" Yes it is either on or off but it cycles to maintain pressure faster or slower depending on engine load. What I was getting at is any electric pump has a max flow rate, and at that point the electric motor inside it is cycling at its design limit to maintain fuel system pressure."
My understanding was that the pumps ran constantly and either delivered fuel to the injector or bled it off through a fixed- pressure relief valve. There is a single "cycle" when the key is turn on, but I thought the pump ran 100% when underway. Is that not the case?