Compressor slows to a turtle speed as pressure grows

by Russ Rodrigues
(SF, Ca USA)

when starting my 1998 5 hp verticle compressor starting #909 and ending in 221 starts building pressure then around 40psi the motor will slow to a crawl and stop., usually blowing the 15 amp breaker.,at the box.

And when I reset the breaker to start again the motor will be verrry slow then thats it.

I've gotten a new check valve and it is in better shape than the one I replaced, and at least this one hisses when I shut it down. I believe I have multiple buddy bugs here., more than one prob.

The pump works smoothly and doesn't seem too bad however the motors under load craps out.,air is pumping into the tank which is 20 or more gallon one, but doesn't reach limit enough to shut down on its own.,like it used to.

my start cap measures OL on measuring with ohmmeter and on dc voltage setting doesn't measure down w/meter power.

Could this mean my cap start is bad? I ran it w/out the start cap briefly just with the run and it ran slowly by itself but the motor will not run w/out the start cap .

What could I be looking at with this prob. ,I don't want to keep throwing money at this thing . new caps or caps ,bad motor windings ,centrifugal switch, pressure switch, unloader valve or even the pump on this oil less compressor. Need lot a attention pls.

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May 17, 2016
by: Doug in

You got a model on this? Also for the motor.

Sounds to me like your start cap is OK, but the run cap is probably bad. Possibly both, but dunno w/o motor info.

May 16, 2016
narrowed my prob
by: russ

Before I posted my compressor issues above however I think I've narrowed the prob out of the motor. I had removed the pump and the motor ran endless better than before . so therefore I suspect the airless pump piston rings worn no compression., Ive gone ahead and ordered a replacement to see if that helps. ,the piston and sleeve assy. ,

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