Coleman VP0200406 compressor The tank air pressure will not go above 40 PSI. changed the two air lines (copper and nylon) No air leaking from them now. what could be problem > need new gauge?

The pressure hose is not leaking on the connections between tank and cilinder the pressure unloader underside on the pressure switch with little blue or black little hose is closed (not blowing air out ) if the compressor is running? and is the check valve on the tank not dirty inside ?? if the pressure unloader or connections are definitely not leaking.
A little piece shard of the membrane plate(s) thats insite the head of the pressure cilinder is broken and is inserted in the black rubber of the check valve .
More possibilitys the pressure switch itself. the insite diaphragm membran has a problem replace always the whole pressure switch if its defekt.

Hi mjschulte815

Here are a few things to check, you may have already checked some of these.

Electricity...Compressors will run best with full 115Vot 15AMP/Or 220V electrical supply from a circuit, over the shortest electrical cord as possible.

Air Leaks..Place your ear close to the compressor and listen for air leaking, if you hear air that is not normal and means you have to locate and repair whatever it is that is leaking.
Check the air unloader valve... The air unloader valve will blown out air when you turned off the compressor, that is normal.
But it should not have air leaking out of it all of the time. If so then it is faulty and in need of repair/replacement.

Valves...If either the intake or exaust valves fail, breaks, or fails to seat, then your compressor will run 24 hours a day and never build up to the correct pressure for shut-off.

Gaskets...Check to see if your gaskets have failed.
You could have a gasket failure between the pistons and you will never know it because it shows no external air leak.
If this situation happens then the air will only cycle between cylinders and never build up the correct air pressure.
One way to check the gasket is remove the air filter, then put your hand over the intake.
Please take time to rate me
Bud
If correct then it will **** you hand against the intake.
If the valve or valves have failed then you will feel the air sucking in and blowing out.

Piston Rings and Cylinder...The piston rings could be stuck,broken, or worn and not allowing the correct pressure to build up in your tank.
A worn cylinder will also contribute to the problem of pressure build-up.

Pressure Switch...Check for air leaks at the pressure switch, it has a rubber diaphram that can fail and leak air out of the system.
Please take time to rate me
Bud

Pressure relief valve is sticking. Shoot it with some PB Blaster.

Sounds like you have a tank check valve leaking. It is located in top of the tank. The copper discharge line from the compressor goes into the check valve. Make sure there is no air pressure in the tank. Then Remove the large copper discharge line. Also remove the small copper line from the side of the check valve. Once the lines are removed you can remove the check valve. Most of the time the check valve needs replacing. Sometimes they have large pieces of trash holding them open.

You have a receiver tank check valve leaking. If you loosen the 1/4 tube slightly and air blows out more and will not stop replace the tank check valve. If you follow the copper line for the compressor HP head back to the tank you will see that the line screws into the check valveand the check valve screws into the tank. Bleed all air from the tank,remove the 1/4 line and the 3/4 line from the check valve. Then unscrew the check valve. Install a new check valve and connect the lines. Problem solved.

make sure the bleeder unload the pressure when the compressor stops.if not it will be too hard for the motor to start ,it will drive too much amps and trip the breaker.just after its stops you can also unscrew the air line to see if it still under pressure(it will be a 1/4 nylon or copper line)if the air is comming out STEADY from this line replace you check valve.hope this will help.

not sure but it sounds like the piston ring is worn out or you might have a bad valve.
p.s. its not your typical valve like in a car.

is it a wet compressor, check the oil.

your in take valve is not closing alowing air back to the piston. its mownted on the tank. the line from the pump to tank at tanks end. replace it frist

with it running check regulator knob .it pulls up turn right pressure should go up.if not regulator bad

Usually, a leak at the pressure switch unloader valve is caused by the checkvalve in the tank. The unloader valve at the pressure switch bleeds out the air from discharge tube after compressor reaches set pressure. This only takes a few seconds. If air continues to leak then air is leaking back into the discharge tube past the tank checkvalve. Follow the air discharge line from the compressor to the brass valve at the tank. The brass valve is the checkvalve that holds the pressure in the tank. There are usually two connections at this valve. One is the unloader tube to the pressure switch. Simple test for leaking checkvalve, with pressure in tank unplug or switch off the compressor and remove the small unloader line at the checkvalve(brass valve) and look/listen for leak. If leaking, remove the checkvalve and examine seat/check for debris keeping the valve slightly open. If it cannot be cleaned, order generic replacement from www.grainger.com. It will cost less than the factory checkvalve. Just pay attention to the thread sizes for easy fit. Good Luck on your repair and email if you have questions.