Neither Technician A nor Technician B is completely correct.
When performing a pressure bleeding procedure on a brake system, it is not necessary to pump the brake pedal several times. In fact, doing so can introduce air bubbles into the brake system and make the bleeding process less effective. Instead, a pressure bleeder is used to force brake fluid through the system while the bleeder valves are opened to allow the fluid and any air bubbles to escape.
As for Technician B, there is no need to hold the metering valve open during the bleed procedure. The metering valve, also known as a proportioning valve, is designed to regulate the pressure between the front and rear brakes, and does not typically need to be adjusted or manipulated during a brake bleeding procedure.
Therefore, neither Technician A nor Technician B is completely correct. The proper procedure for pressure bleeding a brake system involves using a pressure bleeder to force brake fluid through the system, while opening the bleeder valves to allow any air bubbles to escape. The metering valve does not need to be manipulated or adjusted during this process.