Cat 310 Pressure Question

[HighOctane]

Hey y'all; I was wondering what the pressure differential should be on a cat 310 when the trigger is pulled vs. released. I've got two pumps that have about a 500 psi difference - the rest of my pumps are closer to 200. I haven't noticed any issues; I set the pressure with the trigger pulled (1200) but these two just happen to be running higher (1700) when the trigger is released. All of my tips are the same and one of these pumps has a new head and unloader. Thanks for any info.

 

[CarWashBoy]

Are all the unloaders/
Pressure regulators the same brand etc? Just a thought! I have had that issue as well!

 

[HighOctane]

Are all the unloaders/
Pressure regulators the same brand etc? Just a thought! I have had that issue as well!

Yep all the unloaders are the same brand and max gpm; I did notice that some of the new ones I've ordered have an increased pressure rating. Were the unloaders the issue for you?

 

[MEP001]

There are several possibilities. You may not be making enough flow to reach 1700 PSI with the trigger pulled, but when it's released the flow drops and the pressure comes up. When you set the pressure, watch the gauge and if the needle stops increasing as you crank down, back it off until you can see the needle move as you turn it and leave it right on that edge. If you're using something like a Paraplate regulator, when they go bad they won't control the pressure correctly.

 

[HighOctane]

There are several possibilities. You may not be making enough flow to reach 1700 PSI with the trigger pulled, but when it's released the flow drops and the pressure comes up. When you set the pressure, watch the gauge and if the needle stops increasing as you crank down, back it off until you can see the needle move as you turn it and leave it right on that edge. If you're using something like a Paraplate regulator, when they go bad they won't control the pressure correctly.

Ok gotcha. I use AR North America VRT3 unloaders. When I am setting the pressure (with the trigger pulled) the needle on the gauge moves freely and will go up to 1500+. When I release the trigger, the pressure will consistently jump 500 psi regardless of the pressure I just set. Usually when these unloaders go bad I'll get a slow loss of pressure over a week or two - I keep adjusting the regulator until I'm all the way out and then I swap it for a new one. As for not making enough flow, are you talking about a potential blockage in the line? Thanks.

 

[MEP001]

There could be an issue with the pump like bad seals, your belt could be slipping, the tip in the bay washed out, or a defective check valve. A car wash pump isn't usually set up to reach over 1500 PSI because you really don't want more pressure than that or you risk a customer injuring themselves, and it's inefficient.