How to Use A Smoke Machine to Detect EVAP Leaks

Leaks are one of the most common problems that can take place in an automobile. You may be able to see fluid on the ground underneath your car. However, vapor can leak on the inside of your engine as well. If there is a leak in the engine, the car will not run properly. That’s where the EVAP smoke machine comes in. Helping you detect those dangerous leaks.

What is an EVAP Smoke Machine?

AN EVAP smoke machine tests the Evaporative Emission Control system for leaks.

The EVAP system protects the components in your car’s fuel system from leaking dangerous vapors into the air. Vapors from fuel contain hydrocarbons which is what causes smog.

You can reduce your carbon footprint significantly if your EVAP system works properly.

There are some very sophisticated vehicles manufactured today that have self-testing EVAP systems. Even those systems are somewhat limited in their ability to find certain leaks.

How EVAP Smoke Machines Work

A smoke test is one of the most accurate ways to find out if an automobile has too much pressure in the EVAP system or if there is a leak in one of the components. It is easy to do as well. All you need to do is blow smoke into the various parts of the system to see if they are leaking.

When you blow smoke into a closed container, the smoke should stay in the container. If there is a hole in that container, smoke will leak out.

An EVAP system works by filling all the various components of an EVAP system with smoke and if you see smoke coming out of any one of those components, you will know that you have a leak.

The EVAP system has many different parts, and each component is critical to the operation of your vehicle.

What It Looks Like (Insert Diagram)

A smoke machine has a flow gauge that can control the amount of smoke coming out of the machine. It has a pressure gauge as well. It has a hose with a nozzle attached to it where the smoke comes out. It has two hoses in the back that attach to the battery.

How to Use an EVAP Smoke Machine

Before you begin your test should visually inspect all of the components of the EVAP system for leaks. If you do not see any, you should begin your test.

A smoke machine must always be used when the car is turned off.  If you have a scanner for your car, it will help in the smoke detection process.

You will then need to prep your vehicle. by closing off certain solenoids. Many of the components of your car’s EVAP System contain a solenoid. A solenoidis an electromagnet that generates a magnetic field via a coil wound into a helix that has been tightly packed.

You will need to close the purge solenoid and gas cap before you attach your smoke machine to your car. As well as close the vent solenoid after connecting and turning on the smoke machine.

Here is the step-by-step guide on how to use the EVAP smoke machine.

1. Seal The Purge Solenoid

The purge solenoid is located in the engine of your vehicle. It will be connected to the intake manifold in the car’s engine. It should already be closed when the car is off, but if it is not you should close it.

2. Seal Gas Cap

Fasten and secure the gas cap. If it is loose, the test will show that it is leaking. If you know you have a bad gas cap, replace it before you begin the test.

3. Attach the Smoke Machine to the Battery

Attach the EVAP smoke machine to the car by hooking the positive cable and the negative cable to the battery.

4. Turn The Smoke Machine On

Turn the smoke machine on and wait a few moments for the smoke to come out of the nozzle. When you see smoke coming out of the nozzle, find a point of entry for your test.

Most mechanics will use the purge solenoid to do this. First, unplug the purge solenoid, then attach an adaptor to the purge solenoid. The adaptor will protect the solenoid during the test.

You will find this adaptor in a standard fuel pressure test kit. Then attach a cone fitting to the smoke machine’s nozzle and attach the cone fitting to the adaptor.

5. Close the Vent Solenoid

The vent solenoid is in the back of the vehicle. It’s usually opened when the car is off. You will find it right near the gas tank. You can close the vent solenoid with a scan tool.

Simply go into your functional tools on your scanner, and you will see an option to close the vent solenoid. You will see the gas tank pressure beginning to climb once you have closed it. If you do not have a scan tool you can manually close it.

Now, look at the leak gauge on the smoke test machine. The leak gauge will resemble a thermometer with a ball inside. If the ball rises to the top, you have a leak.

6. Look for Your Leak

Now you should grab your flashlight and look for your leak. When you find the leak, you will notice which part of your EVAP system needs to be repaired. There are several components of the EVAC system that may contain leaks.

Best EVAP Smoke Machines

The very best smoke machines include every tool that you could need to find leaks in your car. A universal cone adaptor and a high-powered flashlight with batteries. It is constructed of solid thick metal. It should have a warranty of at least a year and come with detailed instructions on how to use each of the tools that it includes.

