How To Bleed Your Engine

Often, engine starting problems, are caused by small amounts of air in the fuel. A common cause of this problem is when you run out of fuel, if this happens you will need to know how to “bleed” your engine, which rids the fuel lines of air, so the engine can start.

If you are an owner of a diesel engine bleeding is an essential skill. If you are familiar with the manufacturer’s recommended procedure for bleeding your engine, follow it, but generally, the procedure is as follows.

When bleeding the fuel line, especially when the starter motor is used to operate the fuel lift pump, wrap rags around all venting units to collect excess diesel fuel that splashes out.


Open the fuel supply valve, (usually located near the fuel tank this is the on/off switch) and use the manual fuel pump (found on most diesels at the side of the engine).

(The process is similar to bleeding your central heating radiators)


Expel air from the filter, then the pump as in the last paragraph. Make sure that all the injectors are tight in their bases and all of the fuel line connections at the top of the injectors are loose, this will allow the fuel and air to spurt out of them when the starter motor is engaged.

Have the correct size spanner in hand, ready to tighten the fuel line connections when the fuel runs clear without air bubbles.

Your engine may start before you all injectors have been tighten. This is completely normal so don’t panic. Just release your pressure on the starter button or key and let the engine run while you continue to monitor the fuel flow from the remaining un-cleared injectors.

As an alternative to using the starter motor you can also put the decompression lever in its decompressed position and hand crank the engine to move fuel to the injectors. When all injectors are cleared of air and their fuel connections tightened down, you are ready to start your engine.