Low pressure builds pressure in unit, then when I squeeze the release trigger pressure is low.....cleaned nozzle tip and ran water through pump without power to clear any air in system, but problem persists....

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.

blockage in the wand nozzle jet

pressure out is controlled by the pressure regulator unit
this is in turn governed by the condition of the tip or nozzle
if it is blocked or partially blocked ,the regulator gets the same message as if you have released the trigger and so cuts pressure from the pump by allowing water to recirculate back through the pump
so check hoses for internal collapse ( disconnect and run garden hose water through the line )
check and clean nozzle (Most probably problem)
replace pressure regulator valve. ( not often)
internal valves--- possible but unlikely until the rest have been checked

It isnt very clear your explanation of the problem but what type washer do you have first? It sounds like you have a bad unloader or need a new variable nozzle tip. Can you explain in more clear detail. Thanks

1. Hi try descaling the lance as they very easily furr up with lime scale then drain after use every time. Good luck

clean out the nozzle as there is a blockage in that or the line

HELLO THERE:
Here is some troubleshooting tips for you and a web link for you ok this should help
best regards michael
Troubleshooting Your Pressure Washer General points to check if a problem occurs

• Are the engine and fuel switches in the “ON” position?
• When troubleshooting, always check oil and gas levels.
• The oil for the pump is a 30W non-detergent mineral oil. Do Not fill over halfway on the sight glass.
• Is the water tap open?
• Check the choke and throttle levers.
• Is the correct nozzle in the lance? Is the nozzle plugged?
• Only the black nozzle is for soaping at low pressure.
• Is the water-inlet screen clogged?
• Hold the gun trigger open while pull starting the engine.
• Check for O-rings in the lance and quick couplers.
• Has the unit tipped over? Close the fuel switch and keep pull starting the engine until the excess fuel is burnt up, then open the fuel valve and try again. Some engines will need to be primed every time they are started.
• Make sure the engine is turned off after each use. It should not be left running without use for longer than 2 minutes as the pump can overheat.

Are you experiencing low pressure?

• Is there an air leak?
• Dirty pump valves?
• Check for worn pump valves or broken valve springs.
• Check for a worn out spray nozzle.
• Check for leaks in your plumping or hoses.
• Troubleshoot your nozzle, is it turned to the highest pressure setting?
• Is the unloader improperly set?
• Are the engine RPMs too low?
• Check if your water supply is sufficient.
• Check if your engine is getting enough power.

Trouble with high vibrations

• Dirty pump valves?
• Do you have a sufficient water supply?
• Is there are in your water supply?
• Is the inlet water filter clogged?
• Clogged or damaged spray nozzle?
• Make sure it has the correct fuel
• Has the choke been left on after the engine has warmed up?

If the engine won’t start

• When troubleshooting the engine, check if it's low on fuel or oil?
• Worn or dirty spark plugs?
• Is the switch in the off position?
• Is the fuel valve in the off position?
• Is the engine flooded from over choking?
• When cold starting, was the engine properly choked?

If the starter is hard to pull

• Low oil in the crankcase or pump assembly.
• Oil or fuel in cylinders (hydro locked).
• Pressure built up in the system, relieve this by squeezing the trigger.

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.

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 about a $5 (maybe) part, and it took about 5 minutes.