Petrol models
The fuel system consists of a rear-mounted fuel tank containing an electric fuel pump, fuel filter, fuel injectors, fuel pressure regulator, air cleaner assembly, throttle body, and fuel supply and return lines running underneath the vehicle and connecting the fuel tank to the fuel line. All models are equipped with an electronic fuel injection system controlled by the ECM (see section Fuel injection system of gasoline engines).
Fuel vapors that accumulate in the tank and fuel lines while the car is parked are collected in an adsorber filled with activated carbon, from where they are then discharged into the intake tract and burned during normal engine operation.
Information about fuel consumption is displayed on the vehicle's instrument panel.
Driving style has a significant impact on fuel consumption. Here are some tips for using the accelerator pedal wisely on fuel-injected vehicles:
- In any weather (even in frost) start driving immediately after starting the engine;
- When stopping the car for more than 40 seconds, turn off the engine;
- Try to always drive in the highest possible gear;
- On long journeys, try to maintain a constant speed. Avoid driving at excessively high speeds. Drive carefully, avoid braking without reason;
- Do not carry excess cargo in your vehicle; if not necessary, remove the roof rack;
- Check your tire inflation pressure regularly - try not to let it drop too low.
Diesel models
The fuel system consists of a fuel tank installed in the rear of the vehicle, equipped with a built-in water separator, a heated fuel filter, a high-pressure fuel pump (HPFP), injectors and fuel lines connecting the system components
The injection pump takes fuel from the tank and passes it through the fuel filter, where foreign particles and moisture are captured. Any excess fuel not used by the engine is used to lubricate the internal components of the pump, after which it is returned back to the fuel tank.
The fuel injection pump is driven by the crankshaft. The pump operating speed is exactly half of the crankshaft speed. The high pressure required to open the injectors and inject fuel into the pre-chambers/directly into the cylinders is achieved by using a radial plunger pump.
The injection pump has electronic control, due to which the engine fully complies with the ever-tightening international requirements for reducing exhaust toxicity. The main elements of the control system are the electronic engine control module (ECM), the injection pump control unit built into the pump assembly and a set of information sensors (see Part Diesel engine fuel injection system).
Four fuel injectors inject atomized fuel into the cylinder pre-chambers. Optimization of the mixture combustion process is ensured by fine calibration of the injectors. The injector needles are lubricated with fuel accumulated in the spring chambers, and unclaimed excess fuel is returned to the high-pressure fuel pump via separate lines.
In order to increase the efficiency of the output, the X15DT engine is equipped with a turbocharger, which provides excess pressure in the intake manifold relative to atmospheric pressure, which allows to increase the mass flow rate of air supplied to the cylinders - the fuel supply also increases proportionally. Installed between the exhaust manifold and the inlet pipe of the exhaust system, the turbocharger, which operates from the exhaust pressure, takes air from the air cleaner, and, if equipped accordingly, passes it through the intermediate cooler heat exchanger mounted on the left side of the radiator of the cooling system (intercooler) and feeds it under pressure into the intake manifold. The task of the intercooler is to cool the air heated during compression in the supercharger and fed into the engine. Since the cooled air has a higher density, reducing its temperature allows for an even higher efficiency increase in the engine.
Excessive pressure build-up in the intake manifold is prevented by using a special relief valve that ensures exhaust gas is diverted from the turbocharger using a pressure-sensitive actuator. The valve is triggered by a command from the ECM. A pressure-sensitive switch-sensor triggers a warning lamp mounted in the instrument cluster to warn the driver that the permissible boost pressure has been exceeded.
The turbocharger is lubricated by engine oil coming from the cylinder block through a special tube - the turbine shaft literally "floats" in oil - the return line oil from the supercharger goes back to the oil pan. The turbocharger is equipped with a built-in safety valve and a vacuum diaphragm, which provide regulation of the boost pressure in the intake manifold. The internal components of the turbocharger rotate at high speed and are very sensitive to the quality of the oil. Foreign particles getting on the rotating turbine blades can have the most serious consequences. In view of the above, before removing the compressor, it is necessary to thoroughly clean its outer surfaces, as well as the surfaces of adjacent units. Place the removed components in a tightly closed container. Immediately seal all openings in the compressor with tape, use only lint-free rags to wipe the parts.
Never start a turbocharged engine with the intake air duct removed - the vacuum at the compressor inlet may increase abruptly, which increases the risk of foreign objects being sucked into the turbine and subsequently ejected at high speed!
The fuel system of diesel engines is extremely reliable. Provided that clean fuel is used and maintenance procedures are performed regularly, it should function properly until the end of the vehicle's service life. At high mileage, the internal components of the fuel injection pump and injectors may wear out and require restoration repairs. Due to the complexity of the design of the components, repairs should be entrusted to car service specialists.
Safety precautions and rules for maintaining cleanliness when working with the fuel system
General rules
Do not approach the work area with an open flame or a lit cigarette. Always keep a fire extinguisher ready.
Fuel vapors are toxic - ensure adequate ventilation of the work area.
The fuel system is under pressure. When opening the system, fuel may escape under pressure - wrap the nipple connectors in a rag before releasing them. Use protective glasses.
When working with diesel engine fuel system components, take special precautions. This statement applies especially to injector maintenance procedures. Remember that the fuel pressure at the injector outlet is about 1100 atmospheres - do not put your hands or other body parts under the stream.
To secure the hose connections, use band and clamp type clamps. After disconnecting the hoses, the clamp clamps should be replaced with band or worm clamps. Fixing the locks of some clamps requires the use of special devices - consult with specialists from the Opel branded service station.
Before disconnecting the nipple connectors, carefully wipe them from the outside to prevent dirt from getting inside the tract.
Place the removed components on a clean lining and wrap them in plastic or paper - avoid using lint-producing rags for wiping and wrapping the components.
If the repair requires time, ensure that all open holes in the fuel system components and assemblies are carefully sealed.
Install only clean parts. Remove spare parts from their packaging only immediately before installation. Do not use parts that have been stored unpackaged (for example, in a toolbox).
Avoid using compressed air when the fuel line is open. If possible, try not to move the vehicle.
Do not use sealants containing silicone. Silicone particles that get into the engine do not burn and may cause damage to the lambda probe.
Safety precautions when removing the fuel tank
Before removing the tank, drain the fuel from it or pump it out using a pump specially designed for this purpose.
The fuel tank is removed from the underside of the vehicle. Before releasing the mounting straps, support the tank from below with a trolley jack - place a wooden block between the tank and the jack head.
An empty tank is explosive and must be cut into pieces before disposal - try to avoid sparking when cutting the tank. The best thing to do is to hand the tank over to a special collection point.
After installing the tank, start the engine and check the tightness of all connections.
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