Why An Air Compressor Won’t Build Pressure & How To Fix with 4 steps.

When something goes wrong with the pump, the air compressor usually does not build pressure. If you run the compressor continuously, the air pressure in the tank will reach a plateau, say 40 PSI in this case, and the compressor won’t build pressure beyond that. But there is another important reason to keep in mind.

The air compressor may not build pressure as fast if there are serious leaks in it. Stick with me through this article to learn what causes this problem, and how to fix it.

The Reasons Why an Air Compressor Won’t Build Pressure

Several factors may contribute to this, so let’s start by addressing them one by one.

  • Compressor pump leakages
  • Failure of a compressor piston seal
  • Failure of the compressor intake valve
  • Failure of the compressor outtake valve
  • Defective compressor gasket
  • A pressure valve on the compressor has failed

Troubleshooting Pump Problems

If your air compressor’s pump has problems, it will not build enough pressure. In general, I have identified 3 problems.

Faulty compressor intake valve

Air enters the pump through the intake valve and air cannot come out in the reverse direction. The valve will eventually leak air if the pump is not properly sealed. It cannot provide the pressure you need if there is not enough air in the pump.

In most cases, a failed flapper valve means a trip to the compressor repair shop because it requires the entire compressor pump to be taken apart to determine where the failure is located, and then the search for compressor parts begins.

Here’s an image of an air compressor pump that has the intake filter circled in red.

Then open the compressor, remove the intake filter, and feel around the intake port carefully. This port should be pumping air out if the intake valve is failing. Therefore, the intake valve needs to be replaced.

It can prove difficult to locate flapper valves for an older compressor, depending on its make and model. A new one can be made from the old one if needed.

Pressure valve failure in a compressor

The intake valve closes when the compressor piston moves into the compression stroke, and, almost simultaneously, the pressure valve opens when the piston moves into the compression stroke. It is harder to diagnose a compressor pressure valve failure. Compressing air is allowed into the tank through the pressure valve. If this valve has failed, air will flow into the line to the tank, but as soon as the piston moves into intake cycle, air will still flow into the piston from the intake valve, but it will also back up the line from the tank into the piston bypassing the pressure valve. A certain amount of air cycling will prevent pressure from building up in the tank.

Pull the line from the piston head while the compressor is turned off and the tank is drained. You can now start the compressor. If you are able to prevent air from blowing out the pressure port (not using your finger or hand for safety’s sake) then that is a good indication that the pressure valve has failed.

It is not a foolproof method of diagnosis, It is important to determine that the problem is not caused by the pressure valve after eliminating other possible causes. You will need to tear down your air compressor to repair or replace the pressure valve if you determine to your satisfaction that it is the failure of the pressure valve.

Pump Piston Rings Have Issues

A compressor’s pump contains pistons. There are piston rings mounted on the pistons that prevent air from leaking from the piston area. Pumps will leak air if their piston rings are damaged. Due to this, the pump cannot deliver sufficient pressure.

Problems with pump gaskets

Each pump has a different number of gaskets. Some have just one, some have two, and some have more. The first thing you should know about gaskets is how they work.

The pump consists of two parts. A part of the pump keeps low-pressure air that enters through the intake valve. The other part of the pump keeps high-pressure air in the tank. Pump gaskets separate low-pressure from high-pressure air. The gasket cannot separate air when there is a problem with it. Because of this, high-pressure air cannot enter the tank. As a result, the compressor fails to build pressure.

Do a Pump Test to Find Leaks or Any Other Problems

You can try doing a quick pump test to create a diagnosis of leaks or pump problems. Here are the steps you need to take –

  • Empty the tank by removing all the air first.
  • Close the tank’s outlet so that only air can enter.
  • After that, set your preferences
  • Record how long it takes the compressor to fill the tank.
  • The compressor will automatically shut off when it reaches the cut-out pressure.

Using our guide, you can easily identify any leak if you have found any after performing this test. If you do not find any leaks, then you should check the pump and see if it has any problems. It should be one of the above-mentioned problems if you notice pump problems

  • Connecting the intake valve properly.
  • If the piston ring is damaged, replace it
  • If the gaskets are damaged, replace them.

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