Dear all, along with my valve clearances I have taken the opportunity to replace the fuel level sender on my 748, as it previously had its original plastic nut retained sensor and I have seen these crack and dump fuel all over the rear cylinder, so it seemed sensible to replace while tank was off with the upgraded version with alloy nut from Ducati. I refitted the tank as usual...everything connected up... but... and turned the key on with kill switch off so i could test operation of the low fuel light without running the pump, and the light only faintly glowed.... I timed it and it took 17 seconds to light the lamp up brightly as normal.... I'm 99% certain with my old sensor the light would come on instantly If I was short on petrol..... can anyone confirm this before I ring Moto Rapido and tell them it's duff.....? Cheers Peter
Yes I did, but will recheck in the morning, I did run it, as I say, yes light does come on, but it starts a faint glow then gets brighter... I dont remember this with my original and I haven't changed anything else bar the sensor.
Yes it does, but it takes roughly 17 seconds to light .. I don't remember my original doing the same.... and as you need to remove the pump.assy to swap it over again to try it substitution again to check is hassle... I was just wondering if anyone is currently on reserve, and could confirm the light should come up instantly.... which is what I remember...... at £140 if its not right it's going back.....
Mine doesn't come on immediately but I have never timed it, this is with the engine running from start-up with low fuel level. When it does come on it is bright and does not increase brightness over a short space of time.
The fuel level sensor is just a switch that turns on the light when the fuel gets down to certain level. If you measure resistance across the 2 wires, with it disconnected from the bike wiring, you should read open circuit (no continuity) for a full tank and zero resistance for an empty tank (light on). Any other values would indicate a faulty sensor.
I would totally agree apart form i plugged my old one in this am and it performed similarly... perhaps its just ducati!
It's not a switch, it's a thermistor. A temperature dependent resistor. When it's cooled by fuel the resistance is about 1000 ohm so the bulb doesn't see any voltage. When it warms up because there is no fuel to cool it the resistance drops and the light comes on. It will start to faintly glow whilst it's getting warmer before coming on fully. I think 17 seconds is quite good. Mine takes a good 30 seconds.
Well that's news to me. I had assumed that it was the same set up as on the carved Supersports which were definitely a float operated switch. Will a thermistor not have problems operating properly in cold weather or in any conditions where the fuel is at air temperature?
I'm glad I could bring you some news. It does work so I'd say no, it doesn't have any problems in various conditions. Here's a picture of the component in question.
So the plot thickens on this, I tested my new sensor on my friends 1999 916 this am, and it works flawlessly, yet on my 2002 748 the light is permanently glowing when ignition is on , as the original sensor fitted to my bike still works perfectly ( only replaced to change from a plastic nut to the safer Alloy one) so it seems a compatibility issue rather than either a fault with the bike or a fault with the new sensor.... eg.... sensor works with a 99 916 but not with how a 2002 748 is wired. I know there are wiring differences as the 916 headlights for example aren't both on on dipped....where mine are ..... not that sure where to go from here... Cheers Peter
