The most common cause of Isuzu fuel injector failure is clogged valves that become choked with the residue of your engine operations. Over time, these deposits can build up and clog the injectors. These deposits are part of the normal operations of an engine, so detergents are added to gasoline to help keep the injectors clean. Those detergents can only work so far, especially for cars that driven mostly for short distances. These deposits tend to affect older models the most; they will collect in the combustion chamber, fuel injectors, valves and other parts of the fuel system. The residue is mostly deposits left over from the gasoline, which is a mixture of many different hydrocarbons. The biggest offender among those hydrocarbons are oilfins. These are heavy, waxy compounds, making them more prone to coat the inside of the fuel system. When you turn off the engine and it cools, the fuel residue in the injector nozzles evaporates, leaving the waxy oilfins behind. At that point, because the engine is not working, there is no cooling air flow through the ports and no fuel flow through the injectors to wash away those deposits. The heat will bake the oilfin into hard varnish deposits. That accumulation of deposits eventually leads to a lean air-fuel mixture in the combustion cycle, which causes engine detonations, knocking, loss of power and a drop in your gas mileage.