Working pressure low, idle pressure very high

4gpm 3500psi Cat pump on honda engine.
new seal kit on pump, new unloader, black spring

red tip 40 size, working pressure is very low, release handle pump reads ~2000psi higher than working pressure, not a fast spike, but a quick build up, unloader cranked down maybe 3/4

what am I doing wrong?

You need to adjust your unloader. Adjust til the is only a few drops, or small trickle in bypass when trigger is squeezed. Gauge is not necessary.


Specific newbie questions with supporting video make me happier than I can likely convey.


And the question gets answered quickly


Dont let crypes see this. It may ruin his opinion of the forum. :smile:

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Who cares? Lol

So the gauge reading 4000-4500 on my 3500 machine is ok?

Scared me.

Gauges are not always accurate and when you adjust your unloader I doubt you’ll have that high a pressure reading. Lot depends on how much hose you are running. Adjust unloader with all your hose on the reel.

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Only 50ft of hose.

I’ll try and report findings.

This is exactly what mine was doing and I didn’t realize I was running 1,000 rpm too high. @Innocentbystander figured that one out over the phone though. The man has forgotten more about pressure washers than most of us will ever know.

It’s been almost a year, and I have another question regarding getting this unloader set correctly.

I’d like to set it according to the "turn the pressure up unitl you’re bypassing just a small amount of water’.
My question is, how do I do that “safely”?

My cat pump has a 3/4inch? hose that bypasses from near the unloader and runs over to where the garden hose would hook up. If I unhook that, won’t water just spray everywhere? Won’t the pump starve for water? Will anything high pressure be coming out anywhere that could be dangerous?

I haven’t seen any videos or anything of anyone doing it that way.
Could someone give me some pointers, I don’t want to blow up my pump or do anything unsafe.

Also, side question, I can start a new thread if it’d be helpful:
I have a 4gpm pump and size 4 tips, if I run my red tip I should be able to produce my rated 3500psi with a 4 tip on a 4gpm pump? I only get around 2000, I have just rebuilt the pump with all new seals, a 130$ investment. Do I need to drop to a smaller tip to get my pressure albeit probably losing gpm? Or maybe my unloader is set to low? Pressure gauge right after the unloader shows 2000 working psi with red tip, and climbs to 3500 when not spraying.

Thanks ahead of time!

Can you post a picture of your unloader? It should have another plug for bypass that you can pull off and put a 1/4 barb and hose for setting it. I guess you don’t really need a barb to set the unloader. It would just give you a way to direct the water flow from bypass while setting the unloader.

What size orifice does your red tip have?

I’ll grab that info when I get home, thanks!

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Sorry that took so long to get pictures, here they are.
And the red tip is a zero degree 00040