Engine
SHOP MANUAL
Ch 1 page 213
H2 – Checking the return fuel pressure
1. Connect pressure gauge 99 362 to the test connection on the return fuel manifold and open the test connection.
2. Start the engine. Read the pressure with the engine idling. The pressure should be below 0.8 bar. If the pressure
exceeds 0.8 bar the overflow valve on the return fuel manifold should be cleaned and visually inspected. Start again
from step 1.
3. Switch off the engine, remove the pressure gauge and close the test connection.
H3 – Checking the safety valve
1. Start and run the engine at idling speed for 15 seconds and then switch off with the key. Check whether the return
line from the safety valve to the return fuel manifold is hot.
2. If it is hot this is because the safety valve was open when the engine was last run. The most probable cause of
this is that the fuel inlet metering valve is stuck in the open position. Continue troubleshooting by renewing the fuel
inlet metering valve.
3. If the return line is not hot, start the engine and run the check “Leak testing the safety valve” with SDP3 without
removing the return line.
4. If the return line becomes hot during the check “Leak testing the safety valve” the safety valve is faulty. Continue
troubleshooting by renewing it.
5. If the return line does not become hot but the accumulator pressure does not reach 2,400 bar, the safety valve is
probably working. Cancel the check and continue troubleshooting the fuel system.
6. If the return line does not become hot and the accumulator pressure reaches 2,400 bar, remove the return line
and run the check “Leak testing the safety valve” again. If the safety valve leaks more than 3 drops a minute it is
faulty and needs to be renewed.
7. Refit the engine pipes. Torque tighten.
When the overow valve is removed air will be introduced, against the
direction of ow. It will take some time for the system to bleed itself. Dur-
ing this time the measurement is not reliable. Leave the engine idling for a
while before repeating the test. If the pressure still exceeds 0.8 bar, there is
internal leakage in an injector.
NOTE
For safety reasons it is important that the return line is not removed dur-
ing step 3. If the safety valve were to open during the check with the line
removed, hot fuel would spray out with great force.
WARNING
The accumulator may be under high pressure. Reduce the pressure using
SDP3 before starting work. Wear protective goggles
There is a risk of burn injuries when the safety valve is open.
WARNING
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