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How to Bleed the Fuel Injection System of a Diesel Engine

Website design By BotEap.comThere are certain rules of thumb when it comes to learning how to bleed a diesel engine. There are dozens of different diesel fuel injection systems in operation, but the same principle applies to all of them. The fundamental principle is to remove air from the fuel system. Take a look at this scenario below.

Website design By BotEap.comSo you’re driving down the highway and suddenly your diesel engine starts to detonate, loses power and expels a large amount of white smoke. It eventually dies and after a few cranks you decide to check it out more. You realize that the fuel tank is empty. The last time you checked the fuel gauge, it read half a tank, and you find that it still reads half a tank after driving 100 miles. A faulty fuel gauge sender (located in the tank) is not an uncommon problem that causes more trouble with an engine shutdown condition.

Website design By BotEap.comSo now that you’ve determined the cause of the problem, it’s time to fill the tank with diesel and bleed the fuel system. Generally speaking, diesel engines require a high pressure atomized spray that becomes a combustible mixture when combined with high compression. Compressed air is heated enough in the combustion chamber to ignite the mixture and provide the high-power thrust that diesel engines are known for.

Website design By BotEap.comStep One – How to Bleed a Diesel Engine

Website design By BotEap.comThe first thing to do is fill the tank and fill the primary fuel filter (closest to the fuel tank) with clean diesel fuel. This filter relies on vacuum or suction from the fuel transfer pump to keep it primed and move to the secondary fuel filter. Diesel fuel transfer pumps are mechanically driven by the camshaft or driven by an electric motor. If you have many blessings, you may even have a hand priming pump built into the system.

Website design By BotEap.comStep Two – Removing Air from the Diesel Fuel Injection System

Website design By BotEap.comAny way you look at it, the main purpose is to remove air from the fuel injection system. Loosening fuel lines is common practice for older diesel engines. Loosen the fuel line fittings before the injection pump and then run the hand priming pump until you see no more bubbles coming out of the loose fuel lines. This will ensure there is fuel at the injection pump.

Website design By BotEap.comStep Three – Bleeding a Mechanical Bosch Diesel Fuel Injection System

Website design By BotEap.comAs an example, the Bosch fuel injection pump found on Cummins diesels has a bleeder plug on the front right hand side of the pump body and can be loosened first while pumping the hand primer found on the right hand side of the pump body. of the block driver. The mechanical fuel injection system on these engines has exposed fuel lines for easy access. Loosen all injection lines on the head. Starting the engine will speed up the air removal process. When the fuel system begins to pick up fuel, the engine will try to start and will stumble. At this point, tighten the fuel lines and keep cranking the engine, you’ll have firepower before you know it.

Website design By BotEap.comBleeding an electronic diesel fuel injection system

Website design By BotEap.comNewer diesel engines went to an electric fuel transfer pump. As soon as you turn on the ignition key, the pump kicks in and automatically primes the fuel system. Using the Cummins ISC diesel engine as an example, to prime you must first fill the primary filter with clean diesel fuel and install the secondary fuel filter dry. Once the ignition key is on the fuel transfer pump, it will prime the secondary filter with clean filtered fuel from the primary fuel filter.

Website design By BotEap.comOnce you know how to bleed a diesel engine and check it out a few times, you’ll see the importance of getting the air out of the lines. The air is compressed and does not allow any movement of diesel fuel which resists the build-up of high pressures that diesel fuel injection systems require to start and run the engine.

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