When we bought the Caliber it had the ability to run from either fuel tank but you could not move fuel from one tank to the other unless the engine was running. I installed a diesel fired hydronic heater that called for the heater fuel supply to be plumbed to tank 3. This would allow us to run the heater on tank 3 and the engine on tank 4 if we desired. This winter I wanted to be able to burn all the diesel in the two tanks so we would not have to make many trips to the fuel pump. So we added a Facet Dura-lift fuel pump that is rated at 30GPH and a Racor 230R2 so we can also polish the fuel when transferring from one tank to the other.