Compressor runs but will not pump air into tank

If the air compressor has run to pressurize your tank, and then is shut off, it will not automatically pump the pressure up again.

The longer you use the nozzle on the air hose, a strong jet of air will become weaker and weaker. You are using up the pressure that was pumped up.

All of the air is used when there is no more jet of air from the hose. There is air inside the tank that is equal to the atmospheric pressure outside of the tank when it is considered "all out of the tank."

Do you have an air leak or the compressor may be bad and not pumping air. as it runs.

Francisco:
Could be one of two reasons. If the compressor does not reach full pressure in the tank, you have an air leak somewhere between the tank and the business end of the hose. Run the compressor and use a soap and water solution to find the leak and correct it. Don't forget to check the copper line leading from the compressor motor to the air tank. My compressor would not pump above 45 pounds, and I had to replace the valve body (on top of the cylinder) because a valve had cracked.

Air leaking air out of intake when the compressor is not running and pressure in tank indicates bad check valve. Follow the discharge tube to where it connects at the brass valve mounted to tank. This valve is a non-return valve and can be replaced with generic valve. When air blows or pulsates out of intake as the compressor is running is indication that pump has bad valves or blown gasket/ gaskets. Good luck

remove shroud and see if fan is broken but may be piston is shot

If your compressor starts with no air in the tank but pops the breaker when it restarts with pressure in the tank it is usually because the tank check valve (choke valve) is stuck open. The valve lets air into the tank while the pump is running then closes when the pump shuts off so the valve on the pressure regulator can relieve the pressure in the pump head and lines. If the valve is stuck open, the motor has to fight the tank pressure to restart. Occasionally they can be cleaned up and will work but usually they have to be replaced. The valve would be on the tank where the copper line from the pump goes into the tank. There will also be a line running from the pressure regulator on it. The Craftsman part number is A19712.

Yes it has no oil. and you need to remove the top cover and check for air leak between the pump an the tank. if you have a large leak the tank will not fill. Two screws and the cover should snap off. check copper line for blown seals.

Check the"check" valve. Usually the last part where the air line enters the tank from the compressor. With the compressor turned off and unplugged, loosen the connection between the line and the check valve. If air leaks out from the tank, the valve is defective and needs to be replaced.

if there are no leaks the head should be removed to check reed valves

The start valve gives your motor a running start before the motor begins to load as the pressure increases from an empty tank. The motor strain is more profound when there is pressure in the tank. If you plug the valve, the motor will instantly encounter a heavy load because it has to force air into a partially filled tank. This extra load without the valve will shorten the life of the capacitors and motor windings. There could be two problems with your unit that can revealed by test. What actually closes the valve is a certain volume of air produced by the compressor. If the compressor is not pumping to full efficiency or there are leaks in the discharge hose the valve will not close. Or the valve is faulty. With an empty tank, plug the valve and run compressor and test airline for leaks with soapy water. If no leaks, empty tank of air and restart compressor and take note of the amount of time it takes to fill the tanks to shut off. If it takes an unusually long time to fill, then the compressor probably has valve problems causing low air volume. If the compressor fills to shut off in a short time frame as compared to a similar model then replace the valve. Leaking valves in the head will also cause the pump and discharge tube to run very hot. Parts are available at www.toolpartsdirect.com Good luck with your repair.