Volvo v40 d4 pro

[Wyldelee714]

Hello need advice on what the issue could be starts up fine but when I put any revs on its cuts out comes up with high fuel pump pressure too low but after been pulled in it says it getting the right pressure so I have changed fuel filter drained the tank( because of milky colour )put fresh in there's a ticking sound coming from the hight pressure fuel pump what could be the cause of this problem??
before I start pulling money out for nothing