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Introduction
This Special Instruction is intended to give information for troubleshooting C7 and C9 HEUI engine fuel systems. Read all of the instruction before performing any of the procedures listed in this instruction.Low Pressure Fuel System Requirements
Increasing fuel supply pressure and effectively removing water and abrasive particles has demonstrated injector durability increases from 200 percent to as high as 1,000 percent in severe applications. More aggressive filtration and monitoring is required to maximize fuel injector life and meet increasing reliability and durability expectations. Conversely, reliability and durability goals cannot be achieved without the following improved filtration and monitoring features.Fuel Tank Drain
Fuel tank drains are used to drain water and sediment from the fuel tank daily. The drain must be located on the lowest part of the fuel tank where the containments collect.Note: Daily draining of water and sediment from the fuel tank has been a standard maintenance requirement for decades.Advanced Tank Breather Filter
Preventing short fuel system life by keeping dust from entering the fuel tank.Water Separators
Water separators are required to remove large quantities of latent water from the fuel.Primary Fuel Filters
Primary fuel filters are required to remove large abrasives from the fuel supply and prevent premature clogging of the 4-micron secondary filters from excessive debris.Secondary Fuel Filters
Series filtration more than doubles wear life over single filtration.Electronic Unit Injectors (EUI)
An adequate fuel supply pressure is essential to prevent cavitation of internal injector components due to incomplete fuel fill.Major Factors Which Negatively Affect Fuel System Wear
Abrasive Contaminants
Increased injection pressure acting on the same level of abrasive contaminants in the fuel results in accelerated injector abrasive wear. This abrasive wear cannot be eliminated by using improved materials or processes. Abrasive wear only can be reduced by removing abrasives from the fuel. Solution
Single or series High Efficiency fuel filters and/or bulk fuel filter/water coalescer.Water in Fuel
An excessive amount of latent water in the fuel is a key cause of injector failure. Water has inadequate film strength to prevent metal-to-metal contact between the plunger and barrel, resulting in plunger scuffing or seizure. Water can be effectively by the use and regular maintenance of a water separator or bulk fuel filter/water coalescer. Removal of excess latent water is essential to prevent scuffing with the upcoming injection pressure increases and subsequent hydraulic loading of internal injector parts.Solution
Proper maintenance of fuel tank drains, water separators and/or use of a bulk fuel filter/water coalescer.Excessive Fuel Temperature
Increasing fuel temperatures reduces fuel viscosity and resultant fuel film strength. Reduced film strength increases the probability of injector plunger and barrel scuffing or seizure. Limiting the maximum fuel temperature will become even more critical with the increase of use if low sulfur fuel which has a lower film strength and common rail fuel systems which run elevated fuel temperatures. Fuel temperatures also play in diesel and biodiesel fuel degradation.Solution
Properly maintain fuel filters and fuel coolers where needed. Ensure proper consideration for materials used in fuel coolers as zinc, copper, lead, and tin can have adverse effects on fuel degradation.Customer Maintenance Practices
Fuel system performance, sophistication, and complexity continue to increase at a rapid pace. It is more important than ever for the user to maintain fuel filters in order to prevent filter restriction and the problems caused by low fuel pressure. It is also important to use quality Advanced Efficiency filters in order to trap and hold microscopic abrasive debris, which causes accelerated wear in modern fuel systems.C7 and C9 HEUI Fuel System Diagram
Note: The following illustration identifies components that may be included in many different arrangements. Refer to the Service Information System (SIS) for the correct components for the engine that is being serviced.
Illustration 1 g02385638
(1) Fuel injection pump (2) To engine (3) Oil filter (4) Engine oil pump (5) Injection actuation pressure sensor (6) Fuel injectors (7) Fuel supply passage (8) 2 mi