Abstract: A fuel supply system having a pump for drawing and discharging fuel from a tank and a filter for catching foreign matter in the fuel. A housing has a fuel outlet and supports the pump. The pump has a fuel intake port and a fuel discharge port. A fuel passage is located in the housing and connects the fuel outlet with the discharge port The filter is located in the fuel passage. The filter has a filter case and a filter element therein. The filter case is located in the housing spaced from the inner wall thereof.

Abstract: A low-pressure fuel filter is disposed in a fuel-return pipe from the fuel pressure regulator. In a portion of the fuel-return pipe between the fuel pressure regulator and a fuel element of the low-pressure fuel filter, a bypass device which includes, for example, a jet pump or an aperture may be provided so that fuel can flow back to the fuel tank, bypassing the fuel filter when the fuel filter is blocked.

Abstract: In a fuel supply system, pressurized fuel is supplied to a delivery pipe from a fuel tank and distributed to fuel injection valves. The delivery pipe includes a main pipe in which upper and lower chambers are defined by a partition wall. One of the fuel injection valves is capable of receiving fuel from both the upper and lower chambers via a particular passage, while the other fuel injection valves are arranged to receive the fuel only from the lower chamber. Bubbles are supplied only to that one fuel injection valve and discharged therethrough. Accordingly, the other fuel injection valves can achieve the normal fuel injection even when the bubbles are present in the delivery pipe. It may be arranged that the partition wall may be omitted. It may further be arranged that the fuel supplied to the delivery pipe is prohibited from returning to the fuel tank and thus is all supplied to an engine via the fuel injection valves.