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Yanmar 3GM30. Engine stalls when warm but not when cold.

R

ralph60

New member
Hi Guys. My Yanmar 3GM30 starts and runs well when cold but after it is fully warmed up it has 2 problems.
1) Slow response to throttle (takes a few seconds before it revs up).
2) When brought back to idle (say when changing from forward to reverse) it dies.
If I turn the engine off for a few minutes it runs well again.

Any thoughts on what the problem is?
 
I would suspect a vapor lock in the fuel system.
Disconnect the fuel return and run the engine and let the return go into a cannister.
If return disappears or bubbles occur, change filters, check fuel pick-up in tank.
If that does not help, a new feed pump might be needed.
The return is needed both for lubrication and cooling of the injectors. If to little return, it starts vaporizing and problems like you describe happens.
 
Hi I have the same problem or similar on a 100HP Yanmar...all fine cold but when it runs for few hours it stalls at low rpm when shifting gears getting to slip or anchoring...ay more ideas there ? Thanks for help...
 
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