Compressor doesn't build pressure - motor stops - then starts with intake plugged?

by Steve
(England)

My cheap chinese air compressor had this problem from new. For various reasons, I've still got the thing.

It's a 2.5 HP NuAir compressor - single cylinder pump.

It runs OK until the tank pressure is 3 bar (45 psi) or so, then the motor can't move the cylinder anymore - it is still trying to (as in it still has power - the motor hasn't been switched off!), but try as it might, it can't turn anymore.

The one diagnostic I have tried, that might help: When the motor stopped moving, I sealed the air intake with my finger - it immediately started pumping again (but of course, didn't build any more pressure).

Does this make sense to anyone? Thanks in advance for any repiles!

Steve

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Bill says...

Sorry Steve. This is a weird one for me.

Anyone else have any ideas for Steve?

Bill