I just adjusted mine the other day. Not hard and it can be adjusted, but only so much. The first thing that you notice when you pull the sender/fuel pump assembly out of the tank is that there is only so far you can bend the arm and still have a working low fuel light. The design of the tank and the way the fuel level sensor sits in the tank, facing forward toward the front of the tank limits the amount of movement the sender has. My sending unit would cause the low fuel light come on when the sending unit put out 2.3 volts (the lower the sending unit arm sinks in the tank the more volts it puts out) but it doesn't happen instantaneously, it takes about 10 or 15 seconds before the fuel light would come on. Ideally you would want the sending unit to be putting out 2.3 volts when it is resting on the bottom of the fuel tank. But here is the problem, if you bend the sending unit's float arm too much it will hit the bottom of the tank before it can put out 2.3 volts and the low fuel light will never come on.
The way I adjusted mine was I removed the sender/fuel pump assembly from the tank. I then disconnected the fuel pump electrical connector so the pump wouldn’t be coming on when I reconnected the 4 pin connector that sends juice to the fuel pump and fuel level sender. After reconnecting the 4 pin connector I found the wire that carries the voltage coming from the fuel sender and hooked up a digital voltmeter and turned the ignition on. I then move the fuel sending unit’s float arm up and down and watch as the voltage output went up and down, the higher I lifted the arm the lower voltage output was. When I let the arm rest on the bottom of the assembly the voltage was something like 2.6 volts. I then raised the arm and slowly lower it until my low fuel light came on and this is how I determined that if the sending units voltage hit 2.3 volts or more the low fuel light would come on.. I then bent the sending unit’s float arm slightly so the voltage output would read 2.3 volts when it was slightly raised above the bottom of the assembly. I raised it slightly to take into account the thickness of the bottom of the tank where the assembly bolts to the tank so it will read 2.3 volts. After putting it all back together I filled the tank and then went for a long ride. Prior to the adjustment my low fuel light would come on at 130 miles or so. After the adjustment it comes on at just under 160 miles.
The best way to calibrate the fuel sending unit would be to have a bottom section of a beat up damaged fuel tank that you could cut the top section of the tank off and then bolt to the sender/fuel pump assembly to it. That way you could insure that the sending unit was putting out 2.3 volts as it would rest installed in your tank.
If you want to do this adjustment pick up a few things from your dealer first. 2 new crush washers for the fuel line that bolts to the bottom of the fuel pump assembly and a new rubber seal that goes between the fuel pump assembly and the fuel tank. You might also want to get a new fuel filter if you bike has some miles on it as the filter sits on the fuel pump assembly and you’ll have easy access to it while the pump is out of the tank.
One word of caution, be careful when you are removing the fuel pump assembly out of your tank. The fuel sending unit’s float arm is easy to damage and will get caught on the tank as the fuel pump assembly is being pulled from the tank.
Also, if you decide to try this you do so at your own risk. I’m not a mechanic just a guy who fixed something that Triumph should have. If you break your bike :? or burn your garage down :shock: don’t come crying to me.
