Weening fuel pump

[Capt. Mark]

I have a Volvo 5.0 SI-BF s/n 4012082706 Prod. #3869135 The fuel pump started (I was told the word is) weening like it's not getting fuel. The motor runs fine at faster speeds and gas flows freely out of the fuel line when removed. Changed the water seperater/filter and even put on a brand new pump...still weening. It starts right up in the morning but after running for an hour or two it takes about ten seconds of cranking to start. Tks......