Does anyone know if the 6.2 fuel filter - the box shaped one - can work properly if it is on the suction side of the lift pump as well, or if it was only made to work on the pressure side of the pump? For the type of system i have (a two-tank set up, one with diesel and the other with svo) it is generally re-plumbed so the the fuel filter is BEFORE the lift pump, rather than after it.
But i have heard that this filter will leak, air especially, if done this way as it was designed only to be on the pressure side. I only know of one person who said this, a mechanic (who works mostly on bmw, MB, etc and not an expert per se on this engine) who did a conversion like the one i mention and could not get the vehicle started afterward due to air leaks, until he put a different filter.
Can anyone shed some light on this one?
thanks,
Paul

I think he's right, if you look at the rubber grommets on the filter, I think they're only facing one way, that is they can hold pressure, but cannot sustain vacuum.

Don't put the stock 6.2 fuel filter before your fuel pump or you will suck air!!!! The filter needs pressure to seal the seals around the tubes that go into the filter. If you bend those tubes just a micro then they will not seal in the normal position (after the pump). If you drop a complete filter assy. (with the filter installed) then it will probably leak and you will have to throw the whole thing away (from experience).