i have a 400c that will not pump any pressure above maybe 50psi i can take the leader hose off and its pumping replaced check valve as per girl at hornblasters waste of money any advice:confused:
Are you positive about the check valve? If it builds to 50 PSI, I’d let it build pressure and then check for return flow through the intake hose.
If you’re getting all of that air coming back out of your intake then you’ve still got issues with the check valve.
If the 50 psi is holding steady and it’s just not building any more, check for blockages on your intake, remove your leader from the tank and confirm the unit is pumping high pressure air.
Failing all of that it could be an internal fault with the piston assembly (e.g. blown compression ring, reed valve not sealing, etc.)
Time for a quick lesson in the engineering of a check valve 
The check valve is a spring loaded ball. When the compressor turns on, this compresses the spring and allows the air to flow around the ball. When the compressor turns off, the ball returns to the orifice. If any part of this valve is accidentally crushed (over tightened, wrong tool used to tighten etc.) this will constrict airflow.
The below diagram is a general diagram for different kinds of check valves. The bottom two are similar to the type I am referencing, more so the bottom right. These necessarily aren’t a diagram for a Viair brand valve but gives you a picture for reference to plug in my lesson with.
Typically when the compressor builds a certain amount of pressure and nothing more, it is the check valve. Be sure it isn’t over tightened as this is a common mistake. We typically suggest to hand tighten the valve, then use a wrench 1/8" of a turn and this should be plenty.
With that said, it certainly can be something other than the check valve. As DBO said, if you’re positive it isn’t the check valve, it is most likely an internal problem. You are more than welcome to send pictures to my email at Angie@hornblasters.com of all the internal parts to see if we notice anything. We do have all the replacement parts on hand.
If the compressor is less than a year old, it is also still under the manufacturer warranty and calling Viair may be the best route to go.
If you live where it gets really cold in winter, you may have moisture frozen in a line.
Just an FYI for you guys. Lance left Viair mid July 2012. If anyone needs to email Viair, send an email to Jessy. She filled Lances shoes. customerservice@viaircorp.com
Ok here it is i have the 400c it was working fine then i blew a fuse when i relocated it to my toolbox. After i blew the fuse and ran the new wires everything works fine except it wont release air when i hit the switch. When you turn on the key in the morning it builds pressure and cuts off like it is supposed to. When you hit the button you can hear the relay click but it wont release air. I checked the grounds and there all tight. Do you have any suggestions that might help?
It sounds like a broken solenoid. Just go through a process of elimination. I’d take the wires off the solenoid and connect them directly to the battery terminals to see whether it still opens correctly.
Would it be that even if the pump still kicks on and the relay clicks? But ill try it here in a few thanks.
Welcome to the forum. How long does the compressor run? Do you have a gauge on the tank?
Yes i do it runs until 150 like the pressure swith says its a 110/150
Then I agree with DBO.
Well thanks ill let you know how it turns out
Well i put a new one on and it didnt work still doing the same thing just got dark here in carolina so im gonna repace the switch wire tomorrow i guess
Have you checked and confirmed you have air at the solenoid inlet?
Drain your tank then take the incoming line out of the air solenoid (i.e. the one going from the tank to the solenoid) and hold your thumb or finger over the end - then switch on your compressor. If you have air building at that point then your issue is up-stream of the solenoid.
Next step, I would take the outgoing line off the front of the solenoid (i.e. the one going to the horns) and then try triggering the solenoid. If that works… well you get the drift - just keep working your way up front until you reach the horns.
Make sure you got the right amount of juice going to the solenoid. Try connection straight to the battery terminals to see if you can get it to open.
Ok i really appreciate the help i could rebuild the powerstroke but cant get the horn going thamks ill let you know