[Healeys] Gas dripping from Manifold rear Drain pipe

[John Soderling]

My friend's 1958 BN4 (HD6 carbs) suddenly started to run poorly with little
power and we could smell fuel vapor.   I suspected lack of fuel, and upon
investigating found that the fuel pump (after market) clicks continuously and
fuel was dripping from the inlet manifold's rear drain pipe.

What are the most probable causes of this?  Thanks.

Vrooom vrooom,
John