Join Date: Sep 2007
Location: Pasadena Md - Magothy side
Thanked 31 Times in 31 Posts
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Re: Diesel stalling, about to Give Up
Loss of RPM can be many things, most likely air leaking into the fuel. It could also be poor quality fuel. I doubt it was ever the pump. I have a yanmar 44, it doesn't even need to have the electric pump turned on to run, the mechanical (cam driven) pump runs it fine.
What's the status of the filter?
I would change out the filter - if there is a lot of water in the bowl, drain it. Make sure the entire fuel system is bled of all air.
Then fire up the pump (just the pump, not the engine) - and again check the filter, just look through the clear part and you should be able to see fuel swirling around. Let that run a hour or so - it's just 'polishing' your fuel (pulling from the tank and returning it via the return line.
Check the filter - look specifically for air bubbles. I'm assuming you have a clear portion on the filter, check for water in the drain bowl. If you don't have bubbles and don't have water and the fuel filter itself isn't a crud covered mess start the engine and bump it to 1500 rpm, let it run until your RPM drop thing happens, or if it doesn't then let it run for as long as you need to be confident you've found and fixed the problem.
Do the bubble/water check every time (turn on the pump when you get to the dock and let it run until you are ready to pull out, then check for bubbles) before you go out until you are happy. Properly filtered and dewatered diesel should be fine after two years.
If you become convinced you must drain the fuel get a jerry can, disconnect the fuel return from the tank and fill the jerry using the fuel pump. Me, I'd toss in a additive and go sailing.
Lessons learned are opportunities earned.