Pressure issues

[Kevin B]

Curious as to your guys opinion. I have a maxx 470, cat 3cp pump. Yesterday, out of the blue the machine just didn't build pressure. After a minute, up it came and we finished the job. Today, it did same thing. When I run it with a male qc plugged into solution hose pressure drops down to 100ish or so, in order to get working pressure of 300, I had to have pressure up to 600. Is this check valves or pressure regulator? Neither have ever been touched. 4100 hours

 

[Ron Lippold]

If I had to guess I would say its the regulator.

 

[Jim Martin]

I would lean more towards check valve is stuck or broken spring.......

 

[Dan]

Unloader or check valves.

 

[Jim Williams]

It could be sucking air in. Either a fitting or the pump seals need replacing. Or a stuck unloader.

 

[Kevin B]

Seals were done this winter, it's not sucking in air.

 

[Dan]

Im still going with unloader as my first thought. Have you tried adjusting the pressure on it when not priming?

 

[bob vawter]

solution line worn a hole at a bulkhead.....sucking air!

 

[Kevin B]

solution line worn a hole at a bulkhead.....sucking air!

it's probably the magnetic pull of the moon

 

[alazo1]

Well, I was going to say seals but you said you got them done. I have the same unit as you and had the same problem a few months ago. It was the seals.

 

[Kevin B]

Im still going with unloader as my first thought. Have you tried adjusting the pressure on it when not priming?

When not priming? If I crank regulator all the way up, it goes to 150. I have had the best luck cycling the pump on and off. I think maybe a check valve stuck open and eventually works well enough to build pressure.

 

[Dan]

When not priming? If I crank regulator all the way up, it goes to 150. I have had the best luck cycling the pump on and off. I think maybe a check valve stuck open and eventually works well enough to build pressure.

Should be easy enough to check. Generally with the unloaded when they screw up they always run pressure and don't bypass. Believe it or not I have never had a check valve fail me.

 

[Kevin B]

I have had unloaders stick in bypass, but they were the cheapo all brass units.

I still don't know if this cat pump has 3 or 6 check valves. The chemical pump has one, and it's mounted on the lower hex heads. I guess I will just start trouble shooting

 

[FB19087]

it's probably the magnetic pull of the moon

If you have air getting into the supply side you will have symptoms just as you described. Same with restrictions like clogged inline filters on the supply side.

So its not exactly a crazy idea...........

 

[Kevin B]

My experience is air into the supply side, creates cavitation and erratic pressure fluctuations. Point taken and I will check for that, but I feel it's more of a regulator/check valve issue myself. I just didn't feel like pulling check valves if its regulator.

 

[Kevin B]

Found the culprit. Spring inside regulator.

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