about a centimeter from the ends of both of these wires, and twist the strands together.
Loosen the screws for the ground and ignition connections on the sending unit. Curl the ends of the wires, and loop them around these two screws. Securely tighten the screws with a screwdriver.
Run the wire from the post labeled "ignition" on the sender to the ignition switch. There should be a post labeled "sndr" on the switch. Solder the end of the wire to this post using silver core solder, and insulate the connection using spray-on insulation once the solder cools.
Run the other wire from the sending unit to the nearest ground connection. Connect the wire to the post using the same method used to connect the wire to the ignition switch, and insulate the connection. Reconnect the negative battery terminal.
- Never work with the fuel system near an open flame, sparks or a heating element.
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