I have checked the pressure at the outlet to the pressure diff valve ??mounted on the side of the metering head, I blocked off one side and measured the pressure from the side were the large red plastic fuel line fits and on the second click of the ignition key the system primes up to aprox 7 bar (100 psi) and when it starts to crank this drops to aprox 6 bar (87 psi). It holds aprox 6 bar, This drops again to 40 psi ish when it does start albeit for a second or two.