I have a 1985 C30 dually with a 6.2 diesel and dual tanks. It seems to be leaking fuel from around the injector pump area and it seems to also leak from what looks to be a vent on the switching mechanism itself under the truck. When I bought the truck in October, the p.o. told me the sending unit in the drivers side tank was bad so I have never used it, but if you flip the switch to the driver side tank, it reads full. Could this have any relation to the fuel coming out of the vent??? Could the switch be bad or the mechanism itself?? What do I need to look for at the injection pump?? Thanks in advance.