A molten metal supply system includes a plurality of injectors each having an injector housing and a reciprocating piston. The air inflation tube of the air pump has a dual direction air inflation capability, that is, inflation and deflation, and the pressure releasing and air pumping are done by the same tubular body to solve the problem of excessive tire pressure without removing the air inflation tube. In an alternate embodiment of the invention, cooling air can be taken from the intake manifold system of a turbocharged engine downstream of an air-to-air aftercooler and ducted to the cooling jacket in the turbocharger bearing housing. The hub is biased between an extended position, such that the distal end of the needle is exposed and the movable projection is releasably disposed with the cavity, and a retracted position whereby the distal end of the needle is disposed within the housing.