My Sears best front loader simply will not get my clothes clean. It kinda dampens the clothes and tosses them around for a while and spins out the quart of water it used.
My old top loader would fill with hot water so I could let the really dirty stuff soak and then run it. did an excellent job!
It has a nice prewash soaking cycle for filthy stuff, and it certainly uses more than a quart of water. It handles nasty stuff like dog beds, muddy towels, work pants with oil etc. on them and gets them nice and clean.
Sounds to me like you have a blockage in the supply hose or the intake valve. Have you had a repairman look at it?