Quote Originally Posted by Bitsyncmaster View Post
You want to check the voltage across the two pump terminals with the pump running. If your voltage reading is low, then you can check each pump terminal using the battery ground and start tracing back the circuits to find bad connections. I would guess you can check your pump efficiency by measuring how much return fuel you get. It should be a large amount of returned fuel with the engine at idle.

As far as pump buzz. I did have the spring inside my pump pickup hose and had Hervey's heat shield keeping radiator heat off the tank and still got the buzz. So buzz is not always caused by the pickup hose collapsing. I was considering making an electronic pump controller which would hold 75 PSI primary pressure. That would eliminate most of the heated return fuel into the tank. You still need the return line for the lambda (FV) return fuel.
Thank you for your input Bitsyncmaster