Anyone know nail gun repair?

Im getting frustrated trying to figure out a campbell hausfeld finishing nailer that refuses to work, and given grm'ers seem to know every about everything I'm hoping someone can point me in the right direction.

The gun has done next to no work (id say less than 50 brads), now it's refusing to fire.

If you press and hold the trigger its like it's fully automatic, but the pusher is short stroking.

The compressor is running about 8bar and the gun previously worked at that pressure.

There are no obvious air leaks, at least none i can hear or feel.

Internally, the cylinder is in good order, as are the pusher and piston. The head Spring is intact and all orings seem to be ok. I re-lubed everything and reassembled it. No change.

I've pulled down, cleaned and lubed the trigger valve, again, no obvious faults and no change to the problem.

Its doing my head in, because there is obviously something I'm missing, and for a gun wth so little use, it shouldn't be giving me this level of greif.

Many of them have a bypass chamber to allow the plunger to return. If they get a crack or leak in them, it might cause what you are describing. Head gasket leak could also be an issue.

Back when it was working properly, what happened if you held the trigger? Does the plunger stay down and then return when you take your finger off? Or does the plunger cycle back on its own regardless of trigger position? If its the first way, you have an air-return style. When you release the trigger, it fills the return chamber with a little pressure to raise the piston. If its the second, you have a spring-return piston.

Try dumping in a few tablespoons of oil and see if it makes it a little better temporarily. That would indicate an internal leak in an air-return gun.

If its a spring-return, I think its a problem with the safety linkage. If it is stuck half open, it could cause the symptoms you have.

In reply to curtis73:

Yeah, its a bypass chamber type. I'll strip it again and thoroughly check for any cracks etc. I want to have a look at the pusher and check for a slight bend anyway.

I believe the plunger is supposed to stay down until the trigger is released. The larger framing gun and smaller bradder I have both do.

Im starting to think there's a triggering issue. But a leaking bypass chamber also makes sense.

If I manually push the plunger back, it'll Fire 1 nail then fail to fully retract for the next nail. If I hold my finger on the trigger it'll keep trying to fire by its self instead of keeping the plunger at the end of its travel.

I know gun repair. Everything from .177 caliber air rifles to the M61A2 20mm cannon. What do you want to know???