my fuel gauge has stopped working


New member
The gas gauge in my 2001 Sea Ray 190BR has never worked right as long as I've owned the boat. It has always read lower than it should, never quite reaching the Full mark. I'm pretty sure the tank is full because I can't squeeze any more gas into it.

Recently, the gauge stopped working completely.
Now it hangs just above empty, regardless of how much fuel is in the tank.

I probably need a new gauge or possibly a new sending unit.
How can I determine the problem using a multimeter?
Can I buy only a gauge or just a sending unit?
Are they pretty standard? Will different brands generally work with each other?
How much trouble to install a sending unit inside the plastic fuel tank?

I'm a pretty good electronics tech and a pretty good mechanic, but not real confident digging into a fuel tank.
Not sure on your particular boat. However, 9 times out of 10 it will be your sending unit in the tank.

There should be an access hatch on your deck. Typically, it's a 6" round pop-out hatch. Open it up. The sending unit will be right under the hatch. The sending unit is typically secured on the top of the tank with 6 small bolts. Disconnect the connectors, unscrew the bolts and gently remove the sending unit. Try to save the gasket. If it is a metal arm on a float, note the amount of throw from the highest point to the lowest point so that you can set up the replacement properly. Some sending units will not have an arm, but rather a float that moves up and down inside a sleeve. The principal is the same.

You can test the sending unit by hooking up an ohm meter to the lead, or leads. If only one lead, the base place will be the ground. As the arm is moved up and down, you should see the resistance change proportionally. If you don't see that the sender is bad. Make sure that the float is not damaged or soaked. Sometimes they just stick in one position due to corrosion.

Replacements are all over the Internet. The last time I replaced mine I noted that West Marine typically carries most types of replacements.
you can test the gauge by removing the wire from the sending unit. apply power to the gauge and take a 240 ohm resistor and connect it between the S terminal on the gauge and GND...gauge should show E. do the same thing with a 33 ohm resistor and it should show F.

If that's good, I'd suggest repeating the tests with the resistors at the sending unit. In other words, if the gauge proves usable, make sure the wiring from the gauge to the tank is sound...if that works, the sending unit is all that's left.

FWIW, fuel gauges on boats are notoriously inaccurate...my experience is if you need to calibrate the sending unit, worry about the E side more then the F end...
There are several videos on U-Tube that address trouble shooting and replacement of the proper component. They are quite detailed with good explanations.