jbarzelatto > It is weird bro. I can't really tell you what the answer is. In running Meth for several years, I would have 1-2 month periods that it would be at %90 percent or below. Then out of no where, it would go back to 100% on its own -- no rhyme or reason. I learned to deal with it over time. I'm freakin' OCD man, when I tell you that I tried EVERYTHING -- believe me.
One thing I would recommend, if it really bothers you, is to clean out the system well and reinstall the line. One thing I found, is that the BMS tank (or any tank) needs to be cleaned thoroughly before install. It sometimes has plastic shavings inside that can clog the line/system. Another thing I did, was install filters coming out of the tank (before the main-line) and before the solenoid. I also replaced the line. I bought "Devil's Own" tubing which is very good and kink-free. Make sure your tubing is very secure and strapped down properly (free-slowing and little to no right angles). I used a shit-ton of tie wraps. Don't over tighten to the point that it constricts the line...but definitely make sure it has NO movement whatsoever -- it helps to prevent air bubbles from forming.
Post some pics of the install, pump location, tank, line...whatever you have so I can take a look. Here's an example of how I had my setup...
How did you run your line? Underneath the car or inside the cabin? Have you tested the current on the pump?