Air compressor runs and pumps but no pressure?

Air compressor runs and pumps but no pressure?


It seems to not have enough pressure from the pump to pressureize the tank took line off from pump to tank and put my finger over it and ptetty much stopped the flow are rings bad in pump and is shot or sometning else
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Howdy...

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.

Cheers,

Bill

Comments for Air compressor runs and pumps but no pressure?

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Mar 02, 2013
Compressor turn, pumps air, but no pressure
by: Anonymous

I have a Briggs and Stratton "Brute" 125psi, 2.5hp, 15gal tank air compressor. When I turn on the compressor, the pressure guages show no pressure increase at all and the tank never fills up. I can feel a lot of air shooting out of the oil breather cap. The air intake sucks in air (i covered the hole with my hand it got sucked in and the tank noise muffled.) I removed, one at a time, both lines to the check valve. The pipe that runs to the check valve from the pump blows a stong amount of air. I hooked it back up to the check valve and removed the outlet pipe that runs to the pressue switch. There was a stong, pinpointed amount of air coming out of the check valve. I tightened everything back up and turned on the compressor and still no movement on the pressure guage. But, this time the oil breather cap releases only a small amount of air. One thing, whenever I turn off the compressor, I can feel air releasing from soumewhere in and around or under the pressure switch.
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To continue discussing this, please start a new thread.

Air blowing out of the oil fill vent cap suggests that you have weak or leaking seals around the piston, and instead of air blowing into the tank, it blows past the seals, into the sump, and out the oil fill vent.

Air blowing out and around the pressure switch is a symptom of a leaking tank check valve.

B.

Feb 04, 2013
only getting 20 psi
by: john

I just replace my pump (bendix air compressor) becsause it was intermittenly locking up. With the new one one I am only getting 20 psi. the only thing i did was change the air pump. since the new one mounts the regulator on the side and not the original (rear location) i had to switch the two lines but they both mount to the regulator. could this be my problem or do i need to some how swap the lines back.
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John, start a new thread please, and add some photos of your new pump and the plumbing so I can see it.

I'm not sure what the problem is but will try to help.

Bill

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How long to fill a 80 gallon tank?

by Tom
(Winnsboro SC )

Gilbarco air compressor (photo: www.machineco.com)

Gilbarco air compressor (photo: www.machineco.com)

How long should a 80 gallon tank compressor take to fully charge

I have an old Gilbarco compressor with an 80 gallon tank and a 12hp motor.

It runs beautifully and charges but seems not to hold a charge. I can cut the air supply off just outside of the tank and it will hold pressure indefinitely.

My question is how can I determine if the pump is recharging at a rate that if sufficient to keep up with demand?

If it is I need to look for a leak somewhere in the supply lines from the tank. It currently takes the pump approximately 15 minutes to charge a tank from 0 to 175 lbs.
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Tom, I have no personal experience with a venerable old Gilbarco air compressor such as yours likely is.

Yet, I think that a 12 HP motor running a pump to fill an 80 gallon tank should take what - 5-8 minutes at most? Anyone with actual stats for fill time for Tom?

While the lengthy fill time may be attributable to a leak, I suspect it more likely is a valve, gasket or seal problem inside the pump.

As to "my question is how can I determine if the pump is recharging at a rate that if sufficient to keep up with demand?" a 12HP motor should allow that compressor to deliver about 48 CFM of compressed air at 90 PSI into the tank. If your air tools are using more than this, pressure in the tank will decay as long as you are using more air than the compressor can generate, whether it is running perfectly or has some seal or valve issues.

I have no idea where you could find parts for this compressor should you need them. I hope someone with a Gilbarco air compressor can comment here for us both.

Cheers,

Bill


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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.

Cheers,

Bill

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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.

Bill

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