In looking at the year 2000 old body style GM S & R manuals, 6.5td fuel tank,lines & pumps with a rear factory mounted additional fuel tank, a "balance pump" with its own relay is shown in addition to the stock LH side tank supply pump & relay. Question, is how does the system work. & why is it called a "balance pump "? :confused: :help2:

As far as I know, the dual tank systems on the chassis cab trucks feed the engine (gas or diesel) from the main tank (saddle tank on drivers side), and maintained the level in the main tank by transferring fuel from the auxilary (rear mounted) tank. The balance pump and relay is for transferring the fuel. Nice idea because there is no need for a manual or electric valve to switch tanks and gage senders, but I heard that they had some problems with the float/sensor that powered the balance pump relay.