Gas light flashing

1980 KZ750-4 I went for a ride the other day and my gas light started flashing. So naturally I stopped to get gas. It only took 1 gallon, so apparently I didn't need gas. It has been on ever since. I checked quickly when I got home, the wires are still connected to the petcock and the instrument panel but that's as far as I got. Any ideas where to start?

Maybe a problem w the brake or brake light circuit?
On my 81 650-CSR the low fuel warning light & stop lamp indicator on the tachometer share the same lite.

If you have the Owner's Manual, it will give instructions on the functionality of the indicator lights which may lead to clues as to what to check. It could be as simple as a bad brake light bulb.

As JMKZHI says, it may be the brake-light filament is out.

The 1980 KZ 750H uses the same light to indicate fuel and brake light failure.

sorry connected to gas tank sensor not petcock. anyways the low gas indicator light does share with the brake light, which seems to be working fine and the brakes are fine....

Alright, then it's either the fuel sender is bad, or the brake light failure device is bad, or possibly a wire is broke on the brake light system.

To check, disconnect the green/white wire at the fuel tank.
If the light stops flashing then the sender is bad or shorted.

If the light keeps flashing, then disconnect the brake light failure unit. It will look like a relay with three wires: Blue, black/yellow, green/white. The light should now stop flashing.

Reconnect it, the light will once again flash. Make sure the black/yellow wire to it is grounded.

Somehow ground the blue wire using a jumper of some sort. If the light stops flashing, there is a break in the blue wire running to the bulb, or the bulb is not grounded well.

If the light keeps flashing, and the brake light filament is for sure good, probably the brake light failure unit is bad.

KZ802 wrote:

sorry connected to gas tank sensor not petcock. anyways the low gas indicator light does share with the brake light, which seems to be working fine and the brakes are fine....

Yeah, I figured you meant the wires to the sensor.
You say the brakes are fine, but what about the brake light stop lamp in the tail lite?