Bostitch air compressor CAP60P-OF will not build pressure past 50 PSI

I have done a lot of reading on this compressor; seems like a nightmare unit for the most part. Since I already own it, I might as well fix the darn thing.

This started with the valves in the head breaking, so I rebuilt the head with new gaskets, sleeve, ring and valves. Then the regulator developed a leak; replaced it. Now it runs and runs and won’t build past 50 PSI.

I suspect an issue with the pressure switch. When I disconnect the small black tube from the check valve I get good pressure shooting out; as expected. When I close close off the outlet to the pressure switch it starts building pressure again.

Bostitch exploded diagram of CAP 60 compressor — Exploded diagram of Bostitch CAP 60 compressor

Obviously it is dangerous to run without the pressure switch, so that is not an option. I am baffled by what is happening though; I thought the pressure switch only served as an upper limit shut-off?

Where do I go from here? Any suggestions?

Thanks.
Derek, from Des Moines Iowa

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Sorry you’re having so much problem with your Bostitch air compressor Derek.

Try this. Empty the tank with the compressor off then remove, clean and replace the tank check valve.

Reassemble and test. Any change?

Please let us know as a comment here and maybe upload a photo or two of your Bostitch?

Thanks, Bill

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Same compressor, same problem, I also thought it was a leak in the pressure switch because I thought I heard air escaping there. while cleaning it the switch the little V shaped spring fell out and i can’t figure out how to reassemble. Can you help me out?, says Charlie Webber.

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Charlie, I’m afraid those things are nearly impossible to re-assemble with out having or making tools to do it. They’re pretty cheap, so just replace it.
Regarding the escaping air, they are supposed to do that, but the check valve is supposed to stop the “leak” almost immediately.
You may find this page helpful:
https://about-air-compressors.com/buying-a-compressor-pressure-switch/

Good luck. Doug from s.d.ca

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There are pages on this site about how to reassembled a pressure switch. Here’s one: https://about-air-compressors.com/putting-a-pressure-switch-back-together/ and another is here: https://about-air-compressors.com/put-my-pressure-switch-back-together-again/ . But… as Doug says, the process is hardly worth the aggravation as off-brand, on line, pressure switch pricing is fairly cheap, Bill.