Using the vas tester, perform the guided function vent fuel system. Advanced modelbased diagnosis of internal combustion. Stft and ltft values will be displayed by number e. If all diesel engines had nearly identical fuel system trouble, diagnosis and. Fuel pressure should be a constant 10 15 psi on a tbi fuel injection system and is typically around.
This is a unique fuel system, in that is does not have a fuel. Often this is the retailer, but it could also be the consumer. Now that we have an understanding of the fuel injection fuel control system, lets put it to work in repairing vehicles. To monitor the residual fuel pressure, connect a fuel pressure gauge to the vehicle. If a faulty fuel injector is found, replace the appropriate fuel injector. If the engine runs but displays driveability symptoms that you suspect are fuel. Baselining the fuel trim data is a simple fourstep diagnostic process. Fuel system checks fuel pressure is critical to the operation of a fuel injection system.
The two leading causes of electric fuel pump failure are. They can range from having difficulty in getting the engine to fire upon starting, poor idle where the revs fluctuate or a rougher performance at speed. Use these diagnostic charts to quickly and accurately determine the exact cause of electric fuel system malfunction. Always check to insure that you have the proper fuel pressure.
Pdf in order to solve the problem that the diesel engine pt fuel system is unable to field maintain, developed a portable signal acquisition and. General motors llc fuel system control module fscm. But dont immediately assume that the pump is the problem. Purposely or knowingly defeating or disabling any part or the fuel and emission system may be in violation of the antitampering. Check the oil level, lb7 engines have the injectors under the valve cover and are very susceptible to dilution. Comparison of fuel trim data for v type engines when the system utilises fuel system monitoring is a good way to see if a problem exists on one bank or is affecting both banks. Fuel system diagnosis correctly diagnosing a low pressure, low volume or nofuel problem a lack of fuel to the engine may signal a failed fuel pump. Diesel engine performance diagnosis intro 3 june, 2006 course requirements each technician attending this course will be required to pass a combination of handson and written evaluations. The intank fuel pump will remain on as long as the engine is cranking or running and the pcm is receiving reference pulses. Its also possible to make up a simple lead with a push button switch box to do exactly the same job. Connect an obd ii generic scan tool, preferably with recording capabilities. Read and understand the operators manual before using the fuel system cleaner.
To test the fuel pump, remove relay 80 fuel pump relay from its socket. Test the fuel injector return flow, refer to fuel injector diagnosis. Since the fuel injection system is all about the air, it will be necessary to calculate the volumetric efficiency ve of the engine see mark warrens june 2003 driveability corner for a concise explanation of ve. Pdf injection diagnosis through commonrail pressure. All information, illustrations and specifications contained in this manual are based on the latest product information available at the time of publication approval. Remember, fuel trim data contained in either scanner freeze frame mode, or, that. The term open loop means that the pcm is not using the o2 sensor signal voltage to influence the air fuel mixture. Diagnostic function o manufacturers have to implant faults and verify detection on. The fuel pump check valve, fuel pressure regulator and fuel injectors hold residual pressure within the system. Injection diagnosis through commonrail pressure measurement article pdf available in proceedings of the institution of mechanical engineers. The complete learning package includes a multimedia cd rom with illustrated power. Ford electronic returnless fuel system diagnosis part 1. How to test a fuel pump on a 2000 ford taurus electronic returnless fuel system.
Other fuel system components wiring repairs make a note of these previous repairs as these may affect the outcome of the diagnosis. Restricted fuel filters some 20032005 excursion, 20032007 fsuperand or fuel lines, or an inoperative fuel pump duty and 20042008 eseries vehicles equippedcan create a low or negative fuel supply pressure. Fuel pressure should be a constant 10 15 psi on a tbi fuel injection system and is typically around 12 psi. Perform fuel system bleeding diesel engine, in order to get the engine started. The pump remains on as long as the engine is cranking or running and the vcm is receiving reference pulses. Misdiagnosis vehicle related electrical wiring or connector issues contaminated vehicle fuel systems misdiagnosis misdiagnosis is the leading cause of fuel pump returns. Once your fuel supply system tests ok, then the next step in a fuel system diagnosis is how fuel is distributed to the cylinders. See my photo on the 1600i website for further details under electronics, 1600i engine bay. Operation, diagnosis,and service 673 figure 297 the vacuummodulated pressure regulator controls system fuel pressure with a springloaded diaphragm. Follow the gm fuel system diagnosis in the service manual. Then start and run the vehicle for a short period of time. If the trouble continues even after the trouble has been fixed with scan tool, must perform the fuel pressure test. If there are no reference pulses, the pcm will turn the intank fuel. The fuel system contains high pressure fuel up to 25,000 psi.
