S max fuel filter problems

[Mrecht]

Hi everyone I'm new to this club so just bare with me lol. I have a 2008 s max 2.0tdci so every couple of months I'm having to put a new fuel filter on my car as the fuel drains back within a hour or so, once I've replaced the filter the car runs perfect for a couple months then suddenly doesn't start, I pump fuel through and it runs fine till I leave it for a hour then it won't start, but if I replace filter then all good. What do people think could be causing this? It's been to a ford garage with no faults found, they said I should replace the filter housing but surely if was that a new filter wouldn't make a difference?  The car gets used daily and always has at least 1/4 tank fuel. Thanks in advance for any help

[Westville]

A few thoughts on what you describe:

So the fuel is either leaking away somewhere or siphoning back to the tank? Yous ay a NEW filter solves the problem for a while - or is it the act of fitting a filter that actually solves it?

I don't understand why a new fuel filter per se would solve the problem? Other than it creating a new seal on the housing what else has changed? I think your garage may have suggested a reasonable course of action because if the existing filter housing has a leak (or is somehow distorted) after a while it would allow air into the system allowing fuel to leak out or be pushed back out of the filter to the tank.

Don't know specifics of your car but should there be some sort of non-return valve on the filter or its housing?

Have you got the right filler cap fitted - should it be vented to prevent a vacuum when fuel is sucked out of the tank?

Seems to me you are spending money on filters for no good reason though 

[TomsFocus]

I'd agree with the above, it's not the filter itself but the housing that's the issue here.  It's fine immediately after you've tightened it, but then over the next few weeks the heating and cooling cycles warp it again until the seal is lost.  As a free test, don't replace the filter next time, just remove the lid and then refit it as if you were changing the filter.

[Mrecht]

Found it guys it was the inlet pipe to the filter, it had been rubbing on the electrical wiring harness and created a microscopic hole. I'm guessing by doing the filter in interfered with it and sealed it temporarily. Thanks for the help guys