FiTech Dual Quad

If your gauge is accurate- and I'd verify that first, then the regulator is bad or the pump is. The vacuum line will typically drop the line pressure by 10 psi. I would dead head the pump to verify it's putting out the rated pressure. You can measure the pressure directly out of the pump-anywhere before the regulator, or block the return line out of the regulator. If the pump is supplying the proper pressure, then the problem is in the regulator. If the pressure is low, check for power AND ground AT THE PUMP. If the voltage is good the pump is bad. HTH, Steve