Hi, I have a spare set of tins. I get a new paint job on the spare then change it over every couple of years. My problem is after change over I always have low fuel pressure. When I did it a couple of years ago I only had 36psi but didn't worry too much just changed the pump and regulator, problem fixed. This time I have 48psi but will change just one thing at a time to see if its a problem with drying the pump or regulator. I want nothing less than 55psi however 62psi would make me more happy. BTW I have a 2007 Fatboy with my spare set of tins being 2009 and I get the problem with the 2009 regulator or/and pump.

 

Pull the top plate off and turn on the ignition and see if fuel sprays out of the fuel line anywhere or if fuel leaks from anywhere besides the pressure relief valve. If there are no leaks anywhere I would say the regulator is bad. But if it was fine until you switched tanks I would say something is assembled wrong or damaged fuel line