Table of faults with excessive fuel consumption
Before checking, make sure that the serial tires are installed and the wheels rotate freely (check brakes and bearings), the running-in is complete (about 5000 km).
| Malfunction | Cause and solution |
| The air filter is dirty | Clean or replace the filter insert |
| Leaks in the fuel system. | Perform a visual inspection of all fuel lines, fuel filter and fuel pump. |
| The fuel return line is clogged. | Blow out the outlet line from the fuel pump to the fuel tank. |
| Idle speed or maximum speed is too high. | Check and adjust idle speed and top speed. |
| The injectors are faulty. | The injectors are leaking, dirty, the injector needles are broken. Incorrect injection pressure. Loose thermal insulation under the injectors. |
| Incorrect feed start adjustment. | Check the feed start setting. |
| Faulty fuel pump | Install a new pump for testing. |
| Mechanical engine faults. | Incorrect valve clearance, leaky valves, worn cylinders and pistons, leaky cylinder head gasket. Narrowing in the exhaust system. Check valve clearance and compression. |
In addition to those listed, the following causes of malfunctions are important for turbodiesel:
| Leaky turbocharger components. | Loose air hose between supercharger and suction pipe or between suction pipe and fuel pump. - Leaks between suction pipe and cylinder head. Loose suction pipe flanges. Weak relief valve clamp or loose 0 - ring. Leaks between exhaust outlet and cylinder head or supercharger |
| The supercharger is faulty. | Check boost pressure (in the workshop). If it is too high and the control line to the control valve is good, replace the supercharger because the supercharger control valve is bad. If the boost pressure is too low, the relief valve is bad. |
| The relief valve is faulty. | Remove and plug the hose from the relief valve. Repeat the boost pressure check. The pressure should drop by about 0.05 bar. If the pressure does not drop or increases, replace the fuel pump. |
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