Leak off pipes

This is one of the quickest and cheapest fixes you can do. The leak off pipes link the injectors to a spill rail, which takes excess fuel back to the injection pump and then back to the tank. They are small braided hoses that can wear over time and can introduce air into the system.

The fuel that runs through them is of a low pressure and it is not always noticeable when these perish, but they can introduce air when the engine is off. This can cause long cranking times when starting, attributed to the diesel draining back to the tank. On a cold start the fuel then has to be drawn up the pipes again to the engine. It’s not always the cause, but is such a cheap and quick fix that it’s worth doing anyway.