Water or foreign substance is mixed.

Solvent or chemical substance is mixed.

Gasoline or kerosene is mixed.

Corrosion, wear, blocking, sticking (in the fuel system)

Carbon deposit in the injector nozzle and a combustion chamber by incomplete combustion.

Excessive black smoke by incomplete combustion.

Catalytic system is damaged by incomplete combustion, especially CPF could be damaged.

Solidification of paraffin wax added in the diesel for viscosity and lubrication. (Hard starting in the winter)

IG KEY "OFF", ENGINE "OFF"

Remove air cleaner assembly and MAFS.

Disconnect the fuel input quick-connector and the output connector.

Disconnect the thermostat connector, the heater connector and water sensor connector.

- Make sure of fuel leak after disconnecting fuel hose quick-connector and an inrush of foreign substances.

Unscrew the three fuel filter bracket mounting nuts and Remove the fuel filter assembly.

Prepare a clean beaker. (for receiving diesel fuel)

Remove the water sensor.

Inspect the diesel fuel (foreign or metallic substances, water etc...from receiving diesel fuel in the beaker).

- Metallic substances would be found by magnetic.

Inspect the diesel fuel color (too transparent or too red color is not good) in the beaker.

- Diesel fuel color would be different by oil companies.