Mixed pressure on cat pump

[Mdbordelon318]

I have 310 cat pump that was having low pressure issues. I checked solenoid and water supply and check valve. I found the unloaded was not working good. So I took apart n cleaned it up. Now I have 1100 lbs of pressure but when I press the gun it goes from 1100 to 800.back to 1100 when I stop.. anyone have a idea what I can check now??

 

[cantbreak80]

If you haven't replaced the spray tip recently, do so now.

When setting final pressure, always do so with the trigger pulled on the gun.

 

[MEP001]

And while you're setting it with the trigger pulled, watch the gauge. If the pressure stops going up, don't keep cranking on it.

You most likely have a problem with the pump.

 

[Mdbordelon318]

And while you're setting it with the trigger pulled, watch the gauge. If the pressure stops going up, don't keep cranking on it.

You most likely have a problem with the pump.

What kind of problem with the pump?

 

[MEP001]

Seals and/or valve o-rings.

 

[AMWeber]

I had this exact issue a few weeks ago. MEP001 is probably correct. I tried everything else then swapped the pump with a new one I had as a backup so I can rebuild the old one, problem solved. I put a gun on a short hose and came straight off the pump to eliminate all of the hoses and valves going to the bay. Then you can shoot water directly into the floor drain and watch the pump and gauges at the same time.