cat pump probs continue

[washman9]

have cat 5cp2120, all new valves, seals, and regulator. pump has horrible pressure with pulsation, approx 500-600psi. have switched output hoses with another bay with no change in pump. when i remove inlet hose and supply it with water directly from hose pipe it runs great, 1200 psi or more of pressure. i am at a loss and about to go crazy. could it be head wash out. could i have installed seal backwards? there are no leaks. thanks

 

[whitescout]

If you are gravity fed, make sure that your supply hose is not allowing air to be sucked in...... Yes, it is possible to suck air on the inlet side, and not have any water leaks.

 

[washnvac]

Inspect the incoming check valve. After a few years, the spring will corode a bit, and get hung up on the check. This keeps it from fully opening. When I install new checks, I also always replace the hose. I also changed my incoming to 3/4 inch from 1/2 inch. I also use a 3/4 check. This has made for a lot less issues regarding the inlet line.

 

[JustClean]

I had exactly the same problem last year and it drove me nuts. Finally I found it. It's the check valve. Mark 7 has a cone inside that got stuck. I replaced all of them with flat ones and haven't had a problem since.

 

[washman9]

i failed to mention that i did replace the inlet check valve yesterday, it did improve the quality of the pressure some but not much. in regards to the hose, mine, i believe, is 3/4 and also seems to have some sort of spring inside it to give it ridigity. can it be replace with a high quality 3/4 rubber hose. i may try this next. i also have a back up head and may end up switching heads today to see what happens. appreicate all thoughts.

 

[MEP001]

If you've fed the pump with another source and it runs fine, you've eliminated the pump as the problem. Either it's not getting enough water or it's drawing air from a leak. Replace all the small fittings for the soap and wax if they look in any way unusual. Look at the check valve you replaced - it's possible to overtighten some of them and have the nipple seat against the poppet. Try running it with no check valve and see if it works right.

If the 3/4 hose has something inside to prevent it from collapsing, it's not likely at all that replacing it will change anything.