Generally, the warning is "Do not connect battery voltage". The tank unit is a variable resistor connected to ground, and if it's at its low resistance end from the fuel level in the tank, the short to ground will burn out the resistor.

It could also say "Do not connect a jumper wire to both terminals" which is basically the same thing- - - -battery voltage directly to the resistor.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!