Danger | Risk of explosion caused by fuel igniting, risk of poisoning caused by inhaling and swallowing fuel as well as risk of injury to eyes and skin caused by contactwith fuel. | No fires, sparks, open flames or smoking. Pour fuels into suitable and appropriately marked containers only. | |
Warning | Risk of accident from vehicle starting off by itself when engine running. Risk of injury (bruises and burns) resulting from working on the engine while it is being started or when it is running. | Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts. | |
Note on calculation of tightening torque when using insertion or socket tools with various effective lengths | |||
Notes on possible sources of fault in the low-pressure fuel circuit | |||
| Check | ||
1 | Check all fuel lines, connections and components of the fuel system for damage and leaktightness. | Visual inspection. | |
If leakage is present, | |||
| |||
Seal respective connection and tighten down threaded connection using the prescribed tightening torque. | |||
If damage is present: | |||
| |||
Replace respective components. | |||
2 | Clean fouled components of the fuel system on the outside. | ||
3 | Open cap of fuel tank. | ||
4 | Dewater fuel prefilter with a heated water separator and check filter element of the fuel prefilter for soiling. | Only for fuel prefilter (with heated water separator). | |
If severe contamination is present, | |||
| |||
Replace filter element of the fuel prefilter. | |||
| |||
5 | Check fuel pre-filter insert for soiling and clean if necessary. | ||
| |||
If severe contamination is present, | |||
| |||
Replace fuel prefilter element. | |||
6 | Check fuel filter element for soiling. | If severe contamination is present, | |
| |||
Replace fuel filter. | |||
| |||
7 | Start engine and warm up to operating temperature. | See information from body manufacturer. | |
8 | Switch off ignition. | ||
9 | Check fuel low-pressure circuit for leaks. | Only if the engine starts badly. | |
Banjo bolt, fuel line (flame starting system) to banjo bolt and valve | |||
Nut, feed line and return line to fuel filter | |||
Pressure drop in low-pressure fuel circuit | |||
Test pressure for fuel low-pressure circuit | |||
Test period for fuel low-pressure circuit | |||
High-pressure hose | |||
Tester | |||
Adaptation parts | |||
10 | Measure fuel pressure downstream of the fuel filter. | Only if engine performance is poor. | |
Banjo bolt, fuel line (flame starting system) to banjo bolt and valve | |||
Fuel pressure downstream of fuel filter | |||
High-pressure hose | |||
Adaptation parts | |||
Tester | |||
If the fuel pressure is in the tolerance range, | |||
| |||
do not perform further tests on the fuel low-pressure circuit. | |||
If the fuel pressure is too high, | |||
| |||
Measure fuel return quantity at the fuel tank. | |||
Fuel return quantity at fuel tank | |||
If the fuel pressure is too low, | |||
| |||
Measure fuel intake pressure upstream of fuel pump. | |||
Nut, feed line and return line to fuel filter | |||
Fuel suction pressure upstream of fuel pump at filter supply | |||
Tester | |||
Adaptation parts | |||
11 | Close cap of fuel tank. | ||
12 | Perform engine test run and bleed fuel system. | See information from body manufacturer. | |
13 | Switch off engine. |
123 589 04 21 18
High-pressure hose
541 589 00 91 00
Adaptation parts
617 589 04 21 00
Tester
541 589 02 21 00
Tester
Referenced documents
- ah0000p001501cw Note on calculation of tightening torque when using insertion or socket tools with various effective lengths
- ah0715n100002f Notes on possible sources of fault in the low-pressure fuel circuit
- ap4720g0730dd Clean filter element of fuel prefilter
- ap4720g0780dd Replace fuel filter
- ap4720g0783dd Fuel prefilter with water separator - replacing filter element
- ar0715g200002dd Measure fuel pressure downstream of fuel filter
- ar0715g200003dd Measure fuel return quantity at the fuel tank
- ar0715g200004dd Check low-pressure fuel circuit for signs of leaks
- ar0715g200005dd Measure fuel intake pressure upstream of fuel pump
- as0000z000501a Risk of accident from vehicle starting off by itself when engine running. Risk of injury (bruises and burns) resulting from working on the engine while it is being started or when it is running.
- as4700z000101a Risk of explosion caused by fuel igniting, risk of poisoning caused by inhaling and swallowing fuel as well as risk of injury to eyes and skin caused by contactwith fuel.