Here's the skinny--

the fuel system pressures are set with the electric fuel pump off. When you turn on the electric fuel pump you upset the balance of fuel pressure to the rich side. Not much.

You can run the pump on if you like--just set the high fuel flow to 41.7-- 43.4 gallons per hour at 38 inches and 2700 rpm with the electric pump on. Now you're good to go "pump on" all the time.

Several manufacturers recommend that operation.

Here's an experiment.

With engine at max power in climb-- check and adjust mixture control to 41.7 plus. Pump on.

Now turn off the electric low pump. Check for a change in fuel flow.

Or if you're lucky enough to have metered fuel pressure gauge--use that.

If it drops below 41.7-- I would not make the adjustments to accommodate pump low for takeoff.

Because if the pump or electrical power to it does fail-- you can damage the engine.