why won't the ballast fill?

My buddy has a 2002 Supra direct drive. It has front and rear ballast. For some reason the rear one never wants to fill all the way. It fills about 1/4 way and stops. The front fills all the way up but it only does it when it feels like it. Whats the deal? Is there a trick to getting them to fill? The pumps have been looked at and replaced, but they still don't like us..................