Fuel filter half full, is that normal?

[la350]

I'm still chasing the surging, bucking, hesitation issue. Starts but runs rough for a few seconds. Surges randomly under power regardless of which tank or how full. I changed the fuel filter today, fuel clean, no water and found it odd that it was only half full, is that normal? I assumed it was always under pressure and would remain full. No wet return lines to be found, any suggestions?

Lance

[Snotzalot]

How's your lift pump? That's an easy $20.00 replacement.

[cdnsarguy]

If there is an air leak into the system above the lift pump it can drain fuel off the filter via return lines.

Visit my gallery and find steel line seals pic, they go on the main inlet line to filter header and the filter out line to the IP, plus the inlet line to the IP. They are different sizes and available at most diesel shops. That's where I would start, from there we can move on... so read this page..... http://www.intellidog.com/dieselmann/idi2.htm