I have a Lancair 320 with a Lycoming 0-320-D3G engine.    My engine has the fuel pressure sender mounted ON the mechanical fuel pump itself.  I have noticed that lately my fuel pressure is possessed by the devil and runs from zero to 6 psi whenever it wants, in flight and on the ground.   There are no problems with the engine running and it still happily burns about 7 gallons per hour.   I replaced my fuel pressure sender because I thought with the vibrations of the engine, it could have went on the fritz but nothing changed.  My brother's RV-7A fuel pressure sender is located on his firewall with a hose running to it which I like better.   I am wondering 2 things.    First, since this is a change from what is "normal", I am wondering if my mechanical fuel pump is needing CPR.  I know they no longer sell rebuild kits due to liability so to replace the pump is only $378 at Aircraft Spruce, not a big deal.   And second, I am wondering where the fuel pressure sender SHOULD be located and exactly where on the engine it connects to - the carb itself or the mechanical fuel pump itself.  I do have the overflow tube coming out of the mechanical fuel pump and have not noticed any liquids or engine running issues.    Winter in Lake Effect Snowland of Rochester, NY provides a great time to work on airplanes.   Sure appreciate your input.   Matt Reeves N320KR