when you have the sender out, hook it up and fiddle the ground connection, see if you can cause a noticeable spark [assuming your gauge is OK and wired properly] .... it ain't gonna happen - the gauge passes all current to a ground on the cluster when the tank is empty or the sender ground is absent - current to the sender ground is miniscule to activate the coil that draws the needle up, and I'd doubt it could cause a spark under any but very unlikely circumstances .... the system has been in use for ages and I've never heard of a tank exploding
Bill
