In this video, I show the origin of a diesel fuel puddle I recently observed in our engine bilge. The engine is a 1976 marinized Ford Lehman 120HP diesel with a Simms fuel injection pump.
After a few hours runtime, I’d see a little puddle of diesel fuel in the center of the bilge. The location baffled me, as most of the fuel lines, pumps, filters, and so on, are located on the starboard side of the boat.
The leak source turned out to be a bleed screw on the Simms pump that I hadn’t tightened enough when I last changed the fuel filters. It must have loosened slightly and begun to weep diesel. The slow diesel leak found a path down the engine and under it before dripping into the bilge. Thankfully, it was an easy fix to tighten the screw a little more. Since then, we’ve run for 9 hours and there has been no leak.