and you tested this petcock HOW?<br />
if you were to remove the fuel line and attach a line to the petcock and run it into a container, then apply vacuum to the vacuum line coming off # 6 carburator. then you would see if it's supplying fuel. if not then your going to need a cover set. which is part #. 16953-MBZ-B51. just keep in mind how you tear it apart. it can go back togather a couple different ways. <br />
Also if you've added a fuel filter inline you could have a kinked fuel line.<br />
those that have installed quick disconects in there fuel lines have also reported problems.<br />
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my bet is a torn diaphram in the petcock..no vacuum equals no fuel.