Tradesman 8550 16 gauge nailer

6 years 11 months ago #2039 by Larryg
Tradesman 8550 16 gauge nailer was created by Larryg
The plunger / hammer on the gun was stuck down so I took it apart and cleaned it up. Found some sludge in it from like oil and moisture. Not really to bad though. After I put it back together it fires multiple times. Instead of firing just one nail it rapid fires several times. If I pull the trigger and hold it, it fires once. But when I release the trigger is when it fires multiple times. I did order a new trigger / switch assembly for it, but that was not the problem.
What am I missing here? I've been over the assembly diagram a thousand times. I'm sure it's something I've missed but I'm just not seeing it.
Any help would be greatly appreciated.

PS - Someone told me that Porter Cable made this gun. Not sure if that's true or not but that's what I heard.

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6 years 11 months ago #2042 by MTR-Admin
Replied by MTR-Admin on topic Tradesman 8550 16 gauge nailer
Thanks for the post Larryg,

I can't find much information on this brad nailer anywhere, but I found a photo and it looks like a pretty typical nailer. Porter Cable does make a similar model so that may be true.

Without seeing it or properly diagnosing it I can only give you some general advice, but it sounds like a trigger issue to me.

Since there is not much information on this tool so I can't really see what the setup is, but from my experience it seems to me the first thing to check would be the trigger and safety assembly, this is what actuates the tool to "fire" or "cycle". If there are multiple firings or cycles air pressure must pass through the trigger valve for this to happen. The tool should be disassembled and thoroughly cleaned, check all o-rings,seals and hardware for wear or damage and replace as necessary. When reassembling lubricate all seals, o-rings and moving parts with good quality lubricant.
Take a look at the trigger valve and the o-ring in (and around) the valve, first. I think you'll find that a good cleaning (and lubrication) will fix the problem.

- MTR

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6 years 11 months ago #2043 by Larryg
Replied by Larryg on topic Tradesman 8550 16 gauge nailer
Thank you so much for your reply. Sorry so long in getting back with you. I've not got a chance to get back to the nailer yet. Hopefully this weekend. The trigger valve was my first thought so I did replace it with a new one. It still does the same thing. So given what you said I need to really look into the safety mechanism. That seems to be the most likely culprit at this point and it is not the easiest system to get back together. Will let you know. Thanks again

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6 years 11 months ago #2044 by MTR-Admin
Replied by MTR-Admin on topic Tradesman 8550 16 gauge nailer
Sounds good, and let us know what you find when you inspect it further!

- MTR

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6 years 10 months ago #2049 by Larryg
Replied by Larryg on topic Tradesman 8550 16 gauge nailer
OK this thing is driving me crazy. I'm confident that the safety mechanism is correct and the new trigger valve is in, but it still multi-fires. When the trigger is released it mimics an impact wrench until all of the air in the gun is released. It may fire 20 ~ 30 times.
And just an fyi I'm not new to this stuff. I am a mechanic - I've rebuilt several impacts down through the years. And a few compressor's. But this is my first nail gun.

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6 years 10 months ago #2050 by MTR-Admin
Replied by MTR-Admin on topic Tradesman 8550 16 gauge nailer
I still think there is a trigger valve issue, honestly. - Air pressure must pass through the trigger valve into the port to pressurize the tool so that it will fire. If it is firing multiple times then the trigger valve is allowing air pressure to flow for some reason. My first guess is that something went wrong with the installation. I'm not saying it certainly is installed incorrectly, but I would certainly remove it to confirm. Make sure all of the o-rings are lubricated very well and weren't damaged when the trigger valve was installed. Also insert a few drops of pneumatic tool oil (if you haven't already).

- MTR

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