GX390 Shakes

Hey guys, got a question for some more experienced guys. I have a gx390 4 gpm that starts fine, has proper pressure and flow but in my personal opnion and my helpers it just seems the thing shakes like its no ones business. Any thoughts on why that would happen or what i should look for. Any help appreciated. I will be using it tomorrow and if i can upload a video i will. Thanks in advance.

How old is the engine, has it always done this, and please post a video. A guess would be it’s possible it could be the balance shaft or the bearings for it are bad.

I’d like to see a video too. Are experiencing any problems, like loss of pressure or surging?

Gotta look at all the basics first. Air filter, spark plug, oil, fuel sediment bowl next to the carb bowl, carb bowl, or carb itself. Maybe sure the engine bolts are tight to the frame.

also on another machine I have , I have an unloader problem which was making the engine shake

Make sure everything is tight, no exhaust leaks, even check plug is not cross threaded.

Hey guys thanks for the reply. I took a video but as per usual when im filming it doesnt do it and it also wont let upload a video here. i will try and explain something interesting i saw and not sure thats something to do with it.

The machine has a pressure guage and when i let go of the trigger the pressure goes down to Zero, but sometimes i notice it gets stuck at 4000 or 3500 and thats when it shakes like a salt shaker. The hose also just feels weird like it pulsates or something like that. If i open and close the trigger the pressure goes back to zero and no more “pulsating”.

Upload your videos to Youtube (free) and share the link here.

The first thing I would do is try replacing the unloader.

Make sure your supply is adequate.

Guys so i figured out its my bypass going haywire. I will be changing it and it will hopefully stop doing that nonsense

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Had a issue with mine today. Got a alkota unit while i get my pther unit overhauled and my flatbed built. Came with a chem injector etc on it. One of the fittings had a ball inside that decided to get stuck. Ended up pulling the whole chemical injector off and replumbing everything to the unloader. Was a PITA to figure out and a PITA to fix since they locktoghted everything up the butt and hard to get wrenches inbetween everything