Jaguar Repair: Gas tank button, 1985 jaguar xj6, jaguar xj6

Question
Hi, im a new owner of a 1985 jaguar xj6 and im barely figuring things out. I was wondering how the gas tank button works.. Does one have to hold the button? Does the car have to be off? On? Sorry if they seem like dumb questions but id really appreciate the answer from an expert.

Answer
The gas tank switch, switches from one tank to the other. The car do not have to be off. The switch operates a valve in the trunk. With the button out the right tank supplies the fuel to the engine. Pressed in, it supplies fuel from the left tank. That switch often goes bad. Also that switch and valve often causes intermittent problems. Sam