Fuel System Bleeding

Cummins diesel engine fuel system bleeding

Controlled venting is provided at the injection pump through the fuel drain manifold. Small amounts of air introduced by changing the filters or injection pump supply line will be vented automatically, if the fuel filter is changed in accordance with the instructions. No manual bleeding of fuel lines is required.

 NOTE: Manual bleeding is required if:  

  • The fuel filter is not filled prior to installation.
  • Injection pump is replaced.
  • High pressure fuel line connections are loosened or lines replaced.  
  • Initial engine start up or start up after an extended period of no engine operation.  
  • Vehicle fuel tank has run empty.

 Bleeding Low Pressure Lines and Fuel Filter(s)  

Venting

Using an 8 mm wrench, open the vent screw.Cummins diesel engine fuel system : low pressure lines

Operate the priming button on the lift pump until the fuel flowing from the fitting is free of air.  Tighten the bleed screw.  Torque Value:   9 N•m [7 ft-lb].

High Pressure Lines Venting :  17 mm, 19 mm wrenchesCummins diesel engine fuel system high pressure lines

WARNING

The pressure of the fuel in the line is sufficient to penetrate the skin and cause serious bodily harm. 

Venting is accomplished by loosening one or more fittings at the injectors and cranking the engine to allow entrapped air to bleed from the lines.

Cummins diesel engine fuel system line fittingsRe-Tighten Line Fittings  Torque Value:   30 N•m [22 ft-lb]

WARNING

Do not bleed a hot engine as this could cause fuel to spill onto a hot exhaust manifold creating a danger of fire.

Start the engine and vent one line at a time until the engine runs smoothly.

CAUTION: When using the starting motor to vent the system, do not engage it for more than 30 seconds at a time: Wait two (2) minutes between engagements.

WARNING

It is necessary to put the engine in the “RUN” position. Because the engine may start, be sure to follow all the safety precautions. Use the normal engine starting procedure.