Jinxx

So I have been noticing fuel pressure issue ...start the car from cold start fuel pressure is set at 48psi...volt gauge reading just past 14 .....drive for around 20 mins notice the volt gauge comes down to 14 maybe just under .....check pressure again it has dropped to 40 psi.....this has been a consistent drop of around 5 psi from start up to driving for at least 20mins.......I am running 340aerometer pump with 750cc injectors I also have the voltage stabilizer kit installed not sure where to look now