Video: DIY Fuel Injector Testing Rig — Can You Do Better?

The Do-It-Yourself spirit is the heart of hot-rodding, as back in the day, the parts and pieces simply didn’t exist in a paper catalogue (remember those?) or on a website. While modern technology has intimidated some into thinking that the days of doing things yourself are gone, the spirit is still alive and well with many of you; the advanced technology only allowing you to get more creative. Case in point: this video of a homemade fuel injector tester that we recently ran across on YouTube.

This creative guy uses a modified small propane gas cylinder (empty, of course) as his pressure vessel. After removing the valve core and purging the cylinder of fumes, he then drilled out the neck and created a second hole at the base of the container. After threading and brazing a simple ¼-inch NPT- 3/8-inch barb fitting into the lower hole, he crafted a charging port out of a brass cap that matched the cylinder’s threads and a standard tire valve stem assembly

This DIY fuel injector tester consists of some pretty mundane parts, and allows you to check spray pattern and diagnose leaky, dirty, clogged, and dead injectors. It also allows you to flush and back-flush injectors.

Then to attach the fuel injector to his pressure vessel, an assortment of fittings and tubing that were laying around were used. As the video’s creator noted, there are many ways to skin that cat, and he chose the cheapest route, which is mostly hose clamps and reinforced tubing. The one part that is pretty important and probably won’t be lying around is the quarter-turn shut-off valve, which is critical in order to be able to swap injectors while the system is pressurized.

For the electrical side of things, simple is the name of the game. A pair of test leads with a pair alligator clips connected to the fuel injector connectors at one end, and a 12-volt source at the other, with a common momentary single-pole, single-throw switch spliced into one of the leads completes the test rig. At least that completes the test rig in the video…

As you can see, the spray pattern shape and quality is easily seen using mineral spirits or kerosene as a test medium.

As we watched this video, our wheels started turning and we started thinking about how we could improve on the design. First, a larger pressure vessel with a pressure gauge fitted would be very useful in setting and adjusting the operating pressure for actual flow testing an injector. While industry standard test pressure for flow numbers is 43 psi, it’s not uncommon for applications in the real world to run greater injector pressure. Most air compressors have output regulators on them already, and a hard-mounted connection to the pressure vessel would allow the pressure of the fluid supplied to the injector to be regulated and remain constant.

Then, a stand in which to mount the injector, above a graduated cylinder, and the associated plumbing could easily be fabricated. All you need is a 12-volt source to operate the injector which can be garnered from a battery setup or an inexpensive 12-volt DC power supply. If you really wanted to get fancy, you could set up a timer switch to activate the injector for exactly six seconds at a time. Once you measure the output of the injector during those six seconds, you would have a solid base in which to calculate injector flow.

The test rig also doubles as a wasp nest eradicator. Although, we strongly recommend against this particular form of party trick.

Even going the simple, inexpensive route illustrated in the video, you can still glean quite a bit of information from testing your injectors – like spray pattern and whether an injector is clogged or leaky – as well as having the ability to clean and flush your injectors on your home workbench. Even though we live in a technologically-advanced age, it doesn’t mean the DIY spirit is dead, in fact, it is alive and well.

About the author

Greg Acosta

Greg has spent over a decade in automotive publishing as Senior Editor of Race Pages magazine. In his free time, he is a firearms instructor and volunteer in the police armory.
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