Fuel gauge problems plagued my bus for years. With the needle leaping around and randomly dropping off the scale I never really knew how much fuel I had except by filling and working out how much is used. Convinced that the sender was at fault I duly cut the inspection hole to fit a new one. While the sender isn't damped for sure and causes the gauge to leap around violently when less than a quarter full, that's normal. It tested out just the same as a replacement. So I tried a stabiliser on the gauge as it never had one - that wasn't the problem either. The gauge itself however had broken insulators causing the contacts to short out and eventually packed up altogether. I got another gauge but had second thoughts about dismantling the head unit as it might explode into a thousand million pieces. So I bought a marine multi-gauge since it had oil pressure, temp and volts as well as a fuel gauge all in one unit - perfect for the spare binnacle. Great! Except the fuel gauge (and pressure) use US standard resistance senders at 33-240ohms. Our fuel senders range 10-70ohms (or thereabouts) so I bodged things for a while by adding resistors but always wanted to get an accurate gauge. Then I found this: Basically it allows you to match any sender with any gauge. You calibrate the gauge first by pressing buttons to move the needle to min and max points - in this case full and empty - and then calibrate the sender to the gauge to show Full, 3/4, 1/2, 1/4 and Empty. This can be done with the sender or by using a variable resistor, which is what I did with a 100ohm potentiometer. It also allows you to mark a low level warning lamp to light, then flash, at two more points on the gauge. In addition there's a second connection for aux use such as a buzzer or relay, but I didn't need that. Also it has settings to damp any sudden variations in input signal. So, back to the sender and the resistance range. I'd noticed that as the lever type sender moves in an arc from horizontal to near vertical, the gauge normally drops through the first 3/4s of the gauge then slows down and actually reads 1/4 full at half a tank. I plotted an arc and then worked out resistance levels for F, 3/4, 1/2, 1/4 and E needed to get the gauge to move in a more linear fashion. Then used the variable resistor to achieve those values (to simulate sender movement) and entered these into the gadget. Then went for a drive to test it out seeing as I was around 1/4 full. Lights came on near empty. Got to a garage before I needed the Jerry can and filled up. It took 50 litres. Now my gauge reads correctly, and I get a warning light at around 12 litres left which starts flashing at around 10. It hasn't completely eradicated the sender float movement with fuel sloshing around the long thin tank when near empty but it dampens the needle movement quite well now. Great little gizmo. Can also use to match pressure gauges.