What are the consequences of a clogged diesel engine return pipe?

[VanEllie]

Consequences of a clogged fuel return pipe in diesel and gasoline engines: In severe cases, it can affect engine startup because it relies on compression ignition. If the air-fuel ratio is not properly controlled during fuel injection, it may cause issues. However, generally, the engine can still start, though it may emit black smoke. When the fuel pump is operating, a clogged return pipe will increase the fuel pressure in the pipe between the fuel pump and the carburetor. Below is additional information: Fuel transfer pump: By design, the fuel transfer pump cannot deliver a precisely measured amount of fuel; it typically supplies more than the injection pump requires. Additionally, despite the precision manufacturing of the fuel injector needle valve assembly, there are still minute gaps to ensure proper fuel injection. During operation, fuel leakage is inevitable between the needle valve and its seat, as well as between the upper surface of the needle valve body and the lower surface of the injector body.