QUESTION: I bought a truck recently and it has a good-sized pump with a four-way valve. I have always relied on gravity to off-load waste at the dump station. People tell me that if I use the four-way valve to unload my tank, I could get it done much quicker and be back on the road. Is this true? And if it is, what do I need to do to make it work? Nick ScznikSt. Louis, Mo.ANSWER: Just as your pump builds vacuum, it can also build pressure. By cranking your four-way valve handle 180 degrees and starting the pump,
