QUESTION: The used truck I bought wasn't the jewel I thought it would be. I am having trouble locating my pressure relief and vacuum relief valve. I know you've touched on the subject in the past, but could you explain how they work and the best place to locate them on the truck?John Reddington
Miami, Fla.ANSWER: The pressure relief valve and the vacuum relief valve do exactly what their names imply. If your pump is in the pressure mode from the four-way valve, the pressure relief valve can be set to open when the air in the tank reaches a predetermined
