What should the PSI output be with no load

Hey, I finally got the craigslist Hydrotek skid (3500psi/5.5 GPM) running good yesterday but it seems the engine was not running as fast as it should and the psi at the gun (with the correct size 5.5 tip) was 3000psi with no load with 50’ of hose. When I hit the trigger it would go down to 2200-2300 psi. When I check my pressure pro 3000psi/8GPM with 150’ of hose it was 4000psi at the gum with no load and it went down to about 2500psi when it hit the trigger with the nozzle that came with it. I read somewhere that the engine should run at 3600 RPMs. Right now I don’t have anything to measure that. So my question is what psi do you think the hydrotek should be at with no load and with a load with the 50’ hose attached? Also, do the numbers sound right for the pressure pro? I know there is a drop with the hose but was not expecting a 500 psi drop. Any help would be greatly appreciated as I would like to mess with it later today.

I did get one of neighbors to check it out. It’s running at the right speed. Going to talk to Russ about it this week. I need to order some parts for it anyway.

I had very slightly loose belts one time and my pressure dropped 500 psi, I sprayed belt dressing on them and they picked up 500 psi.

Your spike in the pressure seems way to high, I have been told 600 psi is about all you want

Dave, thanks for the response. The belts on the hydrotek are definitely loose. Going to order some new ones this week. Didn’t get to mess with them much cause a cold front is rolling in tonight (down to 20). Thanks again

Sean it always good to have an extra belt or 2 for back up. You never know when a belt can pop. In your case its a good idea to order a new belt but as for the belt on the PW you may only need to tighten it up so it keeps on working and you have the new belt for back up.
We put 1000’s of hours on our machines and even with a new belt we came across unexpected belt issues so it’s always good to have back up belts at your disposal.