It should have an anti siphon valve and it may be just prior to them being used. The valve will be in the 90 degree elbow on the pickup. With a Puma it is on the 33 gallon belly tank center area and You may not easily be ale to reach it wiiut removing the seat pan. We have not seen one fail yet though they could. If the hose to the valve or from the tank splitter valve will siphon then you have no siphon valve. Easy check before you bust in and start tearing it down.
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