Are there any tried and tested procedures to establish the root cause of the low fuel light not working?
If you run out of fuel, and the fuel light does not come on, the fuel light does not work. If the fuel light is always on, even with a full tank of fuel, it's faulty. Your welcome.
It could be either a faulty low level sender, a wiring problem or the fuel light bulb has blown. When my 998 was new the fuel light did not come on, I found out the hard way as it completely ran out of petrol. A new unit was fitted under warranty. I would start with a bulb and circuit check and then work my way up to testing the sender unit.
in my case i ran out of fuel and the light didnt come on. does this mean it cannot be a faulty sender unit and has to be wiring or a bulb problem?
Check the connector/wires into the fuel pump under the tank. These can come off/loose. The senders are inside the tank and are a bit crap. Usually needs a new pump assembly,as the sender on its onw rarely come up used. I never rely on mine, I set the trip each fill up.
If you have just had it serviced it's possible that the connector has not been seated properly as the tank has been off. When I put my tank back after draining it and\or for servicing I always put in enough to fuel to check and run the bike and also test that the low fuel warning light is working as it should. Really this could\should have been done at the time of service.
fair point red i will certainly mention it to geoff... hes a straight sort where is the connector located and is it a tank off job again to check if its seated?
I'm not sure checking the sender light would be considered a service item, by all-means ask. Tank off, you're looking for this, IIRC two different feeds, one for the pump the other for the sender. Should be easy to spot on the circuit diagram.
Currently red is sick and I'm waiting for a new torque wrench to turn up, hopefully middle of next week. Be good to meet before winter hits though.
unfortunately i have no idea whether it was or was not working before the fuel tank was emptied for the fuel filter replacement but ive got a way forward so all is good