Others GX-E-CS3-I Not pumping

[Hylander]

Bought new 7/25/2025 off Amazon.
Very little use. Was filling one of my air rifles up
Took it to about 2000 psi
From empty this took about 7 minutes.
Then shut it down for zbout 20 minutes while I went in the house.
Then decided to go ahead and top it off to 3600
But I had the pump stop set at 3000
So I set it to 3600 and now it gets to about 2000 psi and stops filling. The pump is running, but pressure is not rising. Temp in my garage is probably 95 degrees. Never ran it more than
7 minutes at a time.

Any Ideas?

I brought the pump in the house to cool to see if that helps. I'll wait an hour for it to cool.
I hope it is an easy fix, I cannot afford a new pump

 

[Chief55]

Is the fan still working? See if it will start running with the bleed valve open.

Did you bleed off all the air before you shut it off? They do not do well starting up with a load on them. You leave the bleed valves open then start the compressor with no load, with it running, close the valves till you get to your fill pressure then open the bleed valves to bleed off the pressure, then turn off the compressor while it has no pressure on it. Auto stops are convenient, but I set them just a bit high as an emergency shut off and do it all manually so there is no load on the compressor when it starts and when it gets shuts off. Then let the fan run for at least 3 minutes to cool the compressor back down.

 

[FL22]

Bought new 7/25/2025 off Amazon.
Very little use. Was filling one of my air rifles up
Took it to about 2000 psi
From empty this took about 7 minutes.
Then shut it down for zbout 20 minutes while I went in the house.
Then decided to go ahead and top it off to 3600
But I had the pump stop set at 3000
So I set it to 3600 and now it gets to about 2000 psi and stops filling. The pump is running, but pressure is not rising. Temp in my garage is probably 95 degrees. Never ran it more than
7 minutes at a time.

Any Ideas?

I brought the pump in the house to cool to see if that helps. I'll wait an hour for it to cool.
I hope it is an easy fix, I cannot afford a new pump

I had something similar happen, make sure that you don’t have any o-rings leaking in the fill whip and that the bleed valve is tight.

 

[Chief55]

For some reason I can only read about half of what you wrote. I could not see anything past, But I had the pump stop set at 3000 until I highlighted it. Strange.

In that it is running, I agree with FL22 that the fill line is probably leaking. That has happened to me twice.

 

[sandog]

The CS3-I will automatically shut down for 20 minutes after 30 minutes of run time for cooling. It has to remain plugged in for the cooling fans to work.
For your unit to shut down after 7 minutes is unusual, but if the unit felt it was building up too much heat, it is probably a safeguard to prevent damage.

Make sure the rifle is cocked before filling, otherwise you could experience pressure not building up. If the rifle isn't cocked on some designs, the hammer is resting against the valve, letting air out as fast as the compressor is putting it in.

What are your deadhead test numbers ?
My 3 year old CS3-I takes 22 seconds to reach 3k, and 30 seconds to reach 3,650 psi.
When it was new it took 20 and 28 seconds to reach those pressures.


If your unit ever fails to run completely, there is a fuse that can be checked by the circuit board.

 

[Hylander]

The CS3-I will automatically shut down for 20 minutes after 30 minutes of run time for cooling. It has to remain plugged in for the cooling fans to work.
For your unit to shut down after 7 minutes is unusual, but if the unit felt it was building up too much heat, it is probably a safeguard to prevent damage.

Make sure the rifle is cocked before filling, otherwise you could experience pressure not building up. If the rifle isn't cocked on some designs, the hammer is resting against the valve, letting air out as fast as the compressor is putting it in.

What are your deadhead test numbers ?
My 3 year old CS3-I takes 22 seconds to reach 3k, and 30 seconds to reach 3,650 psi.
When it was new it took 20 and 28 seconds to reach those pressures.


If your unit ever fails to run completely, there is a fuse that can be checked by the circuit board.

Thank you,
To be honest, I have never done a deadhead check on this unit.
However, I just topped off two of my guns to 3600 psi with no issues.
I did this in the house where it is cool.
Temps here are 100*, so I'm guessing my garage is a bit hotter where the pump stopped pumping.
So for the rest of the summer, I'm airing up in the house

 

[sandog]

Using the compressor early in the day there is less moisture in the air than when it is hot.
That and the compressor running cooler in the morning is why I wouldn't use the compressor outside while it is 100 out.

Of course running the compressor inside the air conditioned house will take care of both excess heat and most of the humidity.

If you don't already have an in line moisture filter, GX Pump is now making one.
As I mentioned in the other thread, do the dead head test when you get the compressor, and write those two times on top (on a label or piece of tape).

Then when you do the test down the road you can check the new deadhead times against the old.
Significantly longer times mean you should open up the unit to check the piston ring and re-lube the cylinder walls.
Also keep records of the run time, either in a log book or with an hour meter.