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HVLP Troubleshooting

Why is My HVLP Gun Spitting? — A Complete HVLP Troubleshooting Guide

Is your HVLP gun spitting? Having overheating issues with your turbine? Are you struggling to get that perfect spray pattern and blemish-free finish you want? Join me as I answer these and other burning questions in this ultimate HVLP troubleshooting guide.

HVLP paint sprayers, whether turbine-driven units or a single gun with a compressor combo, offer straightforward operation and consistent finishes. This makes them a firm favorite with professionals, automotive paint sprayers, and home DIY enthusiasts.

They take little preparation time, keep overspray to a minimum, and save you both time and money — until something throws a spanner in the works. Read on to find out how to fix many of the problems you might occasionally experience with an HVLP sprayer or paint gun.

Complete HVLP Unit Troubleshooting

HVLP turbines or compressor-powered machines are a wonderful invention, opening up the world of paint spraying to amateurs and professionals alike. From mighty pneumatic guns to compact handheld units — there’s a model to suit any painting project. Here are some quick fixes you can employ to keep your unit operational.

1. No or Little Material Flow

There’s nothing more frustrating than getting ready to spray something and finding that the paint isn’t being delivered. There are numerous reasons this could be happening, so try some of these remedies.

  • Insufficient paint from the spray gun — turn the paint control knob to the correct position.
  • Clogged nozzle — remove the nozzle and clean any dried paint or debris.
  • Suction tube is blocked — once again, this is a simple cleaning issue. Remove the tube and clear the blockage.
  • Clogged suction tube air vent — clean the vent using a soft-bristled brush.
  • Paint flow is set too low — increase the material flow.
  • Clogged suction tube air vent —make sure the suction tube is fitted as tightly as possible.
  • Paint container fails to build pressure — ensure the paint cup is properly threaded and tight on the unit.
  • Air valve tube isn’t functioning — check the valve seal is in place, and both ends of the tube are connected securely.
  • Missing nozzle seal — occasionally, this seal can work loose and get lost when cleaning. If this has happened, replace the nozzle.
  • Clogged air filter — remove and change the filter for a new one.
  • Material is too thick — thin the coating according to the manufacturer’s instructions.

2. Material Leakages

Apart from costing you money in paint wastage, leaks from your paint system are a sign there is something amiss. Fortunately, it’s generally something you can put right without too much effort.

  • Loose nozzle — tighten the nozzle.
  • Worn nozzle — change the nozzle out for a new one.
  • Missing or worn nozzle seal — inspect the seal and if it’s worn, or has fallen out, replace the nozzle.
  • Dried paint on the air cap or nozzle — clean these components to remove any build-up.
  • Loose guide nut — tighten the nut to prevent leaks.
  • Guide washer is worn — replace the washer.
  • The needle won’t seat because the guide washer is too tight — loosen the guide washer.
  • Spring in the needle assembly is broken — replace it.
  • Needle is damaged or scored — insert a new needle.

3. Sprayed Material Runs or Sags

The last thing you need is paint running or sliding down the wall — spoiling your newly covered surface. There are several causes and solutions for this issue.

  • Material flow is set too high — turn the paint delivery down.
  • Not enough air to atomize material properly — increase the air power.
  • You’re applying too much material - speed up the movement of your spray gun or turn the coating delivery down a notch or two.
  • Blocked nozzle — remove the nozzle and clean away any debris or dried paint.
  • Clogged air filter— check the valve and either clean or replace it.
  • Not enough pressure in the paint container — make sure the paint container is fitted tightly.
  • Material is too thick — thin the coating in line with the manufacturer’s directions.
  • Material is too thin — use a smaller spray tip or make sure the paint is at the correct thickness using a viscosity cup — you may have thinned it down too much.
  • You’re not holding the spray gun at the correct angle or distance from the painting surface — adjust your spraying technique making sure you’re the recommended distance from your target (according to your spray gun guidelines). This is usually somewhere between 4 to 10 inches.
  • Too much overlap — your overlap should be around a third of the width of your spray pattern. Also, don’t forget to trigger on and off at turns.

