However, excessive fuel pressure will heat the fuel and reduced the cooling ability of the fuel. So a little extra fuel pressure is a good thing because it ensures the Bosch VP44 injection pump stays cooled and lubricated properly. Now take notice to the overflow valve is set for 14 PSI so excessive pumping of fuel does nothing for performance except create more heat in the fuel, which in turns reduces the cooling ability of the fuel and adds more stress to the lift pump. This is undocumented maximum pressure is 20 PSI. Yellow zone is a warning that you should check the fuel filter, lift pump performance, overflow valve, etc. You want the needle to stay in the green at all times. Here is a colorize fuel pressure gauge to give you a clue of the fuel pressure span you want.

It should never fall below 10 PSI at all. Normal fuel pressure should float about 14-15 PSI running down the pavement. This is for your Dodge Cummins Turbo diesel truck with a Bosch VP44 injection pump. Here is a copy of the fuel system specifications from the Dodge Factory Service Manual. Fuel Pressure Specification For Bosch VP44 Injection Pumps

Manual de bomba bosch vp44 injection