I recently had a problem where the window wash would just give a splurt of water then run dry for both front and back windows. It transpired that the filter in the bottom of the reservoir had become blocked with sludge! The best way to get to the tank is to remove the front under tray ( 5 screws either side just in front of the wheel arch then 3 screws along the rear of the tray that secures the tray to the crossmember ). Slide the tray back and down to remove. You can now gain access to the bottom of the reservoir on the near side of the car. The pump and outgoing connections are a push fit into a rubber grommet at the bottom of the tank and can be prised out. The filter is part of the rubber grommet and the grommet can also be prised out. It is then possible to clean the filter. I found a coating of sludge that had formed a semitransparent disc covering the filter. Now is the time to clean the bottom of the tank. I used a toothbrush to agitate the sludge the hot water to flush out the tank. Re-insert the grommet and the pump. Refill the tank. Test. Then reinstall the underskirt. There is no need to remove the wheel arch and wheel as in other fords. To remove the tank you would have to remove the bumper.

Sounds like someone has used washing up liquid in the washer bottle, you can often get away with just using hot water in the bottle to flush out the system.

Very useful post though, thanks

Sounds like someone has used washing up liquid in the washer bottle...

Agreed. I just want to emphasise what a bad thing this can be. Using screenwash, you have a biocide in the mixture,, which suppresses the growth of nasties in the bottle. Did you know that amongst heavy drivers (taxi, truck, etc) the rate of legionnaire's disease is twice as high amongst the users of water/washing up liquid than amongst the ones using those using proper screenwash.

Now, that sounds pretty dramatic, but the absolute rate is still pretty low, so it is not a big risk. But, it still seems like a slightly strange risk to want to take.