'88 K75 Fuel question

[Westone]

I've put a couple hundred miles on my first BMW, an '88 K75s. I had surmised that one or both of the lights on the dash next to the fuel pump symbol would illuminate when the fuel got low. After a couple hundred miles on one tank, that didn't happen and I was able to add 4.6 gallons of fuel to the tank.

The reason I added fuel before the light came on is that the bike started hesitating when accelerating from a stop, and occasionally when under way. So I though it must be about empty and the fuel light is not working. However, having just looked it up on the internet, it appears the tank holds 5.5 gallons, which would have left about 9/10s of a gallon, or roughly 35 miles, at the time I filled it up. But maybe low enough that all the fuel sloshed to the rear of the tank and allowed some air into the pickup. After adding fuel it runs normally with no hesitation.

So I have two questions for experienced K75 owners:

1. Is a problem with the low fuel light indicated? Should it have been on at this point?

2. I burned at least 1/10 gallon from the time the hesitation began until I topped it off.  Is it normal for it to hesitate with a gallon left in the tank, or might that indicate an issue with the fuel pump, filter or a related item?

Thanks for the help!

[roninvt]

My light comes on when I am down 3.5 gallons, leaving a good buffer.

[TimTyler]

I had the same worry for my first few tanks of gas when I acquired the bike.

My low fuel light comes on with about one gallon remaining.

Pack a full fuel bottle, ride within a few miles of a gas station, and then run your tank dry and see if the light ever comes on.

Maybe throw in a fresh fuel filter when the tank is empty too. You just need a screwdriver.

[Chaos]

I think the most I ever got into my tank after running it bone dry was an even 5 gal, and that's with the flapper out.  Cutting out on acceleration is a sign to look for a gas station pronto.  Your light should have come on.  Another check is my light comes on sooner when the bike is left on the sidestand, but goes out after a minute of riding.  You may be able to bend the float arm to get the light to come on sooner, or there is a connection problem somewhere.

[Chaos]

and only the right light should come on with about a gallon of fuel left.  The left one is a holdover from the original 85 K100 that had  7 litre and 4 litres remaining lights, but that was dropped after 85.  The took out the light but left the hole there :dunno

[Westone]

Thanks for the replies everyone.

Chaos: Thanks for the info about how the lights work. I was thinking one or both probably should have come on. If I take the filler neck out to get at the float, is there a gasket under the rim that may be deteriorated and crumble into the tank, or need replacing should I want to replace the filler neck?