Polo 1.4tdi struggleing to start. HELP!

Hi guys,
My 02 Polo 1.4TDi really struggles to start when there is less than half a tank of fuel in it and it has been standing for a while.
It seems to start initially then dies instantly even when i am holding the ignition on and i cannot catch it even with my foot on the floor. Then when i turn it again the engine turns over fine but it takes about 10 seconds for it to catch with a few splutters inbetween.
Originally i thought it was a glow plug problem and put new ones in and filled the car up with diesel and the problem went away. When the tank dropped below half the problems starting returned untill i filled it up 2 days later and it stopped misbehaving!
I have not yet replaced the fuel filter but thats my next idea! Anything else you guys could think of would be appreciated!
Cheers,
P.S. I'm not getting any engine warning lights so havent bothered to test it on a VagCom (which i would have to buy!).

It sounds like air is getting into the fuel supply line, or that there is a restriction. I would definately go for the filter first, as this is the most likely cause...

-Rich

If you only have problems with less than half a tank of diesel I would suspect a problem with the pickup in the tank. Perhaps there is a hole in it that allows it to suck air once the fuel level is low enough.

A cracked pickup line in the tank?