4. Pulsating Spray Jet

When paint spraying, you want to achieve a steady constant stream of material to obtain a good finish. If you find yours is fluttering in and out, try the following rectifications.

  • You’re running low on paint — refill the material container.
  • Clogged air filter — change the air filter.
  • Disconnected air valve tube — check that both ends of this tube are attached and secure.
  • Needle or nozzle is dirty or damaged — clean these components and replace them if necessary.
  • Paint lid gasket is missing or dirty — check the washer on the paint lid for damage or debris. Replace or clean as required.

5. Excessive Overspray

One thing HVLP spray guns are known for is the reduced amount of overspray they create. If you find yours is painting everything in sight, it could be:

  • You’re holding the gun too far away from the target area — move closer to your surface or item being painted (in line with the recommendations for your model of spray gun).
  • Too much air pressure — turn down the air power setting.

6. Patchy or Light Paint Coverage

Even coverage is key to delivering a professional-looking finish on your paint job. You don’t want to see any gaps or the original coating coming through. Here are some of the reasons this might occur and what to do about it.

  • Slow down the movement of your spray gun — you’ll be spreading the paint too thin if you move too fast.
  • Crank up the material flow — a low setting won’t deliver enough coating.
  • Turn down the air power — too much air pressure affects the atomization.
  • Keep your air cap clean and replace it if worn or damaged — keeping components free from debris and dry paint is a must. As is making sure your air cap is in good working order.

7. Pattern is Heavy on Top or Bottom, or Left or Right

There are two reasons you could be finding that more paint is applied at the edges of your fan pattern. These are the causes and their solutions.

  • The air cap is partially blocked — to ascertain whether this is the cause, spray a test pattern, then rotate the air cap a half turn and repeat. If the defect is inverted, you have an obstruction in the air cap. Clean or replace the air cap as necessary.
  • Obstructed paint tip or debris on paint tip or air cap seat — clean the air cap and paint tip to remove dried paint. If there is fine burring on the tip, you can use 600 grade wet or dry sandpaper to remove it.

8. Spray Gun is Spitting

One question I’m often asked — why is my HVLP spray gun spitting? This is usually due to air being introduced into the system outside of the spray tip and air cap. Check the following:

  • Pick up tube — make sure it’s firmly connected and is fully immersed in your chosen medium.
  • Paint cup — check that the cup is threaded properly on the paint gun and that it’s secured.
  • Fluid nozzle — this is another place air can get in where it shouldn’t. Make sure it’s tight and not worn.
  • Packing nuts and packing — ensure the packing nut is tight and the packings aren’t damaged.
  • Connecting hoses — look for holes or cracks in any hoses. Replace them if necessary, and ensure all are snugly fitted.

HVLP Spray Gun Troubleshooting

We’ve taken a look at problem-solving issues for complete HVLP units, but what if you’re into pneumatic spraying? As in, an HVLP spray gun attached to a compressor. Don’t worry, I’ve got you covered with the following tips and tricks.

1. Gun Won’t Spray

To create an atomized stream of paint, you need air pressure. There are a couple of things that can prevent this from getting through.

  • No air pressure at the gun — check your air supply is on, and the airlines are attached and not damaged.
  • Adjusting screw for the fluid needle is not open enough — open the screw.
  • Material is too heavy for suction feed — increase the fluid pressure at the tank and make sure you have the correct suction feed air cap fitted. If necessary, thin down your fluid or change to a pressure feed paint cup.

2. HVLP Spray Gun is Spitting

You’ve set your Titan paint sprayer up and are all ready to begin work when you notice that material is not drawing through the system, although it’s set to PRIME. The main culprit of this is generally a blockage somewhere in the system. These are the parts you need to check:

  • Wrong needle fitted to the spray gun — consult the manufacturer’s needle/tip chart and select the appropriate one.
  • Needle is worn — replace the needle.
  • Worn fluid tip — pop a new fluid tip on the gun.
  • Fluid tip isn’t fitted properly and paint builds up inside the air cap between spraying — tighten it and make sure it’s seated correctly.
  • Clogged fluid tip — clean any dirt, dried paint, or debris from the tip.

