First, determine if there are any leaks coming from the compressor tank and/or pipe fittings attached to the tank by following these steps:

• Fill the tank with as much compressed air as the pump will allow and shut the unit off.
• Using a spray bottle filled with soapy water, spray all tank welds and pipe fittings. The appearance of bubbles is evidence of air leaks. If there are weld leaks, the tank should be replaced. If there are pipe fitting leaks, attempt to tighten the fittings (do not over tighten) and repeat the soapy water test. If bubbles continue to appear at pipe fittings, remove them and apply new pipe tape to all threads.
• Next, check the tubing going from the pump to the tank, as well as the check valve (located where copper tube meets the tank) and pressure switch connectors to verify that they are all securely connected and tightened.

After correcting any of the above, run the compressor to see if this fixes the problem.

If no air leaks are detected in the above steps, the problem could be a bad gauge or pressure switch.

• Replace the tank gauge first to see if this fixes the problem.
• If not, replace the pressure switch and run the compressor to see if it will reach maximum pressure.

If the air compressor is still unable to achieve maximum pressure, inspect the pump.

• • Check the intake filter to make sure that it is clean.

While the pump is running, spray soapy water solution to the outside of it to see if there are any gasket seal leaks.

• Next, check the pump head bolts to make sure they are properly tightened.

If insufficient pressure persists, tear down the pump and inspect piston rings, cylinder and valves for excessive wear. If any of these parts are worn out, replace them and run the compressor to see if this fixes the problem.