How does the sender unit and gauge operate

Check from the gauge circuit to the connector on the board for continuity to check the board for operational readiness. From the board connector to the electrical connector on the tank to the sending unit can be checked for continuity.

To eliminate the gauge in a failure, just ground the signal wire at the electrical connector at the tank while the key is on. The gauge should go to full. If it moves the gauge, then check the ground for the fuel pump. The power to the sending unit comes from the gauge through the signal wire and passes through the potentiometer and to ground. There will be 12 volts going in via the signal wire but only 4 volts coming out of the sending unit potentiometer going to ground, depending on how full the tank is.

The resistance of your fuel sender should match that of your gauge. For instance the resistance of the stock gauge in a 55 Chevy has a value of zero ohms when empty and 30 ohms when full. The following list is for stock gauges and some popular aftermarket brands:.

The first number represents the empty Ohm reading and the second number is the full reading. If you cannot make your gauge read anything but empty then depending on your ohm range you may have one of the following problems:. If you have a , , and Ohm sender then most likely your sender lead wire is grounding out somewhere. Or possibly the center terminal on the sending unit itself is grounding out against the body of the car. If you have a or Ohm sender then the sender may not have a proper ground or there is a break in the sender lead wire.

If you cannot make your gauge read anything but full then depending on your ohm range you may have one of the following problems:. If you have a , or Ohm sender then the sender may not have a proper ground or there is a break in the sender lead wire.

If you have a or Ohm sender then most likely your sender lead wire is grounding out somewhere. Our tanks are set up for the standard SAE 5-hole bolt pattern used by all of the aftermarket gauge manufacturers.

Please also include a picture of the top of your sending unit or the back of your gauge, and any invoice, purchase order or sales order information. Improper parts installation, or use of seals with corrosive additives or mixtures, could cause seal failure and subsequent leaks. Modification of the original part design, mishandling of product, or purchasing a sender size that will touch the tank bottom, sides or baffles, will void the warranty.

All warranty claims must be processed in accordance to our procedural outline and warranty policy. Where to send my FL sales tax certificate? Can I pick up from your location?

We do however offer free ground shipping in the state of Florida when placing an order through our online system. For troubleshooting instructions please see our Troubleshooting Guide. What outputs do you offer for the sending units? What customizations do you offer for your sending units?

Please click here to order a Gasket Mounting Kit. What is the float material? Once the pin is removed the outer casing can be removed from the sending unit. Remove any blockages from unit that may interfere with the float. Reassemble unit and reinsert into tank. A liquid level sensor allows you to monitor how much liquid is in your tank at a given time using gauge instrumentation. It also lets you know when you need to refill a certain liquid.

Some liquid level senders have more advanced features like triggering an alarm when your tank is nearing empty or having pick-up and return lines. How does a liquid level sensor work? The liquid level sensor is connected to a gauge by a sender wire.

It is also attached to a float, which moves with the liquid level in the storage tank. Together, this assembly tells your gauge how full the tank is.

The liquid level sender changes resistance, measured in ohms as the liquid level drops and the float descends. A resistor is an electrical device that resists the flow of electricity. The more resistance there is, the less current will flow. In a fuel tank, the variable resistor consists of a strip of resistive material connected on one side to the ground. A wiper connected to the gauge slides along this strip of material, conducting the current from the gauge to the resistor. If the wiper is close to the grounded side of the strip, there is less resistive material in the path of the current, so the resistance is small.

If the wiper is at the other end of the strip, there is more resistive material in the current's path, so the resistance is large. When the float is near the top of the tank, the wiper on the variable resistor rests close to the grounded negative side, which means that the resistance is small and a relatively large amount of current passes through the sending unit back to the fuel gauge.

As the level in the tank drops, the float sinks, the wiper moves, the resistance increases and the amount of current sent back to the gauge decreases. This mechanism is one reason for the inaccuracy of fuel gauges.

You may have noticed how your gauge tends to stay on full for quite a while after filling up.