Hi,
we are currently cruising The
Bahamas with our
Lagoon 47 equipped with two
yanmar 3ym30. Unfortunately one
engine stopped working and I can't get it running again. When it fist stalled I found out, that the previous owner attached the
fuel supply line from the tank and the
fuel return line to the tank kind of switched (supply line to the filter, return line to the feed
pump. I corrected that issue, replaced the filters, bleeded the lines and the
motor ran for a few days well – until it stalled again. I then discovered vey little to no
diesel flow through the feed
pump (even though the tank sits higher than the engine) and after opening the feed pump I found it completely clogged. I cleaned it and the flow to the injection pump is now great – but the
engine will still not start. It always only fires a few times now and then.
My suspicion is, when i switched the lines the feed pump was already clogged and the injection pump sucked the
diesel from the now correctly installed (but unfiltered) return line instead of from the supply line. Is that possible? I believe return line and supply line lead to the same place within the injection pump?! (The return line in my setup would in fact be able to deliver diesel constantly because it seems to be attached to the bottom of the tank. Is that acceptable or should it be connected to the top of the tank to make any backflow impossible?). I believe, as the fuel through the return line is not filtered, there is now dirt in the injection pump what is the reason that the engine won't start.
I there a way to clean the injection pump while installed? Can I carefully unscrew each of the three valve assemblies from the top of the injection pump (where the high pressure lines are attached) to see if dirt has accumulated and reassemble everything in the same order with all shims?
I would vey much appreciate any help and suggestions to get the engine running again.
All the best
Uwe Boerst