• Why You Should Not Ignore Your Fuel Injectors

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    Scream And Fly
    Published on 07-13-2024 09:29 AM
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    A Q and A with Blake Pankratz at Canadian Injector Service ▼
    With the boating season in full swing, this article should be required reading for folks that might not be aware of the importance of maintaining your fuel injectors and the penalties on overall engine performance and economy by not doing so.
    InjectorService.com has been a very highly-trusted vendor here for a long time, and Blake's company employs the very latest equipment and techniques to diagnose and service fuel injectors. I have come to know Blake pretty well over the years, and I feel there is no better person to explain the importance and intricacies of maintaining fuel injectors.
    Mercury 2.5-liter fuel injectors during testing.
    How often should injectors be tested/serviced? Is this something that most people overlook?
    This is probably the question I get asked the most often, and it is the most difficult to answer because there are so many variables. In theory and in a perfect world, you should not ever have to clean your injectors if you ran high-grade fuel and were religious with your fuel treatment plan. Unfortunately, that is not the case, and everyone’s situation is different, so here are some scenarios when it is prudent to have the fuel injectors cleaned and tested:


    • Any race applications, especially if alcohol or race fuels are used. These fuels can be really hard on injectors.
    • Purchasing a motor or injectors from an unknown source, especially if they have sat for some time without running.
    • Any time you have a fuel issue, especially a contaminated tank or water in fuel.
    • Any time you have a fuel pump failure, especially with an electric pump.
    • Any time you have an engine failure.
    • Any time you have an air compressor failure on a direct-injected engine.


    As far as regular maintenance, for recreational boaters I suggest every two to three years, dependent on use. If you are very diligent with your maintenance and fuel treatment, those service intervals can be longer.
    Mercury 2.5-liter fuel injector flow testing.
    Most boaters do not feel the need to have their fuel injectors cleaned and tested as long as their engine appears to be running well. Typically, how would the performance of well-used and unserviced fuel injectors compare with fully serviced injectors?
    We see many different scenarios in flow difference. We do get a number of sets that are nearly perfect upon initial testing. But we also get sets that have 25% or more increase in flow after cleaning. I have attached some examples I will explain below as well.

    In more extreme situations, where injectors have not been tested for decades, would the performance penalty be severe?
    Absolutely, as with many maintenance items, performance can suffer and if left long enough catastrophic failure can happen. I like to tell people to use injector cleaning as a tool to prevent failure and as an engine health check, not as a fix once failure has occurred.
    Evinrude E-TEC fuel injector fouling from normal use.
    In practical terms, what are the key benefits of replacing or cleaning and flow-testing old injectors? Would the engine idle better? How about acceleration and top speed? Also, is fuel economy improved with new injectors?
    I’m glad you brought this up because many people feel that they need to replace the injectors when they have a problem. I wouldn’t suggest this as a first resort. Most of the time (95%+) we can clean used injectors to new condition, and even if you do have an injector that needs to be replaced, we know exactly which one. Customers can expect any one of the following: Easier starting, smoother idle, improved fuel economy, more power throughout the RPM range, more top end.

    In addition to performance penalties of using old and neglected injectors, could there be the potential for engine damage such as lean conditions caused by inhibited injector fuel flow?
    Absolutely, I think I have answered this above, but some causes of damage can be due to decreased fuel flow, but also excess fuel flow. Excess fuel flow is especially true with the E-TEC injectors.
    Yamaha HPDI injectors during cleaning procedure.
    Is it important to balance the flow of sets of injectors? How is that accomplished?
    It is very important to have a balanced set of injectors. It would be no different than having a motor with unequal compression or a cylinder with restricted airflow. The fuel into the motor needs to match per cylinder or one cylinder will be doing more (or less) work than the others. The balance of injectors and cylinders is set at the factory. The injectors are precisely machined and set by the manufacturer to deliver the exact amount of fuel and the spray pattern required for each individual application. So new out of the box, an injector set should be balanced. Over time these flow rates vary due to contaminants in the fuel and wear on the injector. After cleaning and flow testing, we should once again see a balanced set of injectors.

    This is precisely why you should stay away from cheap aftermarket injectors claiming to be “drop in” replacements. These injectors are typically sourced from Amazon, eBay, etc. and look very much like the OEM part. The problem is these injectors do not have the equipment required to precisely duplicate the exact flow and spray patterns of the original injector. I haven’t yet come across one of these injectors that I would consider good enough to run. Now that being said, there are manufacturers such as Injector Dynamics for example, that make OEM quality, high flow replacement injectors. However, these are not drop-in replacements and will require a full tune throughout the RPM range.
    Mercury OptiMax air regulator fouling from water debris.
    What are the procedures involved in testing injectors, and could you describe the equipment used?
    Our test equipment is very high quality and regarded as some of the best for its purpose in the world. The equipment is fairly simple at its core. The injectors are mounted to a fuel rail, and either flow into a viewing area for spray pattern, or into cylindrical measurement tubes for flow testing. Multiple tests are performed, which include holding the injectors wide open in a static flow test and dynamic tests that pulse the injectors at various RPM ranges and duty cycles.

    Another test we perform is an inductance test on the electrical coil which measures the magnetic field produced by the coil. This test allows us to observe any changes in the coil as the injector warms up. The inductance test is much more precise than the more-ubiquitous method of resistance testing the injector coil.

    The final process is cleaning the injectors in an ultrasonic bath using chemicals specifically designed for breaking down fuel contaminates without harming the injector. The injectors are pulsed while this cleaning occurs. The injector then gets all filters, O-rings, pintle caps and spacers replaced. Once this process is completed, the injectors are then retested in the same manner.
    Evinrude E-TEC injector flow before and after servicing.
    Many boaters understand the importance of injector performance; however, they may not realize just how central they are to many aspects of overall engine performance. People tend to think that if their engine appears to be running well, the injectors are fine.
    I fully agree. People often just do not understand WHY they should have their injectors tested and cleaned, or even what to expect from us when they do.

    Where I separate myself from the rest is in the level of service and knowledge I can offer a customer. I spend a LOT of time walking through diagnoses of various motors and situations with people to help them come to their final conclusions on whether our service would be a good fit and an overall general diagnosis of their motor. I work on marine and powersports products almost exclusively and would say I have a great knowledge of the specific conditions they operate under and what to look for when chasing a fuel system issue.
    After full cleaning and flow testing, these HPDI injectors are returned to factory-new performance.
    I would say my largest area of expertise and experience would be my work on the OptiMax systems. I frequently get customers calling for information, and even well-experienced marine technicians. When you call my shop, you will be speaking with me on my cell phone every time. There is rarely a call I do not answer, and I’m more than happy to just assist with information.

    InjectorService.com serves customers in all of North America, so if you're not sure of the condition of our fuel injectors, it is likely that there are performance and running quality benefits to be gained from having your fuel system fully serviced. At the very least, it is a smart preventative maintenance measure that could possibly prevent costly damage to your engine.

    Canadian Fuel Injection Service
    143 PTH 12N, Steinbach, MB R5G 1T5, CA
    (204) 326-0390

Frank Mole Transport