Fuel Sending Unit
When your tank is full or has enough fuel in it, the needle in your fuel gauge should move properly to indicate the amount of fuel in the tank the moment you start your vehicle. That way, you'll know when you need to have your tank refilled. If this isn't the case with your ride, it's either you have a faulty gauge or a malfunctioning fuel sending unit.
Fortunately, even an average driver with limited mechanical knowledge can troubleshoot the problem without a professional's help. This can save you time and money, considering all the hassles and the cost of taking your ride to a qualified mechanic. Here are some ways to troubleshoot problems with the fuel gauge and sending unit:
What you'll need:
- Good wire
- Jumper wire
- Phillips screwdriver
Step 1: Check the ignition switch.
Connect a jumper wire in between the ignition switch and the gauge's positive terminal. Turn the ignition on and observe the gauge. If it now works well, the culprit must be the wire between the ignition switch and the gauge. If the gauge still fails to work, proceed to the next step.
Step 2: Check the gauge for ground.
This can be done by connecting a good wire between the vehicle.s chassis and the ground post of the gauge. Again, turn the ignition on. If the gauge works this time, that means you need a replacement for the ground wire of the gauge.
Step 3: Test the ground of the fuel sending unit.
The process is pretty much similar to checking the ground of the gauge, but this time, you have to connect the wire to the sending unit's ground post. Put the ignition to the "On" position once again and see how the gauge reacts. If it works, it is the ground wire of the sending unit that needs replacement.
Step 4: Examine the float of the sending unit.
If all the above-mentioned checks didn't do any wonder, the culprit might be the float. To check its working condition, you have to take the fuel sending unit out of the tank by unscrewing the five screws that hold the tank in place. Once the sending unit is out, connect the good wire between the unit's positive terminal and the spot labeled .sndr. on the gauge. With the ignition on, tilt the sending unit to make the float move up and down. If the needle also moves up and down as you tilt the sending unit, it clearly indicates that the wire between the gauge and the sender's positive post is not working.
Step 5: Check the fuel sending unit for any change in resistance.
To do this, connect the positive lead of the multimeter to the positive post. Then, attach the negative lead to the flange of the sender. Tilt the sending unit again so the float will move up and down. Check the meter to see if it reads any change in resistance. Keep in mind that a fuel tank will yield lower resistance than an empty tank.
While the fuel sending unit is out of the tank, it is wise to also check the gasket for wear. If it's already worn out, replace it before putting the sending unit back into place.