Pressure washer pump zwd4040 wont kick down - Comet GXD2527G Pressure Washer Pump

Hi David,
The first thing I would check would be water level in all the toilet tanks on this system. If the level is too high in any one of them you may be getting a very slight amount of water overflowing into your toilet which could cause the pump to kick in as described.
If the water level is clearly below the the top of the overflow tube. If that is not the problem I would then check to see that you have the correct adjustment on the high/low pessure setting screws. It is important that there is sufficent pressure differences between the two or it will behave as described. Another possibility is the air pressure level in your pressure tank. Make sure it has adequate pressure as per manufacturers instructions. Finally if none of the above were the problem I would invest in a LINEAR one way valve (about $25.00) and install that between the pump and your pressure tank.
If your problem is still un-resolved then you do have a leak somewhere and will have to track it down... hot water tank, dish washer, clothes washer....
Good Luck
Alan

Check oil level may be low

sounds normal. Unloader opens because pressure is too high. Pressure goes down and unloader closes. Pressure builds and the unloader opens again Leave it running like that and the water will heat up. If you have a thermo valve it will protect you a little. One of the fastest ways to destroy your pump is to let it run for long periods without using it.

Make sure you are holding the trigger and water is spraying while you are trying to start it, otherwise pressure will build up in the pump and it will kick back.

if there is water pressure still hooked up then pump is primed and a sensor { that kicks the idle down when not pulling the trigger} is restricting the fuel flow. see if problem continues without pressure

If you take the valve body on the pump apart very carefully you may found a broken return spring or a blown out rubber o-ring if the engine runs but the pump doesnt pump high pressure check your pressure relief valve sounds like its stuck open.

sounds like something is siezed in the pump

Make sure that the tip of the head is not damaged, or missing anything.
Sometimes, there can be a pressure leak from the tip of the lance, inhibiting the pump from kicking in properly.
Hope that helps.

check the coupling or the belt between the engine and pump. unsure which this washer uses. the pump may also have failed, usually it is the coupling or belt broken or slipping

aftermarket oil will be fine just use same grade of oil,all manufacturers want that extra kick,