Anyone ever have one of these go bad? What were the symptoms? Reason I bring it up the first two years I owned my 91 B2600i 4x4 the cruise control would not work. One day I decided to check the vacuum lines using a recently purchased Mazda shop manual. Everthing was fine except two. The fuel pressure regulator and the cruise control vacuum drum. Double checked the vacuum diagram and swapped the lines. Went for a drive and the cruise started working. Did not notice anything different in how the truck ran or mpg. I later tested the regulator following the steps in the manual. It seemed fine. The regulator is expensive and I'm hesitant to replace it.[/align]

 

A bad or disconnected FPR usually causes a hunting idle and decreased fuel economy, depending on how picky the computer is it might throw a code. If it was connected to manifold vacuum of some sort then it probably didn't show any symptoms.