A build up of gel type stuff in the water bottle often does this. I flush it out by sticking a garden hose in the washer bottle. Give it a good swirl around until all the gunge has gone. May need to do the small pipes to the jets too if the gunge has got up them. Disconnect the pipes from the jets and backflush them. Blow through the jets if they are blocked. Refill with fresh clean washer fluid and all should be well. Unless your pump has failed, but I'm sure you'll have checked that already ..... won't you?
Chicks Fan
August 2008