Originally Posted by Diesel911

I have not bought any lately but out here the chain auto parts stores sell Goodyear or Gates fuel hose.

People in the past have used the 5/16" regular fuel hose (it is rated for diesel fuel
(SAE 30R7 is the Regular Fuel Hose)

the 5/16" Fuel Injection Hose (the Goodyear hose has a blue Viton lining and the Gates version has a brown Viton lining) or Viton hose of which I have no experience with.
(Fuel Injection Hose SAE J30R9 or 30R90 SAE 30R9--)

There is only 2 issues that I think could cause the 5/16" line not to work or a combination. One would be he is using the filter with the metal nipples and from what I have seen they have a skinnier OD on the. The other would be if the Clamp being used will not tighten down on 5/16"

The Mercedes fuel line clamps are nice but they don't have as much range as some other clamps do.