On Sunday, June 6, 2010 at 5:06:45 PM UTC-5, Steve Turner wrote:
After a fair number of positive reviews in this group I decided to pick up this
spray gun a few months ago from Harbor Freight:

http://www.harborfreight.com/air-too...ay-gun-86.html

I used it once (probably to spray some clear lacquer; don't remember), cleaned
it (I've been using and cleaning out spray guns for over 30 years, so I'm no
dummy at this), and put it away. Pulled it back out this morning (that's what
she said) and tried to spray some Zinsser white shellac primer, and... nothing.
Lots of air flow, but no white fluid is coming out of the nozzle (that's what
she sai... er, never mind). Thinking there must be a clog or obstruction
somewhere, I started disassembling things and checking for problems, but found
nothing. Before I start talking specifics, those who pretend to care about my
piddly little problem might want to refer to the parts listing on page 12 of
the product manual:

http://manuals.harborfreight.com/manuals/0-999/86.pdf

Ok, so there are no obstructions anywhe air is flowing from all the ports
in both the air cap and fluid nozzle; I've adjusted the fan adjusting screw
just far enough out so that the trigger has full travel (but no more) which
allows the needle to open according to the trigger pressure, and it retracts to
the fully closed position when the trigger is released. The volume adjusting
screw (which controls the amount of air flow to the "wings" of the air cap,
which in turn controls the amount of "fan-out" to the spray pattern) is working
properly, and you can feel the air flow from the air cap change as adjustments
are made; I was running it wide open, but its position makes no difference.

No matter how I adjust any of those contraptions, no fluid is being pulled from
the cup. And yes, the pressure release air hole in the top of the cup is open,
and the shellac is sufficiently thinned for spraying. In fact, the cup can be
filled with straight denatured alcohol and it makes no difference; no siphoning
action is occurring. I can even remove the cup and stick the siphon tube into
a separate container of denatured alcohol, and still nothing. HOWEVER, if I
remove the gun from the cup, turn it upside down and fill the siphon tube with
fluid, VIOLA - It sprays! If I disconnect the gun from the air supply, fill
the siphon tube with thinner (still upside down), and actuate the trigger, a
steady stream of thinner runs out the nozzle and is depleted, just as I would
expect. EVERYTHING is working as I'd expect, except no siphon action is
occurring; I'm befuddled.

Any ideas?

--
Any given amount of traffic flow, no matter how
sparse, will expand to fill all available lanes.
To reply, eat the taco.
http://www.flickr.com/photos/bbqboyee/


Or it could be something as simple as a blocked vent hole.