264 Fuel prob.
 

I have a problem with a -82 264. The problem is that it dosent get enough fuel.. i tryed replacing the fuel regulator with another used one.. butstill the same symptoms:does not run properly on higher revs and load.. but when i try to block the retur hoseit runs good on load and high revs,but poorly on idling. I have a suspision that the pump is not perfect runningbecause it has a noticely high sound..but ofcourse, maby it canstill deliver!?
Any ideas?? or a website for diagnoses of the injection system? I have a fuel guage..
Thanks! Trond.