Abstract: An apparatus for detecting air and water in and eliminating air and water from the fuel in diesel-type internal combustion engines includes a main body which is composed of an upper part, a cylindrical and transparent intermediate part, and a lower base part. The upper part defines five openings of suitable diameter. The first opening is connected to a connection tube for taking in fuel from a fuel tank. The second opening receives a suction tube immersed in fuel contained in the intermediate part and in communication with an injection pump. The suction tubes defined an inlet hole at the lower level within the intermediate part which ensures that fuel is conducted to the injection pump without air. A third opening is in communication with a fuel return leakage of the injection pump. A fourth opening receives a warning probe member which includes a float sliding in a guide member. The float controls two magnetic switches by sliding in the guide.