Low pressure in bay from a cat 310 pump

[HighOctane]

I have a problem with one of my bays that’s stumped me. When the pump is running, the pressure shows 1600 PSI, when the trigger to the gun is pulled the psi drops to 800. After changing the seals and valves with no fix, I put a brand new head on. I’ve also put a new unloader, new pressure gauge, and all new check valves on the hose. I swapped the high pressure hoses from another bay and ran them in that configuration, the problem was fixed so I know it’s before the unloader. Any ideas? Thanks!

 

[MEP001]

It's probably the tip.

 

[UtahYoutubeGuy]

I have this same issue did you try a different tip like MEP mentioned? I moved the pump to a different bay and it followed the pump which makes me think its something on the pump. Mine drops to 800 PSI just like your saying.

 

[HighOctane]

I have this same issue did you try a different tip like MEP mentioned? I moved the pump to a different bay and it followed the pump which makes me think its something on the pump. Mine drops to 800 PSI just like your saying.

It ended up being a bunch of knotted Teflon tape that had come off a fitting and lodged itself in the lines between the pump and the unloader- pretty rare issue, never seen that before. Usually if I have this problem I check the valves. If the wicks aren’t oiled enough sometimes a small piece can break off and lodge itself inside the valve or the o rings could have broken down and gotten stuck inside. If that’s not the issue then I do the seals and swap the unloader for one I know works. In your case it’s gotta be valves or seals. Replace the o-rings on the valves after making sure they’re unobstructed - there should be a white and a black one on each valve. Then swap the seals out for new ones.