What do you need to check low pressure fuel pressure?

What do you need? I know I need a gauge. I was thinking about just using a cheap tire pressure gauge. But I really need something to stay on so we can go drive it and see. Truck is loosing power, I am thinking more that the pump is not running all the time. It had a fuel rail pressure high code last time I looked at it, we changed filters and it ran perfect now it is doing it again. but there is a check engine light now. I just hope it hasnt trashed a hp pump.