This communication letter purpose is designed to provide guideline regarding the procedures to be adopted when it has been found out that the injection system is presenting irregular operation.
Problems:
Idle speed oscillation.
Excessive smoke emission.
Difficulties in the start-up.
Possible reasons:
Main fuel filter (3) and prefilter (5) with water separator with excessive restrictions (saturated).
Damaged electric fuel pump (4).
Pressure under the established limit in the low pressure line, between the main filter and the injection pump.
Non-reliable quality fuel or non-approved filtering elements can cause damages in the injection system components and the above mentioned symptoms.
Drain the water accumulated in the prefilter (5) with fuel/water separator at least once a week.
LO 812 vehicles |
3 | Main filter |
4 | Electric fuel pump |
5 | Fuel prefilter |
B07.00-0047-02
LN 710 vehicles |
3 | Main filter |
4 | Electric fuel pump |
5 | Fuel prefilter |
B07.00-0048-05
B07.00-0049-01
A | Calibrated hole at the fuel return outlet: Ø 2,8 mm (LO 812) and Ø 3,2 mm (LN 710) | |||
1 | Injection pump | |||
2 | Manometer | |||
3 | Main filter | |||
4 | Electric fuel pump | |||
5 | Fuel prefilter | |||
6 | Fuel tank | |||
B07.00-0050-01
B07.00-0051-09
Electric fuel pump wiring diagram |
B145 | Engine temperature switch | K127 | Advance valve auxiliary relay | |
D9 | Current return blocking diode | K129 | Auxiliary relay of the advance valve temperature cutoff | |
K37 | D+ auxiliary relay | M19 | Electric fuel pump | |
K108 | Electric fuel pump auxiliary relay | V59 | Magnetic debit valve | |
K126 | Start-up timer relay | V60 | Magnetic advance valve |
Procedures | |||
1 | Install the manometer (2) between the injection pump (1) and the main filter (3) | The manometer (2) must be installed as close as possible to the injection pump. | |
2 | Check the fuel pressure in the low pressure line | If the measurement value is not the desired one, correct the cause. | |
Examples of causes: Fuel main filter(3) and prefilter (5) excessively clogged (saturated), damaged electric pump (4). | |||
Fuel pressure in the low line | |||
3 | Check the operation of the electric pump (4) | If eventually, a divergence occurs, check: the electric connectors fastening or other probable electric causes (see wiring diagram). | |
4 | If the irregularity persists in the injection system, carry out the procedure 5 | ||
5 | Carry out the analysis of the injection pump and injection nozzles in a Bosch authorized workshop | Request an analysis report and card with the values found out in the analysis. If irregularities have been found out, carry out the necessary correction, request the description/report from the Bosch workshop and install the components in the engine. |