3. Air Cap Leaks When Gun Isn’t Triggered

When the trigger of your spray gun isn’t engaged, you shouldn’t hear any air escaping from the spray tip. If you do, take the following step.

  • Remove and clean the air valve, seating, and shaft — contamination can prevent the air valve from sealing.

4. Material Leaks Slowly From Fluid Tip and Needle Seat

A bit like Chinese water torture, a slow leak can be very annoying. To stop permanent slow leakage from your needle seating or spray tip, check out these fixes.

  • Damaged, worn, or scored internal seat on the tip — replace the tip.
  • Outer profile of the needle is worn or damaged — renew the needle.
  • The needle and tip mating surfaces are contaminated — this prevents them from sealing. Give them a thorough clean.
  • Mismatched fluid tip and needle — ensure that the needle and tip are compatible.
  • Needle doesn’t move freely — remove the needle. Clean and lubricate it.
  • Packing on the needle is too tight — loosen the packing.

5. Major Material Leak or Coating Jetting From Fluid Tip

A slow drip might be an inconvenience, but a major leak is a worry — luckily, there are actions you can take to get your spray gun in working order again. Take a look at these reasons and solutions for the issue.

  • Contaminated needle, tip, or seat prevents a seal — take out the tip and needle and clean them, along with the internal gun surfaces they’re in contact with.
  • Wrong fluid tip for the needle you have fitted — check the needle and tip are compatible sizes.
  • Fluid needle is bound up or sticking — remove and clean the fluid needle and the shaft. Lubricate and loosen the needle packing if necessary.

6. Material Build-Up On the Fluid Tip or Air Cap

Certain things can result in a build-up of fluid on the tip of your spray gun, preventing it from performing well. Explore these options to sort it out.

  • Incorrectly fitted fluid tip — make sure the tip is correctly fitted in your spray gun and tighten it.
  • Needle or fluid tip packing is loose or worn — inspect for damage or a blockage and clean or replace.
  • Damaged air cap holes — change out the air cap for a new one.
  • Build-up due to bounce back over time — clean your gun head thoroughly.

7. Air Leak From Needle Exit Point in the Upper Handle

There are seals at the point where the needle exits the spray gun. If these get damaged or worn, an air leak is a result. When this happens, replace the seals to make it air-tight again.

8. Jammed Air Cap

A retaining ring holds your air cap securely in place on your spray gun. To clean the gun or change the air cap, you need to be able to remove this component. If the threads have become dirty, the gun head will require soaking in a solvent solution to remove dried paint.

When this fails, or if the retaining ring looks damaged or deformed, you may need to cut it off and replace it. This could mean the baffle will need to be changed out as well.

9. Trigger Doesn’t Move Smoothly

A stiff trigger can leave you with hand fatigue, or at worst, prevent your gun from spraying. To alleviate the issue, identify the cause and implement the solution as follows:

  • Bent air valve stem — Bent air valve stem.
  • Air valve stem is dirty — remove this element. Clean and replace it.
  • Fluid needle shaft is grimy — take out the needle and clean the needle shaft.
  • Trigger bearing screw is soiled — undo the screw, remove it, and clean it.
  • Packing on the needle is too tight — loosen the packing or the packing nut.

10. Fan Control Issues

Does your control knob for the fan pattern fail to turn? Maybe you can’t switch between an oval or round spray pattern? A few simple things can allow you to adjust your fan delivery again to where you want it.

  • Replace the internal o-rings on the top rear of the spray gun — these may have swollen or been damaged.
  • Remove the knob, clean it and the threads thoroughly — dried paint or other debris will interfere with its smooth operation.
  • Remove and check the baffle and fluid tip to ensure they are fitted correctly — if they’re damaged or not inserted quite right, you won’t be able to switch between patterns.
  • Replace a damaged air baffle chimney — again, if it’s damaged, it affects your ability to select the correct spray.

