Solve Starting Problems
When hard starting is caused by failure of a fuel pump’s internal check valve, these external directional check valves can be used to restore fuel system pressure.
Repair vehicles which use a 5/16″ (8mm) or 3/8″ (10mm) fuel line without dropping the fuel tank.
FL21: 8mm (5/16″)
FL22: 10mm (3/8″)
Note: Do not use with return-less systems
To determine if the fuel system has a return line, check the following: If the fuel sender unit at the tank or the fuel rail that feeds the injectors has two lines, then generally this means that this system has a return line and the one-way check valves can be used.