Many owners can brag about 2 and 300000mi service with very few if any issues. It emphasizes diagnosis and troubleshooting, and features tech tips and diagnostic stories throughout. Fuel system diagnosis system description when you turn on the ignition switch, the powertrain control module pcm turns on the intank fuel pump. The right is reserved to make changes at any time without notice.
When using chemicals always refer to the msds sheets and manufacturers instructions for the proper procedure to handle emergency medical treatment, cleanup, handling, and storage requirements. Fuel system diagnosis correctly diagnosing a low pressure. Fuel system diagnosis correctly diagnosing a low pressure, low volume or no fuel problem a lack of fuel to the engine may signal a failed fuel pump. Fuel system diagnosis circuit description when you turn on the ignition switch, the powertrain control module pcm energizes the fuel pump relay which powers the fuel pump on. Service the highpressure oil system and fuel injectors by. To eliminate the chance of fire or personal injury, the fuel system pressure must be relieved before servicing any fuel system component.
This means that various parts of the system were selected and fitted by the boat builder, the engine maker and the engine installer. If the test plan is unavailable through guided functions, switch to self diagnosis engine electronicsbasic settings35 and perform the basic settings 3 times consecutively. Fuel system diagnosis fuel system description fuel is drawn by the supply pump through a prefilter screen in the tank and to the engine through the fuel supply lines. The term closed loop means that the o2 sensor signal voltage is directly influencing the air fuel mixture. Prime the fuel system with the hand primer until 10 psi is indicated on the gauge. The intank fuel pump remains on as long as the engine is cranking or running and the pcm receives reference pulses. Common fuel systemfuel related problems and how to fix. Fuel pump control state normal or frp rationality control.
Below schematic diagram shows the specifications of pressure, flow mass and temperature in fuel system. Pdf fuel injection system fault diagnosis based on cylinder. Lpg fuel system trouble diagnosis lpg fuel system trouble diagnosis condition cause action fuel leakage looseness of piping connection tighten operating malfunction of vaporizer repair, adjust or replace poor connection or some foreign object is caught in between plunger rubber seat and valve seat of solenoid valve clean, rub or replace. Here the pressure gauge can be used again, this time in the supply line as close as possible to the individual carburetor or. Fuel injectors if your engines fuel system develops a problem with even one of its injectors the symptoms should be immediately noticeable.
Common rail type fuel injection system development history and the. The fuel passes through the base plate of the fuel injector control module ficm to cool the module. But as with any mechanical thing some do have their problems and i wont try to cover all of them right now but i want to give a few pointers you should. Pdf this work aims at monitoring diesel engine fuel injection system by analyzing the cylinder head variations. Pdf diesel engine pt pump fault diagnosis based on the. Take a fuel sample from the water separator fuel filter by referring to the water separator draining procedure. Step one do all carburetors or injectors get an equal chance at the fuel supplied. Fuel system diagnosis gasoline is volatile and vapors will settle in low areas, so work in a wellventilated space away from sparks or open flame such as a pilot light. Nearly 75% of all aftermarket fuel pump failures are caused by. Fuel system diagnosis circuit description when the ignition switch is turned on, the powertrain control module pcm will turn on the intank fuel pump. Fuel status bank 2 this parameter displays the status of the fuel system whether it is in closed loop or open loop. High pressure fuel entering your bloodstream may result in amputation or loss of life. If less than 3bar 43psi, refer to fuel return system diagnosis for further diagnosis. The fuel system contains high pressure fuel up to 26,000 psi.
The fuel filter housing is on the suction side there is not a supply pump from the factory and are prone to suck air. The pump remains on as long as the engine is cranking or running and the pcm receives reference pulses. Automotive fuel and emissions control systems 2nd edition. A diesel engine uses a fuel system with a precision injection. All emission related fault codes must be consistent with those described in section 6. There is no lift pump in the fuel tanks or on the frame. Onboard diagnostics obd program overview california air resources board. Using a scan tool, perform high pressure fuel system test to check system.
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