The issue will more than likely be down to the Hose you are using... If there is not enough water coming through then it can't build up the pressure and keep it constant.

I had the same issue and a half press on the nozzle usually sufficed.

 

lovely,cheers mate,il go and make my ST white again

 

hmmm..still doing it....bit of a tricky one

 

any leaks coming from it at all ?

 

I'd say water pressure. Try with a short bit of hose and make sure taps full throttle

 

yeah the connection at the front is pretty tight,but it does leak a small bit of water...lady from Karcher UK said its an air block and to turn it off ect etc..but have done that..really pissing me off,bet its something simple though...

 

Is there a shampoo bottle on it? IF SO fill it up (with water if nothing else)
as it could be drawing air in from there (might be worth making sure the little pipe that joins the pump to the shampoo tank is tight and is actually in the tank.

make sure the water supply getting to it is good, and the hose isnt kinked.

if the pressure is still coming and going, then it sounds like the seals might of gone in the pump head.

 

Mine does it mate it only does it when i first use it
its like as if its priming its self then runs great after that

 

have you tried using it without it switched on for a minute or two first to get the air out .?

Mine used to do it and it was leaking from the lance atachment, i just replaced the o ring and it worked fine afterwards

 

If you have the hose lok attachment on your hose some have a cross section inside them that can stop some of the water flow ,i usually remove them

 

mine did this the other day , it came with a long thin pokey thing that ya stick down the end of the nozzle, to unblock it

as it could be a small bit of shite in the end,just try and give it a poke!!!! if ya got something long and thin lol

 

like twins said if you are using the hozelok conector with the white plunger in the centre and the red collar on the outside then this could be the problem. I just push the plunger up so the thinnest part of the neck on the plunger can be sniped and it will fall out.

greatly aids flow