11. Air Control Valve Won’t Turn or is Sluggish

A valve that controls the amount of air pressure delivered to atomize your paint is located on the handle of spray guns. If this becomes clogged up around the threads, or the o-rings are damaged or swollen, it won’t work. Be sure to clean these areas well and replace any damaged or worn parts.

12. Air Valve Problems

This valve controls the delivery of air into the paint stream. As a result, paint is atomized and dispensed as a fine spray. When it fails in any way, your spray doesn’t perform. Here are some of the things that can go wrong and how to put them right.

  • Sluggishness to turn on or off when the trigger is released or pulled — check the air stem valve for kinks. If damaged, replace. If it only shows signs of debris or build-up then clean it.
  • Remove the knob, clean it and the threads thoroughly — dried paint or other debris will interfere with its smooth operation.
  • Air is leaking from the air valve stem — examine the seal for damage, and replace it.
  • Air valve won’t operate when the trigger is pulled — a bent air stem or contamination in the system will prevent the air valve from sliding into the body. Either clean or replace it as necessary.

When All Else Fails


HVLP spray guns are reliable and durable, but there are times when a quick fix doesn’t work. If this happens, contact the manufacturer to see if they can help find a tailored solution for your particular gun.

Unfortunately, there are occasions when you have to bite the bullet and invest in a new spray gun — in which case, you could take a look at the top picks I’ve listed.

So, when someone asks ‘is your HVLP gun spitting?’ You can happily tell them, not anymore — Tool Nerds HVLP spray gun troubleshooting tips and tricks helped me sort the problem out.

Our Top Pick

Wagner FLEXiO 5000


Our Rating: 4.9

Featuring Wagner’s patented X-Boost turbine and offering variable power output, this machine is as capable of propelling low-density mediums as it is high-viscosity paints. It also boasts a lengthy 11.5-foot non-kinking hose, permitting plenty of movement from the base unit.

Two nozzle tips accompany the FLEXiO 5000, providing a fine finish and rapid coverage. Plus, once you’ve finished spraying and cleaned your unit, on-board storage keeps everything in one place.

Features

  • Upgraded version of Wagner's iSpray nozzle.
  • Adjustable material flow control and spray width.
  • Lock-N-Go system — speedy dismantling and fuss-free cleaning.
  • 0.85 and 1.5-quart paint cups included.

HVLP — Product Comparison Table

IMAGE PRODUCT DETAILS
  • Paint cup: 1.5 quarts / 0.85-quart
  • Format: External turbine
  • Nozzles: Detail and iSpray
  • Weight: 15.3 pounds

Features

  • Includes two paint containers and nozzles.
  • Dual speed.
  • Turbine casing functions as a storage box.

Product Rating: 4.9/5

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  • Paint cup: 0.84-quart
  • Format: Handheld turbine
  • Nozzle: 2 mm
  • Weight: 3.1 pounds

Features

  • Fine-finish brass tip.
  • Turbine with 400-watts of power.
  • Ideal for the DIY novice sprayer.

Product Rating: 4.9/5

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  • Paint cup: 0.85-quart
  • Format: Handheld turbine
  • Nozzle: Control Finish
  • Weight: 3 pounds

Features

  • Delivers 1.25 liters per minute.
  • Multi-medium compatible.
  • Ergonomic handle — prevents tired hands.

Product Rating: 4.6/5

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HVLP Spray Gun Kit — Product Comparison Table

IMAGE PRODUCT DETAILS
  • Medium feed: Gravity
  • Tip size: 11 spray tips ranging from 1.2 to 2.5 mm
  • Cup material: Aluminum

Features

  • Three paint guns, cleaning tools, multiple spray tips, and a wrench.
  • Suitable for professionals and amateurs.
  • Durable customized carry case included.

Product Rating: 4.8/5

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  • Medium feed: Gravity
  • Tip size: 1.0, 1.4, and 1.7 mm
  • Cup material: Aluminum

Features

  • Adjustable air intake, fan pattern, and paint flow.
  • Reduced overspray.
  • Two-step trigger.

Product Rating: 4.0/5

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