What is the reason for the actual rail pressure being severely too low?

1 Answers
VanMorgan
07/30/25 7:51am
The reasons for severely low actual rail pressure are either insufficient fuel entering the rail or excessive fuel flowing out of the rail. Common rail diesel engines are sensitive to fuel lines: Common rail diesel engines are very sensitive to air in the fuel lines. If there is air in the fuel lines, it can result in partial or no diesel reaching the engine fuel lines, and it may also trigger fault codes for the rail pressure closed-loop control mode, causing difficulty in starting or failure to start the engine. Rail pressure cannot be established: If there is no air in the fuel lines and the engine still fails to start, the issue may involve fuel line problems. In this case, it is necessary to use diagnostic software for electronically controlled common rail diesel engines to check the actual rail pressure in the common rail pipe when the starter is cranking the engine. If the actual rail pressure is lower than the set rail pressure and this condition persists for a long time, it indicates that rail pressure cannot be established, and the engine cannot start.
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