# craftsman 20 gallon will not build pressure.



## joea (Jun 18, 2018)

Model 919.164150. It is clearly a DeVilbiss built unit. Has not been used in a year. Powers on and runs, but does not build pressure at all. I heard air escaping and it appeared to be leaking at the tube (item 17 on parts list) and the Pressure switch unit. I thought it was coming from that brass whatever it is the tube attaches to, that has a thin movable projection out the bottom that gets lifted up a bit when actuating the on/off lever on the switch. 



Not sure of the function of that part, but suspect is is an "unloader". I just tested the tube and that part and can see that it does hold air and the little projection appears to actuate a valve. Not sure how this can build pressure when the switch actuates the unloader like that.



I guess I'm missing something basic.


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## joea (Jun 18, 2018)

joea said:


> Model 919.164150. It is clearly a DeVilbiss built unit. Has not been used in a year. Powers on and runs, but does not build pressure at all. I heard air escaping and it appeared to be leaking at the tube (item 17 on parts list) and the Pressure switch unit. I thought it was coming from that brass whatever it is the tube attaches to, that has a thin movable projection out the bottom that gets lifted up a bit when actuating the on/off lever on the switch.
> 
> 
> 
> ...


So, this was leaking at the "furnas" (unloader) valve. I found these are available, so ordered and installed one. Still leaks at a rapid rate from the vent of the valve. Is there a second secret, or is it most likely I got a bad replacement valve?


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## joea (Jun 18, 2018)

joea said:


> So, this was leaking at the "furnas" (unloader) valve. I found these are available, so ordered and installed one. Still leaks at a rapid rate from the vent of the valve. Is there a second secret, or is it most likely I got a bad replacement valve?


I tested the new valve off the compressor and it does seem to seal. What could be causing it to no seat when on the compressor?


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