Replaced unloader in Karcher HH2400, now unit will not start unless I depress wand handle and pull start engine.

Have you tried servicing the motor. Fresh air filter, new fuel filter and a fresh spark plug? That will help narrow down what the problem could be.

If you are unable to shut off the pressure from the wand, there may be an issue with the unloader valve that is stopping it from switching into bypass mode when the trigger wand is released. The unloader valve is designed to respond to the spike in pressure created when the trigger wand is released, and to divert the flow of water coming from the pump to bypass the pressure hose and flow back into the intake end of the pump. If the unloader valve fails to switch into bypass mode, water may continue to flow out of the trigger wand. This may also cause damage to the wand. If you are unable to shut off the pressure from your power washer, stop the engine and discontinue use immediately. The unloader valve should be removed and possibly replaced if found to be malfunctioning. The inability to stop the flow of high-pressure water from the wand can be dangerous and should be fixed before continuing to use the machine.

Hi Cliff:
My experience is that the pump pressures prevent the engine from starting, so we hold the trigger while starting.
My brother has cut a wedge of wood that he uses to jam the trigger open to bypass the problem. It can get a bit wild if the wand is not secured when the unit is started..

The pressure unloader us usually the first part/s that fail. An unloader can fail resulting in no or very low pressure or good pressure, however will not unload when trigger is released and stall the motor. Look at breakdown for your pump and determine if unloader parts are available and reasonable. If too costly to replace these parts then install an ez start valve to help start engine and tie back wand handle to deal with unloader problem (workaround). Ez start valve can be seen here:
http://www.cmcpwe.com/accessorystartvalve.html

When not in use, store washer with oil in pump to displace the water. The oil will help lube internal parts and possibly cause the unloader to begin working (if stuck due to debris/rust). You can find a gizmo to help you feed oil into pump on ebay /other web locations. Good luck with your repair.

hi
there is an unloader fitted it sounds like it is not working
check it out

Hi, Karcher calls the unloader valve a spill valve,
this is a link to a full drawing/parts listing , and your fault description might well be a sticking /seized unloader(spill ) valve hope this helps
http://www.pressureparts.com/ManualViewPage.aspx?Manual=/mmDEV/PDF/karcherparts/g2500vh.pdf

the part number is on page 9 of the drawing
spill valve 45910400
hope this helps , we usually use some good quality silicone grease to lube the valve ,

Have a helper hold the trigger of the wand open while you try it again. If it starts that way you have a sticky unloader valve in the pump. DO NOT RELEASE the trigger for more than 10 seconds if the engine continues to strain when released! If the engine doesnt run freely when you let go of the trigger, pull it again and shut down the unit!
Add some power steering fluid to your supply hose (about 3 or 4 ounces at a time) and restart the unit with the trigger pulled. Allow the oil to flow through the pump for 1 - 2 minutes for each treatment. Several treatments should make the pump and valve happy again.

Hope this helps.

Hello awcockerill:
This sounds like the bypass (unloader) valve is sticking. Here is a diagram of your machine's pump. On page 2.4 see part #1. The top of this assembly is a black plastic cover. Remove all of assembly # 1 carefully. Under that is part #8. This is the bypass valve. You need to pull this out, check that the o-rings are not bent, worn or damaged, then lube it good with a VERY VERY good waterproof grease. Re-assemble it and all should be well. The part numbers are on the diagram but where to get them depends on were you live. Karcher web site may give you a number to call. Good luck.

common for not starting unless trigger engaged as you are turning the pump as well as engine creating pressure,as for stalling pump has unloader valve which is probably in need of grease(use good silicone grease)this allows water to ciculate when trigger released.

To determine if your problem is due to an easily replaceable part, follow these steps:

1. Connect the water supply hose, the pressure hose, and the wand WITHOUT any nozzle tip.

2. Turn on the water supply, and press the trigger until water is smoothly running out of the nozzle
after any air is all purged out. Release the nozzle trigger.

3. Start the engine, and let it warm up for about 30 seconds.

4. With the engine running smoothly, press the nozzle trigger. The water should flow out of the nozzle (without the tip installed) at a faster rate, while the engine noticeably loads down as it used to do before your "no pressure" problem. If it does not load down, turn it OFF, and disconnect everything, and contact a Karcher repair facility.

5. If the engine does load down, release the trigger, and install one of the nozzle tips (not the black one).

6. Press the trigger, and the engine should load down, and you should have normal pressure from the wand. After you release the trigger and press it again, you will probably again have no pressure, and the engine will not load down. Removing the nozzle tip, pressing & releasing the trigger, and re-installing the tip should give you normal pressure again, but releasing the trigger will cause no pressure until you again remove the tip, press the trigger, and re-install the tip.

This is caused by a bad UNLOADER VALVE, which is located under a black cap with a metal button on it located on the top front of the pump. I don't know if you can purchase the replaceable parts from a Karcher repair shop, but when a neighbor & I took his washer to a repair place, it looked pretty simple to do this repair, and he was charged about $60 to replace a $5 (maybe) part, and it took about 5 minutes.