Fuel siphoning

I need to siphon a few gallons of diesel out of Mrs PDES's Evoque. However, no matter how much tube I get down the spout, it never seems to reach the diesel! So far I think I have pushed around 5 feet in and can't push any more as it feels like it has come to as hard stop.

Is there something down the fill tube that prevents the siphon tube from reaching the fuel?

Thanks

They normally have an anti siphoning device so it'll be difficult.

Haven't all cars since the early 1970'd been fitted with anti-siphon devices to prevent theft of fuel from parked cars, especially when fuel prices rocketed to 10/- a gallon.......
(For those too young to remember that is 50p for 4.54ltrs and in those days only lorries ran on diesel and you added Redex to poor quality petrol to prevent "pinking"........)
Giving my age away now.

So, how do the police manage to "dip" the tanks of vehicles for red diesel at the side of the road?

A tiny tube can normally get passed the siphoning device, enough for a sample, but not enough to siphon a tank in any reasonable time. There may be a fuel drain plug, if not you have to unclip a hose somewhere.

Take extreme care if you drain the tank!