Here are several recommendations for smoke machines:

EVAPro Smoke Machine Evaporative System Tester 2000E

This easy-to-use machine comes with several adapters. It is constructed of hearty steel and has a 25-foot hose. It even comes with a smoke diffuser so it should be fast and easy to use. It contains the oil you need to run the machine. You should be able to perform 500 tests for every container of oil that you use.

The AutoLine Pro EVAP Vacuum Automotive Smoke Machine Leak Detector

This machine was designed with the user’s safety in mind. The oil in it is Nitrogen-based for safe EVAP testing. Not only is a flashlight provided in the kit, but you will also see a fluorescent dye at the location of the leaks.

Vacutec wv605

The best thing about this handy machine is its ability to detect the tiniest of leaks. You can test with or without smoke and it even comes with a two-year warranty.

Buying Guide for EVAP Smoke Machines

Whenever you feel like an EVAP smoke machine is a right investment for you, there are a few things to keep in mind.

Where Can I Buy a Smoke Machine?

You can buy a smoke machine wherever auto parts are sold. You will find reasonably priced easy to use machines at the following retailers:

  • Amazon,
  • eBay
  • Autozone,
  • Repco,
  • Harbor Freight
  • Walmart

However, the largest selection of smoke detectors is at AutoZone, mainly because it is a store dedicated to auto supplies of course. The salespeople are also likely to know more about the machines than they would at a big box store, so it’s the better option if you’re not sure about what you are getting.

Although Walmart and Amazon are likely to have the least expensive machines, Autozone will have a wider selection and offer the best of them.

How Much Does a Smoke Machine Cost?

A smoke machine can run anywhere from $60 to $1500. This is a worthwhile investment when you consider what auto repairs will run you if your EVAP system should stop working.

The cost for the average EVAP system repair is about $300. The parts are normally more expensive than the labor. The exact cost of the repair or replacement will depend upon which part of the leak system needs to be repaired.

Smoke Testing

A smoke test can cost anywhere from $30 to $150 depending on your make and model of vehicle. They take between 30 minutes and 60 minutes to perform. You can find shops that offer a smoke test on the Autozone website. You can also visit the AAA website to find a list of approved mechanics in your area and the services that they perform.

Can You Make a Homemade EVAP Smoke Machine?

The best news about the EVAP smoke machine is you don’t necessarily have to buy one to have one. You can make your own if you are low on funds, or if you just love to put your hands to work.

You will need several parts including:

  • An air compressor
  • A paint can
  • Incense
  • Screw Driver
  • Lighter
  • Magnetic bowl
  • A flat lid for the paint can with two holes drilled into it

First, secure two air fittings into the holes in the lid. Attach 3 to six feet of 3/8 inch tubing to the air fittings. Break your incense apart and light them. After that, wait until they are smoky and place them in the paint can.

Whenever you’re done with that, place the bowl in the paint can and put the lid on to the can as well. Now turn the air compressor regulator down as low as it will go. Hook the hose of the compressor to your smoke machine and turn the air compressor up very slowly until you see smoke.

Finally, insert the hose into each component of our EVAP system. If any smoke comes out, you have a leak as well as your DIY smoke machine. We hope only for the latter of course.


Here are a few other questions you may have about EVAP smoke machines.

What is the best EVAP smoke machine?

The Autoline Pro machine made several best EVAP smoke machine lists for the year 2020.

Who makes the best EVAP smoke machines?

The Autoline Pro Smoke Machine is made by Autoline Pro

Does Autozone do smoke tests?

No, AutoZone does not perform the tests. However, they can recommend a qualified mechanic.

How do you check for EVAP leaks without a smoke machine?

Mechanics sometimes use a vacuum hand pump and test each individual line one at a time for the proper amount of pressure.

What is the advantage of using a smoke machine to diagnose EVAP leaks?

A smoke machine is fast, easy, and accurate. You will find more leaks using a smoke machine than any other method of testing for an EVAP system.

Final Thoughts

Your car is one of your most necessary possessions and you won’t be able to drive it if it does not pass an emissions test. Making sure your EVAP system is working properly will ensure that your carbon footprint is small and your car runs well.

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Author: Dave Johnston

Dave is a hands-on automotive technician with experience in performing service, diagnostics, and repairs on domestic and imported vehicles. He enjoys writing and sharing his knowledge far and wide.

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