Fuel System Cleaning Fuel System
Fungi and other microorganisms can survive and multiply in diesel fuel if water ispresent. The fungi can be present in any part of the fuel handling system. These fungigrow into long strings and will form into large globules. The growths appear slimyand are usually black, green, or brown. The fungi may grow anywhere in the fuel butare most plentiful where diesel fuel and water meet. As the fuel is agitated, whenservice station tanksare being filled, fungi are distributed throughout the tank and may be pumped intoa vehicle.
Fungi use the fuel as their main energy supply and need only trace amounts of waterand minerals. As they grow and multiply, they change fuel into water, sludge, acids,and products of metabolism. The most common symptom is fuel filter plugging; however,various metal components including the fuel sending unit, pipes, fuel injectors, andinjection pump can corrode.
Warning:Avoid physical contact with the biocides in order to avoidpersonal injury.
If fungi have caused fuel system contamination, use a diesel fuel biocide to sterilizethe fuel system. Do not exceed the dosage recommended on the label. Discontinue theuse of a biocide when towing a trailer. It is permissible to have biocide in the fuelwhen starting to tow, but do not add any biocide while towing.
Steam cleaning may be necessary if most of the fungus growth cannot be removed withbiocides.
The presence of water or gasoline in diesel fuel may also cause injection pump andnozzle damage.
This procedure checks for the presence of water and gasoline in diesel fuel that maycause injection pump and nozzle damage.
Remove and inspect the fuel filter element.If water, gasoline or fungi/bacteria are not present, end the inspection.If water or fungi/bacteria are present, proceed to Cleaning Water from the Fuel System.If gasoline is present, proceed to Cleaning Gasoline from the Fuel System.Cleaning Water from the Fuel SystemDisconnect the negative battery. Refer toBattery Negative Cable Disconnection and Connection.Remove the fuel sender assembly. Refer toFuel Tank Fuel Pump Module Replacement.Inspect the fuel tank and the fuel sender for rust, fungi or bacteria. If there isrust, replace the rusted components.Clean the inside of the fuel tank and the fuel sender with hot water.Use compressed air in order to dry the fuel tank and the fuel sender.Disconnect the ends of the following lines:The fuel filter inlet line (both ends)The transfer pump pressure line and suction line (if applicable)The fuel filter outlet line (both ends)The fuel filter drainThe fuel return line (both ends)Inspect each of the pipes and lines.Replace any rusted pipes.Clean the inside of the fuel filter housing.Dry the fuel filter housing with compressed air.Dry the inside of each line with low pressure air.Disconnect the crankshaft position sensor.Install a new fuel filter. Refer toFuel Filter Replacement.Install the fuel sender assembly Refer to .Fuel Tank Fuel Pump Module Replacement.Add clean diesel fuel to the primary tank until the tank is ? full.Reconnect the following lines:The fuel filter inlet lineThe fuel filter outlet lineThe transfer pump pressure and suction (both ends) linesThe fuel return line (tank end)Connect the fuel filter drain to a line that flows into a clean metal container.Connect the batteries.Operate the fuel system hand primer at the fuel filter until clean fuel flows fromthe fuel filter drain into a metal container.Close the fuel filter drain and remove the bleeder hose.Install a hose on the fuel return line near the glow plug relay, and insert otherend into a 7.6-liters (2-gallon) metal container.Crank the engine for 15-second time intervals, with 1-minute cool-down periods. Continueuntil 3.8-liters (1-gallon) of fuel has passed into the container.Connect the fuel return line.Reconnect the crankshaft position sensor.Start and run the engine.Stop the engine.Clean any fuel spillage from the engine.Fill the fuel tank and add a biocide, if needed.Cleaning Gasoline from the Fuel SystemDrain the fuel tank.Fill the fuel tank to ?-full.Loosen the fuel filter drain and connect the filter to a hose that flows into a metalcontainer.Operate the fuel system hand primer at the fuel filter until clean fuel flows fromthe fuel filter drain into the metal container.Hand tighten the fuel filter drain and disconnect the hose.Install a hose on the fuel return line near the glow plug relay, and insert the otherend into a 7.6-liters (2-gallon) metal container.Crank the engine for 30-second time intervals, with 1-minute cool-down periods. Continueuntil 3.8-liters (1-gallon) of fuel has passed into the container.Reconnect the fuel return line.Attempt to start and run the engine for 15-minutes. If the engine does not start,operate the hand primer for 30-strokes, or until firm.Stop the engine.Clean any fuel spillage from the engine.Clear the engine of any diagnostic trouble codes (DTCs).