pressure loss

My Cat 310 Pumps are losing pressure in a few of the bays. When a HP selection is made, the pump will jump to 1200 and stay there for about five seconds. After that it drops down to around 900 and will stay there as long as the trigger is being held. If the trigger is let go then the pressure will jump back to 1200.

I took apart my pressure regulators and cleaned them up as best I could. I then replaced the gun tips in the three bays with the pressure loss. After I checked them, one bay was at 1200 and holding. The other two had moved up to about 1000-1100 but were still jumping up when the trigger was released.

I am thinking that my pressure regulators are bad in those two bays. I am a noob when it comes to dealing with these pumps, so I can use all the help I can get.

There are more likely other problems, like not enough water to the pump, sucking air from a leak or worn seals/valve o-rings. A restriction of the inlet water will usually make the pump clatter but not always pulsate roughly and may go away if rinse is selected (assuming cold water is fed with city pressure), and the pump will be smooth and quiet when the trigger is released. Air getting to the pump won't result in an immediate pressure drop when the trigger is pulled - it will lose pressure some time after and it may pulsate a little or a lot, and again will go away if rinse is selected or the trigger is released. A problem with seals will give a constant pulsation, even if the trigger isn't pulled. Check the valves first, examine the poppets (disks) for cracks and debris, replace the o-rings/backup rings if needed and coat them with Hylomar® before you reassemble it. If all the valves and o-rings look good, it's time to pull the head and check the seals.

http://www.catpumps.com/select/pdfs/5-15FSvc.pdf

I checked the valves and they all look to be fine. Are there any tell tale signs of sucking air in at a fitting? Visually, everything appears to be fine as far as that goes. I haven't noticed any wet spots or anything like that under or around the pumps. Is there anything specific I should look for on the o-rings? I am not really familiar with these pumps so I appreciate the help.

I recently had an intermitent pressure loss problem. It turned out to be a check valve was malfunctioning. It was very sporatic, so it was hard to pinpoint, but once I removed it, I could clearly tell that it was the problem. Good luck.

Is the loss of pressure accompanied by pulsation? If so, describe it as best you can, or compare it to what I listed above.

If it's completely smooth all the time, you can eliminate the regulator as the problem for certain by tying the trigger "pulled" and pinching the bypass hose from the regulator. If you can still hear or feel water flowing through it, the regulator is bad.

I am not feeling any pulsating in the gun when I am using the other two bays. I will have to check the regulator and see what happens with that. Maybe I am just blind, but I don't think I have check valves coming from my rinse tank. I know that makes no sense, but I can't find them anywhere?

Usually they(check valves) will be right at the pump. Probably right beneath them on a cat 310.

I will check again tonight, Thanks!

Have you checked the drive belts. I have had a belt slip and cause the pump not to operate at the proper rpm. It would usually only happen to one bay at a time, but it is worth a shot.

the drive belts are operating well and still have good tension on them. I am going to do a complete teardown and see if I can pick up something else I might be missing.

Sounds like not enough water going to the pump, a leak in the line
or belt slippage. Could be a check valve or the regulator though.
Connect a bay hose and gun inside the pump room on the exit side of the regulator. This will tell you if it's before or after the regulator.

Make sure to double check your tip sizes. The gpm may be greater than the pump can handle.

Mr. Bubbles- The unloader (aka the pressure regulator) is a consumable item. It wears out through time depending on the pressure you are providing to the prep guns, or any other high pressure device. Most likely you will need to replace it! It's not uncommon. When your watch an unloader operate you will see it actuate up and down with a rythem depending on the adjustments you have made to it(if it is operational). That rythem accompanied by the pulsation dampener (if you have one)tells you it's building pressure and releasing it to the by-pass valve. It sounds to me like you need to make an investment in replacement unloaders for your wash, and evaluate the psi you're running your stations at to determine customer conveinence vs. operating costs at $50.00 per unloader. THe question to ask yourself is.. How many cars has this bay done, how may operating hours on the equipment, vs. how many $$$$ have you taken in. Speed=Convienience; Quality=Value; Customer Service=Repeat Business. If you can achieve all 3; you are a GOD! Right now, pick your biggest concern! Holler' at me afterward! Then we'll talk about how to make unloaders last longer!

have you figured out your problem ? I had a simulur problem , if you haven,t got it fixed yet tell me an I.ll tell you what i found to get my bay to work?

I haven't figured out the problem yet. I pulled all of my fittings off and checked them thoroughly before replacing them. Just to have some on hand, I ordered a few pressure regulators to see if that would solve the low pressure issue. I am open for any suggestions.