The tank fills with air, but the motor doesn't shut off. It continues to run.

After flushing the toilet, water still fills the tank till then the shuts off valve reaches a certain level. When the shuts off valve reach the level it disconnect the water connection to the tank and the filling process of the tank shuts off.

So, if your fill valve didn't shut off then maybe there's a problem with the shuts off valve, open the fill valve and fix it. If you can't fix it call a plumber for it.

This problem is caused by either the starter capacitor or the in-tank check valve. Ez to check. With no air in tank, start compressor; if motor hums or has difficulty suspect capacitor. If motor starts, partially fill tank and unplug the power. Check for air leaking at the pressure switch or air coming out of the air inlet (remove the air filter). If air leaking, replace check valve. If no air leaking, again let out all the from the tank and connect power. Allow the compressor to fill and shut-off. After the compressor fills, again listen for air leaking from the pressure switch unloader valve. If air continues to leak from unloader, replace the check valve. Good luck

You didn't state your model number so I won't be able to tell you what specific parts you may need. If your guages are correct and the tank is coming up to pressure as it should but the motor doesn't shut off when the peak pressure is reached, you have a bad pressure regulator. They're easy to replace. If it's possible your guages are off and the shut-off pressure isn't being reached, the motor will continue to run as long as it has power. Reasons for not reaching peak pressure in the tank could be a leak somewhere like the pump to tank line or drain valve, a bad valve plate that isn't sealing properly or damaged piston or cylinder assembly.

If air leaks when motor is off, fault most likely in-tank check valve. Follow discharge air line from pump to tank. Brass/steel valve at tank is the check valve. Remove hose to valve and check for leak. Replace as needed. If air is leaking while motor is running fault could be reed valves in head. Faulty reed valves in head, or torn head gaskets will cause very hot discharge air and tank will most likely never fill to shut off (or take a very long time to fill)

Solved this problem. It required a new motor starter (or at least one component from the starter. The main power lead running to the thermal overload relay had oxidized and was conducting current poorly. Each time it would run ( I did this with the motor starter cover off) the lead going to the bottom side of the thermal overload would spark then glow red during the tank fill. I removed the bad section of wire, and installed a new thermal overload in the starter.

strip the cyclinder off and inspect the valves if closing and opening also check to make sure you dont have a blown head gasket also on the tank from the pipe from the pump unit is a gold valve you need to open the end off this valve with the tank drained and turn the ruber around with the spring inside and replace this if still doesnt work get back to me bud

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.

sounds like you need a new check valve which should be somewhere between the compressor outlet piping,tubing,etc and the tank which prevents the air in tank to back feed to the compressor which would cause hard starting and could damage the motor easy way to check is when you shut off the compressor with some air in the tank if the check valve is bad it would continue to bleed air out out the unloader valve .the unloader valve on your unit is most likely part of the pressure switch when the unit shuts of it should only bleed down the pressure in the pump so it would make it easy to start when needed hope i didn't confuse you

sounds like a bad or broken valves in the head. crankcase needs a vent which is sometimes a small hole drilled into the oil fill plug and will normally blow some air out the vent while it runs

PLEASE CHECK THE CAPACTORS ON THE MTR, THE MTR WILL BE HARDER TO START AFTER IT HAS AIR IN THE TANK