went to drain off the diesel fuel filter on my focus 1.8 tdci, instead of the expectant water/diesel from the drain valve it started to suck in air!!
what would cause it to vacuum in the filter housing?
I have been having poor idling issues lately, maybe this has been the cause. Engine runs great, no smoke, plenty of power no hesitation. A new filter was fitted less than 10,000 miles ago. Any ideas would be appreciated.

RM, September 2013

there could be some residual SUCTION from the pupm not a problem , the other cause is a bloked fuel line proberbly closer or inside the tank the neighbour had spluttering from his 206 diesel we took the sender off the top of the tank and wraped round the pickup streiner was muck/dirt and a good helpin of diesel bug. a good clean up sorted things-also while the senders out blow back down the fuel line to the tank to clear it . at work we put adative in the fuel at servicing that kills off the DIESEL BUG. google diesel bug adative--we use EXOCET anti bug..

lee jcb mec., October 2013