i just got my lvlp gun in mail to shoot guitars with, the instructions online say with trigger pulled it should be around 26PSI
the air valve next to the compressor fitting is is sealed closed & does not open, i connected it to my compressor & with the regilator at about 30 or 40 when i press the gun air comes out plenty but it goes to 0...not sure if the saying on the gun next to the sealed air adjustment valve screw means anything but it says
AIR IN 16-19 PSI
(1.1-1.3 bar)
DYNAMIC

i put some thinner in it & it works...i will only be using it for clear...

I will be using it tomorrow im hoping this is normal...ive tryed 2 regulators...

Suggest you go to Home Depot or similar and pick up a cheap threaded air gauge and "T" fitting, maybe short whip hose as well with quick-disconnects -- make up a temp gauge to measure PSI at gun handle.

With trigger pulled that gauge should read around 18PSI. Here's a post where I describe testing to make sure your compressor can handle the gun you are using:

viewtopic.php?p=174276#p174276

In your case the target PSI is 18.

the company says working pressure should be 25 which is what i was told from another forum member give or take...
i set the output of my compressor to 35-40 my air gauge on the gun i added says the same...when i press the gun the gauge on my comprerssor will drop to 26ish but the gun says 0, i have 3 gauges for my gun ive tried...2 that i had from HF & i just bought a husky one from HD....all the same...
excuse my ignorance here i just dont want to get overspray when i paint tomorrow...that was the whole purpose of buying this gun...

Crank the regulator at the compress up to just below its highest limit.
Then pull the trigger full open on the gun and dial in your psi at the gun.
You want the 18 - 25 psi reading at the gun while spraying with the trigger full open.

well i painted 2 guitar bodies & it didnt go any better than the HF purple gun i had....
this gun is either a defect or does not work well with my compressor or im just an idiot....its prob im just an idiot.....
i cranked the compressor to 120 PSI....the gauge on my gun said the same...when i pull the trigger the gauge goes just over 0...& i can feel when i tested on paper it was way to high....the paper flew out of my hand when i tryed to check the fan length...at that point i figured the regulator on my guns reading is just not going to work for me...i put the gauge on my compressor at 35 & when i pulled the trigger it went down to 26 which is what i need...but my first coat didnt even atomize....just little dots....im guessing the hose length takes away some...so i turned my compressor up to 50 & played with the paint knob in the back of my gun as best as i could...major clear runs as something was still off....way to much material or air not sure....one thing i just noticed is the specs of the gun says min 3 hp compressor & mine is 2.....dont think it matters though....for the second & third coat i kinda had it going well i think....i have to paint another guitar body on sunday...i wrote down my settings...
oh well....

Something is wrong if the pressure at the gun handle drops to zero when you pull the trigger.

Give us the following information:

1. Make and model compressor.
2. CFM rating of compressor at PSI stated, on sticker or badge on compressor.
3. Exactly what the supply chain is from the output of compressor to the handle of the gun. Type and diameter of hose, any valves or gauges, tell us everything.
4. Take photos of the setup and post here.

Once this is squared away and you are able to see pressure at the gun handle with trigger pulled you will need to follow the procedure I gave earlier (link to that other thread) to see if the compressor can keep up with the gun.

Sound frustrating. Drink a beer or two and then come back to it.

Do you have a regulator at the gun? Not just a dial that shows you PSI, but a dial and a knob that allows you to adjust the amount of air coming out of the gun? See attached picture. The dial is facing up and the knob is facing towards the table.



Even the cheap ones from HF or Home Depot work OK, esspecially with low CFM guns. I do not use the air adjuster knob on the gun. I just leave it wide open and use the add on regulator.

Crank the PSI up to say 60PSI at the compressor and turn the knob at the gun all the way down. Pull the trigger and nothing should come out of the gun. Keep the trigger pulled and open the valve at the gun until the dial reads the desired PSI.

For small parts painted in short bursts I do not think your 3HP compressor is a problem. And because what you said about having too much air at the gun I don't think you have any restrictions or too much line.

So, I think adding a regulator at the gun will get you in the ball park. After that it sounds like you know what you are looking for as far as gun setup.

Another hint once you get the new gun going. Try to run the PSI in your line as low as possible and still maintain the desired PSI at the gun (+3 PSI or so) with the valve at the gun full open. Too muck PSI in the line will make it act like a balloon. When you first pull the trigger there will be a burst of higher than normal pressure air coming thru the gun, which can throw you off.

chris wrote:Something is wrong if the pressure at the gun handle drops to zero when you pull the trigger.

Give us the following information:

1. Make and model compressor.
2. CFM rating of compressor at PSI stated, on sticker or badge on compressor.
3. Exactly what the supply chain is from the output of compressor to the handle of the gun. Type and diameter of hose, any valves or gauges, tell us everything.
4. Take photos of the setup and post here.

Once this is squared away and you are able to see pressure at the gun handle with trigger pulled you will need to follow the procedure I gave earlier (link to that other thread) to see if the compressor can keep up with the gun.

Thanks for trying Chris....
here is my compressor:

http://www.harborfreight.com/8-gal-2-hp ... 69667.html

I have a 1/4 inch hose i believe & i think thats what the comp says to use...

here is a video i made....i have tryed without the filter & with 3 diff regualtors...i have tryed when the regulator is at zero to lift it up & it wont...i have nothing between the hose & red filter in the vid...just the output gauge of the comp...i have tryed to put the comp at 125 psi as high as it goes & still nothing ...instead of 0 it goes to about 5 at that point...

https://www.youtube.com/watch?v=kiTy3aRt1Nc

ok, a few things.

I am not sure what the CFM requirement on the gun is but that compressor claims it's putting out 5.5 at 40PSI. Putting that through the Harbor Freight truth-o-matic filter it's probably a 3.5 to 4 CFM compressor. Look at the specs on the gun and see if that is enough air to drive the gun.

The supply hose from the compressor needs to be a 3/8" i.d. (inner diameter) hose, so it's a 'thick' hose -- not that cheap plastic bicycle pump type of hose that those compressors usually come with.

Get rid of that orange filter, it is contributing to this problem.

The pressure is dropping to zero because the volume is not there to maintain the pressure. Think about it like this: if you turn your garden hose valve on just a tiny amount and don't pull the spray trigger, after a few seconds you will have a lot of water pressure in that hose -- you pull the trigger and get a good strong blast for about 2 seconds, then it drops off. It drops off because the water volume is not there to maintain the pressure. Open up the valve all the way, and you get constant volume and good pressure.

Air is almost exactly the same.

I don't have time right now to record my own video but I grabbed the first one on YouTube I could find. I have no idea who these two guys are but please click here and watch at the 6 minute mark and see how his gun gauge is responding as the trigger is pulled. (You will probably have to click 'x' to close the advertisement YouTube shows over the video...)

This is what we expect, trigger fully depressed and compressor able to maintain the working pressure the gun requires at the handle, whatever we dial it in at.

If you do everything I told you and it is still nosediving to zero I'm sorry to say it but the compressor is not going to work out for you, with this particular gun.