My Im 90i twist nail gun will not fire and the fan runs continuously

don't have any of them but sounds jammed from sitting . too dry. anyplace tto put oil for the driver to move?

Your question isn't specific enough. Multiple things need to work together to fire a gas fired nail gun;
First the obvious user faults;
Low battery
Low gas
Nail guide jam

Not so obvious;
Broken/worn return springs (nail guide and firing bolt)
Faulty micro switches
Bent or impacted internal mechanism
Fan fault
Ignition or spark fault
Dirty or damaged ignition chamber (just like a car piston, cylinder and rings)
Faulty micro controller and ignition circuitry

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.

replace circuit mold assembly or spark unit its probably the spark unit

your gas has expired , look at bottom of canister check the date. buy new gas also make sure cap on gas canister is down all the way till it snapps new gas doesnt come with cap down all the way

Several of my customers are having the same problem here in New Mexico. If your air temperature is around 95 degrees or higher the plastic the caps are made of becomes too pliable to break off when the nail is fired through it. If you cool or freeze the cap roll, the caps will break off however this usually impractical. Get in the habit of moving the gun forward after firing a nail/cap to break the cap off. If you pull up or backwards you get a string of caps pulled out of the gun.

Any time these guns become intermittent or stop firing but the fan still runs, the first the to check is the expiration date on the gas cartridges. The do expire and this will make the gun work inconsistently or not at all.

Nail guns either have a switch or a seperate trigger assembly for two options - automatic, or 'bump' fire, and sequential fire. Sequential firing may be best for you since the nose must be fully depressed and the trigger pulled for each nail.

If you're stuck with bump firing, practice your technique. Double fires often occur when the workpiece bounces back into the nose of the gun; learn to 'bounce' the gun off the material to avoid this second contact.

If you're getting double fires in sequential mode, the problem could be more serious. I keep a can of aerosol silicone lubricant on hand to clean and lubricate the feed mechanism and magazine. Make sure your tool is clean and lubricated before each use, including the 3-5 drops on the air coupling.

Check that your air pressure is not set too high. Overdriving nails reduces their effectiveness and can cause tool malfunction.

This problem could also be caused by worn out O-rings or other parts within the tool. If you're not comfortable servicing the tool yourself, take it in for repair/maintenance work.

Another important thing to remember: With tools like this, you get what you pay for. A cheap nailgun will never function as well as a quality nailgun.

Does the fan run and the light blink ont he nailer? I have one that I just bought. I put in the wrong type of nails and got one stuck. I had to take the front apart to clear it and now the damm thing wont fire. The green light blinks and the gas cartridge is basically full, even the fan does run after I release the push lever, but no fire???

I wonder if yours is the same as mine did fire for a couple nails first just fine then got jammed...

I will try to charge the battery more.... MAybe like yours it needs a strong charge for the spark...
Russ

Professional-grade varieties are automatic, and fire a nail directly upon pulling the trigger. A semi-automatic nail gun is more appropriate for beginners, since it requires a two step process: pull the trigger and then tap the barrel against the wood. This safety feature protects the user from accidentally firing a nail gun and injuring himself or others.