I have a 1961 292 in one of my '54 Fords with the original factory type double action AC fuel pump.  I now have a massive fuel leak.  Every time the pump activates, a large stream of fuel squirts out of one of the vent? holes located just above where the fuel line connects to the pump.  I have never had that happen before.  What does that show is wrong with the pump?  Also, I will probably need a replacement and I want to stick with the AC factory type.  AC pump #'s 4206 and 4486 look almost identical but one is for Ford and one supposed to be for Mercury.  What is the difference and will either pump work on my 1961 292?   Which is the correct AC pump number for this engine?  Thanks