Chevrolet Full Size Cars 1979-1989

Fuel Filter



The fuel filter is a square assembly located at the back of the engine above the intake manifold. Disconnect the fuel lines in order to remove the filter. When installing, carefully thread and tighten the lines to the new filter. Start the engine and check for leaks.

Water in Fuel

Water is the worst enemy of the diesel fuel injection system. Both the injection pump, which is designed and constructed to extremely close tolerances, and the injectors can be easily damaged if enough water is forced through them along with the fuel. Engine performance will also be drastically affected, and engine damage can occur if significant amounts of water are allowed in the fuel.

Diesel fuel is much more susceptible than gasoline to water contamination. Most diesel engine cars are equipped with an indicator lamp system that turns on an instrument panel lamp if water (1 to 2 1 / 2 gallons) is detected in the fuel tank. The lamp will come on for 2 to 5 seconds each time the ignition is turned ON, assuring the driver that the lamp is working. If there is water in the fuel, the light will come back on after a 15 to 20 second off delay, and then remain ON throughout engine operation.

Purging the Fuel Tank

Cars on which the Water in Fuel light has illuminated may have the water removed from the tank with a siphon pump. The pump hose should be hooked up to the 1 / 4 in. fuel return hose (the smaller of the two hoses) above the rear axle or under the hood near the fuel pump. Siphoning should continue until all water is removed from the tank. Use a clear plastic hose or observe the filter bowl on the siphon pump (if equipped) to determine when clear fuel begins to flow. Be sure to remove the cap on the fuel tank while purging. Replace the cap when finished. Discard the fuel filter and replace with a new filter.