Wow! Over 4 yrs I've been messing with this thing, on and off of course.
Anyway..I've fixed it!
Symptoms were, motor pulsed when switch on and then the mcb would trip. The heater coil was blocked solid so I got a new one ages back, didn't cure it although water would now run through it but no pressure at all.fitted all new valves to the pump head, no differance, got a good used pump head, no differance. This thing is an industrial hot and cold pressure washer so worth spending some cash on it but I was up to nearly £400 by now and seriously thinking of breaking it for parts, it was doing my head in!
The pump head has two switches that operate by water pressure and control the contactor in the electrical box, when you let go of the lance trigger, excess pressure builds up very quickly closing one of the switches and removes the supply to the contactor and the machine stops.
When you pull the lance trigger again something electricery happens from the other switch and the motor starts up again.
Are you bored yet? No! OK, I'll continue.
This thing was free, didn't work, giver new nowt about it.
Turned out the two switches were wired wrong, back to front basically, only found out when I managed to get a wiring diagram and translate it from german.
Works a treat on cold but the burner wouldn't fire up. That was just a knacked fuel pump solenoid, bit pricey at £55 but that all works now. Bit smokey ill play with the burner nozzle and air settings which should cure that.
Well happy with it now.