MY TANK DOESN'T FILL ALL THE WAY UP

If your air compressor is running but your tank isn't building pressure like it should, or it stops filling at a certain PSI and won't go any higher, there are a few things that could be causing the problem. The good news is that most of these issues are easy to diagnose and fix. This guide will walk you through checking for leaks, testing your valves, and diagnosing compressor problems to get your system back to full pressure.

The most common reason a tank won't fill is a leak somewhere in your air system. Even a small leak can prevent your tank from building pressure past a certain point. You might notice your compressor fills to 40 or 50 PSI and then stops climbing, or it runs constantly trying to keep up with the air escaping.

To find leaks, spray down your entire system with soapy water or Windex while the tank has some pressure in it. Any leak will cause the mixture to bubble up, even if the leak is very small. Check these spots carefully:

• All fittings on the tank and air lines
• Your solenoid valve connections on both the inlet and outlet sides
• The drain cock at the bottom of your tank
• Your safety blow-off valve
• Any quick-connect fittings or push-to-connect fittings

If you just installed your kit, double-check that your solenoid valve isn't installed backwards. A backwards valve will let air pass through constantly and typically allows the tank to fill to around 40 PSI before it stops. The valve should have an arrow indicating flow direction - make sure air flows from your tank through the valve to your horns, not the other way around.

If you've sealed up any leaks and your tank still won't fill, your solenoid valve might be stuck open or malfunctioning. Here's how to test it:

Remove an air line or fitting from the outlet side of your valve. With the tank pressurized and the valve switch off, check if air is flowing through. A properly working valve should be completely sealed when it's not activated.

If air is passing through constantly, disconnect one of the two wires from the valve. If the leak stops when you disconnect the wire, you have a wiring issue causing the valve to stay energized. Check your wiring connections and make sure you don't have any shorts.

If the valve continues to leak air even with the wires disconnected, the valve has failed internally and needs to be replaced. Valves can fail over time, especially if they've been exposed to moisture or excessive heat.

If you've confirmed there are no leaks and your valve is working properly, but the tank still won't build full pressure, your compressor may have an internal issue.

Let your compressor run until it reaches the highest pressure it can achieve. Once it stops building pressure, remove the air filter from the compressor head. If you see a steady stream of air blowing back out of the filter housing, your compressor has a bad internal seal and can't build higher pressure. This usually means the compressor needs a rebuild kit or replacement.

If your tank won't build ANY pressure at all, disconnect the compressor from the tank by unthreading the leader hose. Hold your thumb firmly over the end of the leader hose and turn the compressor on. A healthy compressor should have enough pressure to knock your thumb off the hose end. If it can't, the compressor has failed internally and needs repair or replacement.