Air bubbling up in cup when air trigger is pulled this is a gravity fed hvlp spray gun

I've found over the years the least amount of times you can tear a spray gun completely apart the better. Usually a real good 'flushing' with lacquer thinner will suffice. I will take the air cap off and let it soak in thinner to dislodge any build up but other than that, I simply run thinner thru till it runs clear out the tip.

I also 'back flush' which involves having thinner in the cup and the air supply hose attached. the air pressure should be adjusted quite a bit lower than what you use for spraying paint.

Then you place a clean shop towel or rag over the air cap of the gun and pull the trigger. This forces air back into the paint cup 'back flushing' the gun. Then take the rag away from the cap and pull the trigger again to run thinner thru the gun the normal way.

IF you still want to tear the gun apart for cleaning you can hopefully get some idea with this video link;

Quick Easy Way to Clean HVLP Spray Gun

Hope this helps.

when you pull the trigger can u see the needle moving backward? if so, then it's either the paint is too thick compare to the nozzle size or the passage for paint is blocked. try to take the nozzle, needle and the cup off and give it a good clean!

Check the packing nut on the trigger where the neddle valve slides through the trigger a bad seal there will make this happen

Fluid tip probably not tight, or the seals in the baffle are leaking.

spray gun is cloged (clean it!) also check gaskets in gun and vent hole in cup lid ( could be cloged)

Check the nozzle and housing for old paint build up

most spray guns are basically the same gravity feed is no different, air pressure into gun and out nozzle,spray pattern fan to spot and last the amount of fluid comin out of cup to the nozzle.

It depends on the air cap\tip you are shooting with. For instance the 110 air cap is a standard compliant style. Were as the 105 and 115 are a HVLP style.

Sounds like you need to completly dissasemble and clean thorougly.

Does it come with instructions? The material thickness is VERY IMPORTANT when choozing the proper nozzle.