Hypro Pump Losing Pressure After A Few Seconds

My first thought is you may have either a bad seal or valve in your pump. I would try to descale it first and see if that helps. If the pump valves are bad you can find out by disconnecting the Outlet hose that goes from the pump to the machine and place it in a bucket. Then run your machine at full speed for exactly one minute and see exactly how many gallons it puts out. It should put out pretty near the gpm that your pump is rated to put out. For example, 3.5 gpm. If it puts out significantly less than what your pump is rated for then you know the pump is the problem. I had this happen on mine not too long ago and found using this method I was only getting about 2 gpm instead of 3.5 that it's rated for. Bad seals or valves in the pump head cause this loss of pressure. Hypro has some very good free videos available on their web site on care and maintenance of Hypro pumps. http://www.hypropumps.com/en-us/Tools/Videos/Videos.html
If it turns out your pump is not putting out properly you will either have to get it repaired or get a repair kit and try it yourself.
I think one other possibility is your pressure regulator could need lubricating.You might want to turn the pressure regulator all the way out while the machine is running then all the way in. Then reset it to 3 or 400 psi and see if it makes a difference. It can cause loss of pressure like that too. It would help if you posted the type of machine it's on, but my money is on the pump itself needing servicing.

It would help if you posted the type of machine. If it has high and low pressure orifices I would make sure to clean those as well as any filter screens. Could be something as simple as a clogged screen on your water supply hose. Don't ask me how I learned that one. Once I had a quick connect on the front of my machine get clogged from a detergent I was using at the time and lost pressure at the wand and eventually completely lost all water flow at the wand.

The very first thing I would do with your machine after checking your filter screens is do a descale. Then, if your still having problems take that hose that comes off the pump outlet and do that test. If your pump was properly serviced 6 months ago and hasn't had that much use I doubt if that's the problem. The key words here are "properly serviced" and that means at least all new seals and valves. This test is quick and easy. It took me just a couple minutes to disconnect the hose that went from my pump outlet to the pressure regulator off and place it in a bucket. Then just turn the machine on full blast and time how much water it puts out in one minute. Then find out how much it is supposed to put out. It took me maybe 15 minutes to do this on mine. At least you can rule it in or out using this method.

You may find this video of particular interest if it turns out the problem is in the pump. This type of repair can be done while the pump is still on the machine.
http://www.hypropumps.com/FileAttachments/spray/en-us/Service_Videos/2400/Disassembly3.wmv
and this video, http://www.hypropumps.com/FileAttachments/spray/en-us/Service_Videos/2400/Assembly2.wmv
Note: I had to right click on these videos and choose, "Open in new window" to get them to play.

Agree we with wand wizard, sounds like a blockage, could be already a dump on some machines or, as on some prochems, a warn bypass manifold

make sure you got plenty of flow from the water box to the pump...make sure the screen or filter in the water box is clean...if you have a syphon system for your chemical....block it off at the pump head to ensure there isnt any air getting to the pump from a leaking hose...if you have a pulsation accompanined by lack of pressure check your check valves and their o rings for damage and wear...lack of water to the pump...is the most common...an air leak from a chemical system is the next in line...and check valves and high pressure seals...are the last..i bet...water restriction good luck