It seems to not have enough pressure from the pump to pressurize the tank.

I took line off from pump to tank and put my finger over it and pretty much stopped the flow.

Are rings bad in pump and is shot or something else?
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Howdy anonymous person…

Be good to know the make and model, as your air compressor problem may be common to one of those.

Your check of pulling the line off to the tank and seeing how much pressure is being generated is a good one. You have now pretty much isolated the compressor lack of pressure as being upstream of that point.

I would pull the intake filter too, and do the same check. Is it pulling air in strongly, or is it huffing air back out too? If huffing, that’s a sign that the intake valve is pooched.

If it is pulling air in, and air is not being pumped out, yup, it could be a sign of cylinder piston ring wear, but then, you would be getting a lot of air out of the oil fill cap which is vented.

If that isn’t happening, and you are getting strong suction at the intake, my money would be on an internal pump gasket blown which is allowing air to flow around inside the pump from high pressure to low, but not down into the tank.

When you open up the pump, you might as well have a new valve plate and gasket kit, as both are, in time, wear items inside the pump.


Compressor won’t build pressure?

by ted van zutphen
(ottawa, canada)

my compressor operates fine but it won’t build any pressure while its running,i have no idea whats wrong,need help,thanks
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Ted, it is always useful to know the make and model of an air compressor when trying to troubleshoot a compressor problem.

And, if your compressor is running, and it is not building pressure, then it sure is not “running fine”. 🙂

The first thing I would do is to remove the intake filter. That eliminates that part as being the source of the problem, and at the same time, allows you to feel, while the compressor is running, if air is being pulled into the intake port.

Is it? Please post a comment here with what you found.


Air compressor will only pump up to 30 lbs.of pressure?

by Tom
(Ms)

Why my air compressor will only pump up to 30 lbs.of pressure?

when the pressure reaches 30 lbs. that is all it will compress.

air begins to come out the small vent holes on the oil fill plug

also at the intake air filter. Could this be reed valve

problems?
Thanks
Tom F
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Tom, I’m guessing that when your air compressor tank pressure reaches 30 PSI, the air compressor keeps running, but no more pressure builds?

That being the case, have a look at the troubleshooting section, the page about why air compressors run but don’t build pressure. Some things there to check.

Offhand though, if you have air coming out the oil fill tube cap, and air coming out the intake, you’re likely looking at a new piston seal kit, a new valve kit and a new gasket kit.