Dirty fuel injectors could. A partially clogged injector wouldn't atomize the fuel adequately so you wouldn't have proper combustion in the cylinder which would lead to rough operation.
Diesel intermittent Low RPM stall
- Thread starter Monterey385
- Start date
What are your RPM at idle? To slow of an idle can cause engine stalling. I idle my engine at 850 to 900 RPM. Let's start at basics, replace the primary and secondary fuel filters to include the water separator, it does not matter if you recently replaced them as running low on fuel will help stir up sediments which can clog the filters prematurely. It is possible the screen in the fuel pick up tube might be partially clogged so blowing air back through the fuel line may help clear it. Don't use compressed air at high pressure as you may damage the tank. always open the filling cap. Repeat the procedure for bleeding air out of the fuel lines as sometimes it is hard to purge all the air out. Check for fuel leaks as where fuel leaks out usually air can come in after shutdown.
On my old boat I installed a racor 500...... engine was a 3hm35f that ran rough at idle to the point at low idle it felt like it would cut out. I filled racor 3/4 and rest with diesel and after that she purred at idle with no hint of a cut off. After that whenever I would change filter I would add sea foam 50/50. Never a problem. But I do know people that do the entire racor filled with sea foam.
Good stuff if you ask me.
Good luck
Greg
This almost has to be air in the fuel system or maybe the idle is set too low and when you go to advance the throttle it briefly reduces the fueling due to play in the linkage and it dies.
Maybe your idle stop screw on your throttle cable needs to be adjusted? Is the idle RPM at the factory spec when it is running as you describe "normal." You might want to advance your throttle just a bit before you start the engine so it is running at a little higher RPM initially then bring it back to idle after it runs for 30 seconds or so. Do you have glow plugs? It sounds like you don't if you crank it right away. A diesel depends on compression of the air to reach the combustion temperature of the fuel mist sprayed in by the injectors. A cold engine takes a while to heat up and once warmer it will be more apt to run better. Probably why when it restarts it keeps running. Check your compression too, if it is low it will effect your combustion temperature. Might need to adjust a valve or two, hopefully not a ring issue.
I think just about every boat I have owned had to have the throttle advanced slightly before starting. It just became a regular habit. The 2GM20 Yanmar in my present boat is no exception. At startup the engine seems to run on one cylinder for a couple of seconds before the second cylinder fires. At that point, the engine smooths out and the throttle lever can be set back to normal idle. After that, starting is fine in neutral the remainder of the day.
My 4-108 manual says start at WOT. I usually use about 1/2 with 1 hand on the throttle and 1 on the key.
