Use of Hitachi EC510 air compressor

check and test cut out may be faulty or failing

i suspect that the start/run capacitor is faulty or the centrifugal switch in the back of the motor is faulty

have an accredited electrician check the motor , capacitor and the pressure control switch
the air leak at the head is a faulty non return valve in the compressor line to the tank
available at good tool shops for around $60.00

When the pressure reducer fails, it may leak around the adjuster or it may close as yours has. A temporary fix would be to remove the safety unloader or a tank pressure gauge and install a tee fitting replacing safey or gauge and install a quick fitting for air. You will only have tank pressure available however this is a temp fix untill you replace the pressure reducer. You do not have to replace with factory parts, there are generic parts available at Lowes or similar stores. For factory parts go to www.toolpartsdirect.com. Good luck with your repair and post again if you have other question.

yes pressure release valve bad!

replace the pressure vale or try lubing it for wd-40 first otherwise the shaft has worn inside and is sticking.

This is a stab in the dark.....but have you emptied the condensation out of the tank? It may reach max pressure....but have little air compressed inside the tanks. Just a guess.

how do you know one tank drops to zero unless you have a pressure gauge on both tanks sounds unlikely unless you are looking at the gauge on the pressure regulator

You did not state whether the compressor would kick on automatically, or whether it would kick off at some point, so I have to work through it with you....
If the compressor runs, you should see pressure on one of the two gauges. The gauge that is closest to the tank is the pressure that the compressor proper is putting out to the tank, and is the primary gauge. The other gauge is the pressure supplied to the tool via the hose, downstream of the regulator. If you are seeing pressure at the first gauge, that's a good sign. Also a good sign is if the commpressor runs and switches off at some point before lifting the PRD (pressure relief device). This tells you that the compressor is pumping and that the pressure switch is working. If this is the case, try working the regulator control knob and watch the second gauge. The regulators can be tricky; sometimes the regulator knob operates in the opposite direction than expected, depending on the type of regulator, so experiment a bit. (Usually there is wording and an arrow on the knob telling you the direction to adjust. If you start to see a rise in the pressure on the gauge, go ahead and set the desired tool supply pressure.
If you can get a pressure on the first gauge, but nothing on the second gauge no matter how you manipulated the regulator, you should suspect a bad regulator.
If there is no pressure on the first gauge, try cracking open the drain valve on the tank and starting the compressor. If you get air out of the tank with no indication on the gauge, you should suspect a bad primary gauge. If you get no air out of the tank, open the drain valve further and check again. If still no air, the compressor itself is suspect. You will need to determine that the motor is in fact turning the compressor. If the motor is running, but the compressor isn't moving, unplug the compressor and reconnect the linkage. If the compressor will run with the motor, the compressor may be shot, or tha air intake may be plugged off. Remove the cover on the air intake and inspect the filter. Clean and replace as required.
If the compressor will start when you operate the on/off switch, but does not kick off at some point, the pressure switch is probably at fault. It is an odd piece of work....it is mechanical, electrical and pneumatic, all at once. You would need to troubleshoot each portion in order to put it right. The most common problem with the pressure switch is burned or welded contacts, followed by wiring issues to the contacts, then the air line to the switch, then mechanical linkages within the switch.
This humble guide should be enough to get you going. I hope that it has been useful.

Regards, and good luck!

--W/D--

The regulator sounds like it is cranked closed. Try slowly operating the adjusting knob in the opposite direction. As the valve moves, you should see the pressure rise on your gauge (it probably does work).
Hope this helps....now go make something!
Best regards, --W/D--

About the best that you could do is compromise between using one cord and more hose. Your compressor draws about 15amps and will probably draw more as the units heats up. One 12 gauge 100' cord will most likely give you enough power to run the compressor (do not use 14 or 16 gauge). (depends on strength of outlet) There is a voltage drop of about 7.5 volts on 100 feet but should deliver 15 - 20 amps. Best to test with meter as compressor runs to prevent damage to capacitors. Now for the hose, that leaves about 250 feet to reach project. Pressure drops in the hose depending on inside diameter up to 40 psi per length. If you used a 1/2id x100 hose at the compressor then the rest 3/8 id or maybe 1/4 you may have enough to power your gun. Another consideration to get more pressure is to use maybe 100' or more threaded pvc pipe or metal pipe 3/4 or 1"id. Finally to get plenty of volume at the gun, you could use a small air tank (3-4 gal) at the end of the run then another jumper hose from the small tank to the gun. Unusual circumstances/challenge makes for unusual solutions. Good Luck on your project.