04 670 D12 mechanical fuel supply code/no start

My 04 670 with D12 has been running flawlessly. I went to start it after it had been sitting a couple hours. It cranked longer than normal before it finally started. It ran rough and set the mechanical fuel pressure code. I let it idle a couple minutes and shut it off. Now it wont start at all.

Im guessing that the fuel supply pump has gone bad. I thought it was possibly just the water separator filter clogged, but not likely since it happened so suddenly. Any ideas on what I can check that could be the problem?

 

Thanks for the reply pablo. The volvo dealer replaced the filter but that didnt fix it. It ended up bein the piece that drives the pump. The bearings went bad in it and damaged the pump. They fixed it all up for me.