Fuel Filter

There are three types of fuel filters:

• Carbureted engines use a conventional, inline fuel filter with ordinary clamps and lines.
• Fuel injected engines use a special, high pressure filter with banjo fittings. Note that the pressure in the system must be relieved before attempting to remove the filter in this type of system.
• The diesel engine uses a filter assembly that not only filters sediment and water from the fuel but also, under certain conditions, warms the fuel to prevent fuel line blockage. The filter housing is equipped with a water level sensor which will illuminate a dash light, warning the operator that the level of trapped water within the filter has risen to capacity. The filter then needs to be drained as soon as possible, after the dash light has illuminated.

The fuel filter must be replaced at least every five years or 50,000 miles (80,000 km). This is a maximum replacement period. However, since the amount of dirt and, in the case of a diesel engine, water in the fuel varies greatly, the filter should be replaced whenever you suspect it to be clogged. Typically, the symptoms of a clogged filter are a lack of engine performance under full throttle conditions, especially at high rpm, even though the engine operates normally under moderate driving conditions. With severe clogging, the filter may cause poor running under virtually every operating condition but idle. One way to check out the filter is to follow the steps below for removal and then drain the contents out of the filter through the inlet. Drain the filter into an aluminum can. While it is normal for a light concentration of particles or a few drops of water to be trapped in the fuel on the inlet side of the filter, large amounts of water and heavy concentrations of dirt indicate dirty fuel and, probably, a clogged filter. If you find a great deal of dirt trapped in the filter, it is a good idea not only to replace the filter, but to have the fuel tank drained or pumped out as well.