Need a second pair of eyes/need a new pump

Hey All,

I bought a used powerhorse (northern tool) 4/4, and it keeps having surging/low pressure. It puts out 4 gallons a minute, but the pressure seems subpar. (Need to run a get a pressure gauge, but it barely took off mold on my front walk, and my neighbors old 2200psi did that just fine awhile ago when I borrowed it.) I wanted to switch out to a 5.5/2500 pump anyway and make this my backup machine when I upgrade to a predator/udor 8.0/3000 or something along those lines. (Hopefully later this season)

My questions

  1. The engine seems to run fine. The previous owner ran SH through the pump…so Im guessing its fried. Its an AR pump. Do I need to check anything on the motor before ordering a new pump? I searched (before creating my account) and everything seemed to point to the pump. The motor starts up and runs just fine.

  2. The pump Im looking at is a GP EZ2555E 5.5/2500 psi. https://www.generalpumponline.com/product/ez2555e-pressure-washer-pump/

My motor is a dh420 powerhorse 12.5 hp, so it should work just fine, but my motor shaft is 24mm and the pump is 28.5mm so I figured I would just put an adapter on it. I know I need to match an unloader to it, but beyond that is there anything missing that I should know about? The only catch I could find is the motor runs at 3600 rpm, but the pump is 3400 rpm. Would that kill the pump?

Need pics bubby.

My bad. Does this work?

I believe this is the same model. Amazon.com

Have you checked or replaced your unloader ?

To be honest, no. Ill give that a search and report back. The previous owner had it cranked all the way to plus. Maybe I can use it on my new pump. Hadn’t thought of that. I do want to upgrade the pump for faster rinsing unless its not that much faster? I also picked up a 20" surface cleaner I want to power. From the reading I’ve done 5.5 just makes a noticeable difference.

Edit
Apparently I just read that the unloader is cast into the pump…so that maybe a no go. Ill try to figure it out tomorrow.

It does, i started out with a 4gpm and upgraded all mine to 5.5’s. I noticed immediately.

Ok, ill be switching it out then. I know I’ll make the 400ish back pretty quick.