Equipment World Digital Magazine
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EquipmentWorld.com | August 2015 71 ounces of fuel per firing stroke, per cylinder at full load. Therefore, the most fuel you would get out of a single fuel line was approximately 10 ounces of fuel at minimal pres- sure after a minute. "With a common rail engine, doing the same thing would generate al- most one gallon of fuel at significant atomization," says Serra. "The velocity of the fuel within a few inches of the leak is high enough to penetrate the skin or gloves," he says. DIAGNOSTICS Some of today's engines can have hundreds of different fault codes for various conditions and symp- toms, but fault codes don't always solve a problem. "Even with all these fault codes, diagnosis still requires a well-trained technician who uses a systematic approach to diagnosing an engine system," says Serra. "There is no replacement for experience and an understanding of cause and effect on the engine. For example, a misfire fault code can be caused by not only a defec- tive injector, but by a faulty EGR system, valve adjustment or wiring harness system." The hardest problems for techni- cians to diagnose are the no-fault- code related complaints, Serra says. Unless they understand how the whole system is supposed to behave, what normal data looks like and how to approach diagno- sis, they will be lost, says Serra. "With the older mechanically injected engines, 95 percent of the fuel system was contained between the injection pump and the injec- tors, so diagnosis was fairly easy," says Serra. "On a common rail engine, the fuel pump and injec- tors are only 25 percent of the fuel system. "I have seen cases where a technician has spent weeks on a modern engine by not following the diagnostic process, replacing many expensive components only to find out he missed a simple fault such as a plugged fuel filter." DURABILITY According to Fier, a recent tear- down and inspection of a Cum- mins Tier 4 engine showed that a 20,000 hour life-to-overhaul could be expected on its HPCR injectors. The caveat is that it depends on duty cycle, application, good filter maintenance and clean fuel. "These engines do not require a scheduled change of fuel injec- tors at mid-life and are expected to achieve the same life as the engine," Fier says. "Perhaps more important than life in hours is the total number of injections over the life of the HPCR system, with 1 billion injections being a typical number." Ready whenever and wherever you are. Equipment World Magazine makes it easy to keep up-to-date while you are on the go. Get the latest news in the construction industry, along with insight from our award-winning editorial team, through our mobile version of EquipmentWorld.com. Test it out for yourself and subscribe at EquipmentWorld.com.