check all the lines and the Drain valve for leaks. I can think of only a few things: a leak OR the pressuretrol is bad. I would hunt for leaks as I first suggested. If you have an air hose attached disconnect it, run the compressor and see it problem goes away. If nothing changes then problem is in the compressor itself. If this is an older unit may also be a hole in the air tank itself from internal rust. If that turns out to be the problem STOP USING IT IMMEDIATELY scrap it.:yes:
There are a number of possibilities. Usually, the oil-lubricated pumps don't fail, it's usually something else.
While it's running, feel around (careful, some parts are pretty warm!), and possibly you can find the leak. Concentrate on the piping from the pump to the tank. Make sure the unloader valve is closed. Feel around the pump cylinder for a blown gasket.
The intake filter could be clogged as well.
Once it builds up any pressure, does it hold it after it's turned off? If so, the problem isn't with the tank, it's either the pump or piping.
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