Karcher pressure washer uneven pressure

[DogwoodTales]

I have a Karcher G3100XH that has developed a symptom of alternating high and low pressure.
I checked the inlet screen and it's clean. The water supply and hose hasn't changed since the last time it was working with no issues, so it shouldn't be a water supply issue.
I ran the thing without the wand and exit hose attached and it seems to have constant pressure as it shoots the water through the outlet.
I tried the wand with and without a spray head on it. Still has the issue.
I tried using a different wand, that one is from a pw that is rated for lower pressure and it worked with constant pressure, but I wasn't getting as much pressure and eventually the water was coming out of the seems of the wand, but it retained constant pressure. Using it on this pressure washer may have toasted that thing but I got the job done. 

It seems crazy to think that it's not the wand, but I'm not convinced yet as the other wand, allowing less pressure, could be holding back whatever is the issue in the pump that's causing high/low pressure whereas the wand that intended for this machine is not and so maybe there's a pressure regulator thingamjiggy (apologies for getting technical there) in there that's not handling the full allowable pressure of the rest of the system.

I called Karcher and all they did was give me the number to a service shop where I can pay someone to fix it. I need to save $ for my upcoming kitchen remodel project where I can so I need to replace whatever part I need on this thing to myself.

I've been watching a few YT videos, but so far I'm not finding my exact scenario on my model pw. It's a gas powered pressure washer and the videos I'm finding are on the electric models. I don't know if that makes a difference in the pump style.

Anyway, any ideas on what I need to do to fix this?
thanks

[MstrCarpenter]

You could be letting too much or too little water out of the nozzle.Too much and it may think there's a detergent nozzle on there; too little and it thinks you let go of the trigger. I assume you've tried different tips and checked the gun, wand, and hose for obstructions.

Just remembered. I had a problem with one where the bypass port (it's very small) had picked up a little grit. IIRC The plunger uses the pump's water pressure to push it into bypass mode, but there has to be water pressure on top of the plunger too to help the spring.

[Roly]

You could be letting too much or too little water out of the nozzle.Too much and it may think there's a detergent nozzle on there; too little and it thinks you let go of the trigger. I assume you've tried different tips and checked the gun, wand, and hose for obstructions.

Just remembered. I had a problem with one where the bypass port (it's very small) had picked up a little grit. IIRC The plunger uses the pump's water pressure to push it into bypass mode, but there has to be water pressure on top of the plunger too to help the spring.

Also check inside the wand for a screen before it goes in the metal tube.   A partial blockage will cause the pressure relief to operate.  Roly

[kencombs]

I'd first adjust the pressure relief valve to see if that changes anything. Broken spring, rusted plunger, either could be an issue.

[Woodenfish]

After using my pressure washer I use a lubricant made for the pump that purges out the water, displaces it with oil and protects the pump valves from binding due to the water. This helps these aluminum pressure washer pumps life tremendously. You can pick up these aerosol pump oil treatments at hardware stores and any home center. It’s worth giving it a shot to see if it will free up the internal water pressure regulator. All you need is a quick shot with the pressure hose removed and a rag over the outlet to catch the oil overspray.

[DogwoodTales]

After using my pressure washer I use a lubricant made for the pump that purges out the water, displaces it with oil and protects the pump valves from binding due to the water. This helps these aluminum pressure washer pumps life tremendously. You can pick up these aerosol pump oil treatments at hardware stores and any home center. It’s worth giving it a shot to see if it will free up the internal water pressure regulator. All you need is a quick shot with the pressure hose removed and a rag over the outlet to catch the oil overspray.

Thanks. I will try that. First I need to run distilled vinegar through it via the detergent tube. That's one of the suggested solutions and I just realized that I have pretty hard water here, so some things are probably getting calcified. 
I bypass the water softener to the water supply for my garden hoses, but going forward (since I have a PEX manifold system) I will move the garden hose supply line I'm using from the bypass to the main manifold (which receives the softened water) when using the pressure washer on that hose.

[MstrCarpenter]

Let us know if that works please.

[DogwoodTales]

Sure thing! It will be a minute though.
Btw I was pulling the triggers (has two) at full open. I don’t think it works at anything less.

[DogwoodTales]

Well I was all set to run distilled vinegar through the detergent intake tube when I found that the pressure washer was operating correctly and NOT losing pressure intermittently.
However, it did not appear to be drawing in the vinegar. So that's something I'll need to look into further if I want to use detergents via the dispenser. I've always just use the pressurized water to clean and rinse stuff and apply detergent separately as needed.

Since I had it out and ready to go I pressure washed the skirts at both ends of my barn with no issues. The next day I used it to pressure wash a couple of other things with no pressure issues.

It's possible that when I was having the issue the last time that my wife may have been doing laundry. The washing machine can be a water hog, so it could have reduced the water supply pressure but I'm not sure if that was the issue. I'm going to test out that theory sometime in the next week. I'll run a load of laundry and the pressure washer at the same time and see what happens.

The manuals these days don't give you a lot of information like they used to years ago. Years ago manuals assumed some mechanical aptitude of the user. Nowadays they seem to assume everyone thinks like a Tele-tubby or something like that.

[Roly]

Well I was all set to run distilled vinegar through the detergent intake tube when I found that the pressure washer was operating correctly and NOT losing pressure intermittently.
However, it did not appear to be drawing in the vinegar. So that's something I'll need to look into further if I want to use detergents via the dispenser. I've always just use the pressurized water to clean and rinse stuff and apply detergent separately as needed.

Since I had it out and ready to go I pressure washed the skirts at both ends of my barn with no issues. The next day I used it to pressure wash a couple of other things with no pressure issues.

It's possible that when I was having the issue the last time that my wife may have been doing laundry. The washing machine can be a water hog, so it could have reduced the water supply pressure but I'm not sure if that was the issue. I'm going to test out that theory sometime in the next week. I'll run a load of laundry and the pressure washer at the same time and see what happens.

The manuals these days don't give you a lot of information like they used to years ago. Years ago manuals assumed some mechanical aptitude of the user. Nowadays they seem to assume everyone thinks like a Tele-tubby or something like that.

Use the soap nozzle to draw the vinegar in.  Roly