Car Fuel Sending Units

Isn't it a drag when you suddenly run out of fuel when your gauge is saying otherwise? Don't blame the gauge just yet-the culprit might be a faulty fuel sending unit. See, the fuel gauge is just the messenger; it's what tells you your tank's fuel levels. Behind the gauge itself is the vehicle's fuel dispensing system, part of which is its sending unit. For a better understanding of how it all works, let's take a closer look at the sending unit.

The car fuel sending unit is used to measure the level of fuel in the tank. It's located inside the fuel tank of your vehicle, floating on its cushion of foam, with one end of it connected to a metal rod. The end of this rod is mounted to a variable resistor, an electrical device that can resist the flow of electricity. On the variable resistor is a strip of resistive material, one side of which is connected to the ground. A wiper slides along this strip to conduct current from the gauge to the resistor.

While different fuel sending units may vary in design, the function is always the same regardless of how far or close the wiper is to the strip. The distance between the two determines the amount of resistance. If the wiper is close to the grounded side of the strip, there is a small resistance. But if it's at the other end of the strip, the resistance is large. A small level of resistance means that the float is near the top of the tank, indicating a high amount of fuel. If the level in the tank drops, the float sinks while the resistance gets larger. All this information is then translated through the movement of the needle on your fuel gauge, indicating if your tank is full, low, or empty. See? It's not that complicated.

But the car fuel sending unit, as with any component, has its weaknesses. Sometimes, it can give inaccurate measurements. You'll notice that in most modern cars, you can still run on a pretty hefty gas supply even if the needle is really close to the empty mark-this is normal. See, as the fuel in the tank reaches its low point, the sending unit might already be sinking to the bottom, registering a false "empty" on the gauge. Blame it on the shape of your gas tank and how it works with the sending unit. However, if your gauge is giving highly inaccurate information-like if its pointed at empty when you've just filled the tank-you might be looking at a failing or entirely dysfunctional sending unit.

If you need a replacement, you can find a fuel sending unit right here at Parts Train. Keep your fuel gauge accurate and avoid the hassle of not knowing when to load up on fuel. Purchase and install only a high-quality sending unit from a source you can trust.