Stock Lift Pump / Cummins Campaign Pump There are some serious design flaws in the stock fuel system. The stock lift pump or the Cummins Campaign pumps are both unable to supply enough fuel volume for a hungry Bosch VP44 injection pump. Part of the problem is the stock lift pump is only good for 35 GPH flow rate. However, even Bosch states that the Bosch VP44 injection pump needs at lets 70% of the fuel return to the fuel tank which is used for