I have a hitachi nail gun NR9oGC that will firer 6 to 8 times and then stop. if I take the battier out and put it back in most of the time it works .I got new battie and that help but still not all t

If gun firing but nails not being driven could be one of two basic problems:
1. Nail jammed in magazine not allowing nails to move up.
Empty magazine, does follower move to top of magazine. Push gun against work piece, does fan motor start? Yes - jam in magazine or lock out bar not operating. (this would allow nail un to fire when out of nails)
2. Piston/driver not returning fully after firing, hence driver blade on top of next nail instead of behind it. This could again be caused by a jammed nail or just a nail head. Another case of not returning is the combustion chamber not making a good seal, check O rings on framer (they are steel rings on bradders) it may just need a good clean it is surprising how dirty they can get and if not cleaned a build up of dirt could break a seal. If not been cleaned for a long time worth checking piston rings, worst case scenario dirt builds up around the rings and stick fully in requiring new piston if the rings will not come out.
Nail guns work on the principle that an explosion pushes the piston driver forcing a nail into the work piece, after the explosion a vacuum is created and it is this that 'sucks' the piston/driver back up the cylinder.

If your using refills that have wire holding the nails together.
Check to see if bits of wire, debris is collecting in around the striking hammer. I switched to paper and never looked back. Must have gone through 5k worth of nails and rarely jams. Other things to check,
1. Check the striking hammer, make sure it is not bent or damaged.
2. Check air pressure, Low pressure can cause jamming, misfires.
3. If the tool needs pneumatic oil, 2-3 drops before you start good rule of thumb.
4. Check spring return. Sufficient pressure must be maintained or the nails will not feed properly. Misfires, incorrect feed, jamming etc.
I had a Hitachi brad nailer and it was horrible. Fire 1 brad nail would jam or misfire. Did everything I could think of nothing worked. Put it up, got a Rigid brad nailer and never looked at the Hitachi again. :)
Sometimes you just get a lemon! (PS I understand you have a framing nail gun. Brad nail gun above is used for an example)
Hope this helps

I presume the gun fires but no nail is ejected. A possibility is jammed nails in the magazine. Do you see a mark in your work piece of the driver blade? If yes then it is most likely jammed nails. If not could be a broken driver blade. If gun does not fire could be gas problem. (check in date, yes it does have a use by date), another cause of not firing is a broken wire particularly around trigger switch (switch is on trigger and hence the wires are flexing every time trigger is pressed). Another cause of not firing is a brass spring clip in handle assy if this breaks it stops the gun firing. Recently I have had more broken wires than anything else on these guns. Worth noting is that the Stanley Bostitch nail guns suffer the very same faults. Also note they are the same gun just different colours so you can fit Hitachi parts to the Bostitch and they are cheaper.

Are you oiling your nail gun, it sounds like it's suffering from a lack of lubrication? It doesn't take much pneumatic tool oil but nail guns have to have it to work for any length of time. If you have been oiling the gun, you may have o-rings inside the gun that are worn, broken, or blown out of place. You can remove the head and check the condition of the o-rings and see if the inside of the gun is dirty. Clean the gun up and pay partucular attention to the o-rings on the bottom half of the cylinder and piston. When reassembling the gun be sure to grease the o-rings well. If you still have the same problem you may have to rebuild the gun by replaceing all the o-rings. Unfortunately Hitachi does not make rebuild kits so you have to go to their website on an aftermarket site like www.ereplacementparts.com and order each and every o-ring.

The condition of the driver oring is an indication of wear of all the other orings in the gun. Remove the nails and lightly tap the nose against piece of wood. If the driver drops to bottom of cylinder the oring is worn out and time for oring kit. Hitachi nailers are sensitive and will double fire if placing the foot against work then depressing trigger. Adjust the depth thumb screw several turns either direction then depress trigger and quickly bump gun against work. Good luck with your repair.

Most nail gun manufacturers make an assembly grease but a light grease like lithium will work, it's just to lube the rings during assembly. Most of it will get washed away by the gun oil you put in the gun each time you use it.

Most likely only needs lubrication. Remove head and apply silicone paste lube (sold at lowes in the plumbing department) to orings of the headvalve. Pull piston and lube oring. Should be ready to work. Good holiday

Orings, they have to be replaced every few years. Warranty does not cover them.

Any Hitachi service centre should stock them. Or find your model on Ebay:

http://shop.ebay.com/i.html?_nkw=hitachi+o-ring+kit&LH_IncludeSIF=1&_arm=1&_armi=0&_armm=20&_ruu=http://shop.ebay.com/i.html%3F_nkw%3Dhitachi%2Bo-ring%2Bkit%26_arr%3D1&_rdc=1

Hope this helps!

Thanks

1.Remove the air hose
2.Hold the nose down on a 2x4 on the ground. Make sure the safety guide is full depressed.
3.Squeeze the trigger.

(I realize that sounds redundant, but I have to insure your safety as much as possible. We at FixYa want you to be safe. A Framer Nailer can be dangerous if safety precautions aren't observed)

4.Pull the slide back, and grab around it with your hand, up against the back of the gun. (Magazine)
If you accidentally bump the latch lever, the slide won't spring forward, possibly causing you injury by using this method.

5.Remove any nails. Pull the plastic strip of nails out.

6.The method I use here is to rest the air chamber cover on a table. (Top of the gun) Nose AWAY from your face. I use a small flat tip screwdriver, and see if I can move the Driver back up into the gun. Then see if I can ease one nail out at a time, by moving the nail down out of the nose.

You have two nails trying to drive out at the same time. They need to be separated from each other, so that you can get one nail out at a time.

Most of the time this occurs because of lack of lube. The gun is supposed to have 4 to 5 drops of pneumatic oil, added to the air hose inlet before starting the day out.

(Gun is faced so that the air inlet connection is straight up, oil is added, while the trigger is being squeezed in at the same time)

I don't rely on oilers in the air line. I think they're a bunch of hooey. I've had very few problems, when I have added oil manually at the start of the day.

Sometimes using those 'bargain' nails will cause a problem also. If you find a brand of nails that are cheap, this is the usual result.

Sometimes we framers are too fast on the trigger, and do not have the safety guide fully depressed, before firing the next 'shot'.

If you have further questions please post them.

I think you'll have to look at your specs on your nail guns and see what the demand is . Whether measured in cfpm or psi, your compressor will tell you the max output of each of those. Then you divide the maximum sustained output of the compressor,, lets say it is 60 psi. Let's say the guns require 10 psi, 60 divided by 10 is 6 = 6 nail guns. This is completely hypothetical as I have no idea what your nail guns require, only you know what kind of guns you have.If you need to run more guns than the compressor can push air for, you'll have to invest in another compressor, maybe even one larger to handle the guns running wide open consistent nailing. Nothing a drywaller hates more is than for all the cursed clip nails not being drove in all the way, lol, and that's what will happen with insufficient air supply.
Matt