earthig bonding

hi i have a boat with a stainless steel tank and with an f 100 on it. last week the tank leaked petrol and when i took it for repair they told me that the corrosion is due to earthing.there is an earth wire that goes from the tank to the back of the boat near the motor mounting bolts,should i connect the earth with the motor?

i`m afraid that there might be a voltage between the sender and the motor(i`m using yamaha gauge, the digital one)


Thanks,
Fabian Farrugia

[boats.net]

The ground on tank connects to negitive battery post. There may also be a ground wire between tank and metal fuel fill neck.