Hitachi compressor doesn't build pressure above 50 psi.

by Roman
(Milwaukee WI)

Hitachi gas air compressor EC2510E.

Used everyday, built pressure to 80-90 psi.

Replaced unloader valve and adjusted from 110-150 psi. Worked fine for a week or so, then the pressure wouldn't go over 50 psi.

Ordered a new pump but no change at all.

Won't go over 50 psi and keeps running. It is sucking air in at the intake all the time. So it has new unloader valve and new pump, what else is there to build pressure???

No leaks when shut off, thought it might be a faulty gauge but the pressure is really low in air hose.

Can you save this compressor from being junked?

Comments for Hitachi compressor doesn't build pressure above 50 psi.

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Jul 29, 2016
by: Doug in

You can probably put a tee in the line from the pump to check pressure.

You replaced the unloader, did you try to disassemble the original one to see why it failed?

Jul 28, 2016
New unloader again
by: Roman

I finally got tempted and bought another new unloader valve, but no change at all. Still gets to 50 psi and no more. Engine starts on first pull and running strong, belt is tight as well. I blew air through the braided hose, there seemed to be no blockage. New oil in pump and motor. The pump is blowing air where braided hose attaches to it but don't know how much. Is there a way to put a gauge on it to see what pressure is at that point? I don't know what else could be the culprit. I don't want to throw it away now since I put $350 into it. Somebody help, please.

Oct 19, 2015
50 PSI
by: Doug in

Sounds like the unloader went south (again?).

The pump is said to pump some oil, so if you did the pump swap w/o cleaning the unloader. . .

The pump should suck air all the time, just less when at idle.

All that based on you replacing the unloader due to failure.

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