If you want to check the pressure while fuel is flowing, use a tee to connect the gauge and the carbs at the same time. Lots of problems show up as a loss of pressure at higher flow rates. I've even been known to use a hose long enough to bring the gauge out and prop it under a wiper, so I can read it while driving at high speed.
PS, the 'spurting' is because the pump only outputs fuel during every other engine revolution. The rest of the time, it is sucking fuel from the tank.