I have a hitachi nr90ae that will not fire. Depress nose and trigger and gets nothing. What's next?

Easy to check. Remove nails from gun and connect to air supply. Using hard rubber pad or soft wood depress and hold trigger and push nailer safety against pad and hold there. The gun will fire but the driver will stay down until you pull back on the gun and relieve pressure on the safety foot. With driver down examine the tip of the driver. It should look square and should extend about 1/4 inch or more past the nose. If tip is broken replace driver. If lots of air is leaking past the nose during test, also replace the lower bumper. Good luck

If no air is leaking from the gun, take out the nails, remove trigger by removing 3mm hex head bolt to expose the trigger pin. With air connected and side door open so that you can see the feeder, quickly depress the trigger pin with finger. Gun should fire. If gun does not fire (only makes air sound at trigger) dissconnect airline, remove head and lube headvalve with white grease and reinstall. Test again. If ok replace trigger. If still no joy, replace trigger valve with new factory or generic (part # TVA6). If gun fires but does not activate the feeder claw, remove two 6mm hex bolts from front of gun and split apart upper and lower body and check white oring (part # 149885) Good luck

use the lube that came with the kit, you can replace everything correctly but if oring gets pinched it will still leak

New user will jam the gun/ nails because gun was most likely not bump fired. Placing the gun then depressing trigger will usually cause double fire in the hands of new user. New user should practice on scrap lumber bump firing at many angles till they get the idea; or give them a training period with a nailer that has a single shot trigger (they may develop bad habits with single shot however).

Over time the orings within the nailer will dry out causing problems. Adding oil thru the air inlet will not get oil to all the orings. If the gun had been in storage, add a few drops of oil into air inlet and spray silicone (or teflon) spray lube into air discharge opening at the top of the gun (it is difficult for oil to get into the head from air inlet). Before you connect the air, remove the nails and make sure that the drive piston is at top of cylinder. You can verify by inserting long metal tool (slightly larger in diameter than nail shaft) into nose of the gun and tapping firmly. This will move the piston up against the headvalve and hopefully reset it and allow oil the lube orings. If the headvalve is stuck, gun will not fire. Make sure that the safety foot is depressing the firing pin at trigger valve all the way in. Retest gun for proper action. If still no joy, remove the head and lube orings with silicone paste lube(silicone past has better sealing action but dries out over time). Good luck

May be due to broken tip. Easy to check. Remove nails and leave door open. With door open, lightly tap the nose of the gun against coiled rubber hose or soft wood. The driver should stay at top position. If driver falls to bottom of the cylinder, replace piston oring. Now press nose of the gun against old coiled up air hose or soft wood and squeeze and hold trigger. The gun will fire and the driver should stay in the down position untill you release the trigger (if not single fire trigger, if single fire trigger remove trigger and press the trigger pin with finger). While the driver is down, make sure that the tip extends past the nose about 1/4 inch (if air leaks past the nose in this position, replace lower bumper). If the driver does not extend past the nose, replace driver. Good luck

Worn orings in gun and the trigger valve can/will cause problems as you describe. Remove the nails and leave open the latch. Lighty tap the nose of the gun against coiled rubber hose. The driver/piston should stay in the top position (if the driver is down or comes down after test, replace driver oring). Now push the nose against the rubber hose and activate/hold trigger, while holding the trigger/gun in this position, the driver will /should stay down under pressure. At this point no air should leak out of the nose of the gun. If air leaks out of the nose, examine the lower bumper for cracks ( replace as needed ). Finally remove the trigger and examine the firing valve pin. If it has a plastic pin, looks worn and wobbles from side to side, most likely needs to be replaced. If however it has a metal pin and it seems to fit snugly, do not change unless it is leaking air. Good luck

Remove the nails and air supply. With side door open notice position of driver. Driver should be at top position with tip not visible. If driver is down and it moves within cylinder when you tilt nose up then down again, time to replace orings. If driver is down, it should extend past the nose about 1/4 inch (if driver is broken at the tip the end will look rough and nail will not drive in all the way). If driver extends past the nose more than 1/4 inch then lower bumper may be breaking up /cracked. Easy test for proper function. With nails removed and side door open, connect air to gun and dry fire gun against hard rubber or old coiled air-hose (with air connected and trigger depressed, no air should leak from trigger area, if air leaks when trigger is depressed, look for fault at trigger pin). Feeder should move back then forward in quick motion almost matching speed of driver and driver should not creep down between shots. No air should leak from nose of the gun (push nose against hard rubber and depress trigger and hold in this position, driver should stay down with very little or no air leaking out of nose, when you release trigger, driver will return). If air leaks out of nose while holding in this position, replace lower bumper. If a quantity of air leaks from valve in front of trigger, cylinder orings may need replacing or outer part of cylinder has fine scratches (remove scratches with 400 grit paper). Parts are available at www.toolpartsdirect.com. Good lucki

Remove nails and remove trigger to expose trigger valve pin. Place nose of gun against rubber pad or old coiled up air hose to absorb impact of driver and with very quick and deliberate motion press in trigger pin. If gun fires, then problem is with safety foot not pushing trigger pin all the way in (or worn trigger). Make adjustment as needed or replace faulty parts. If gun still does not fire, then likely problem is with headvalve. If headvalve orings are leaking, gun will not fire. Test for leaking orings as follows. Remove head and remove headvalve, apply silicone paste lube (plenty) to all orings and where orings contact. Assemble and do test above. If gun fires then surface where orings contact is allowing air to leak(smooth with very fine sandpaper if scratched).

Where does the air leak out from? If it leaks from the trigger DeWalt makes a trigger valve assembly part # 641006-00 list 8.89 BUT if it leaks from other areas we have to look into it deeper. If it is just the trigger valve let me know and I will give you instructions how to remove and install the new one.