Yanmar 1gm10 loosing revs

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choppy

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Light winds over the weekend meant a fair few hours were put on the engine after a harder than usual 2 hours of work she started not to respond to the throttle immiediatley tending to either drop off or lag & then gather revs & at one point they droppd almost down to what I would expect @ tick over with 2/3 throttle. This cleared for long periods (Was being gentle at this stage) but would return with no pattern. It did seem more frequent after running for 1-2 hrs & was experienced (to a far lesser extent) in neural.

Does not look/feel like anything round prop (did discover anode loose though) and a quick look at water/cav/seperator filter seemed 100% clean diesel. Next step is to get out to the boat & change fuel filter but I'm pretty sure the fuel is clean. I have added Fuel set but after that would appreciate any wisdom as to what to look @ next.
 
i had exactly same problem on same yanmar engine
coming up to holyhead from Plymouth
turns out i had bacteria in the fuel which was blocking filters
on quick inspection of glass bowl ,looked fine .but after jet washing tank and change of both filters .now runs sweet.
i had to floor the engine when it was playing up .it would then eventually come back upto full revs.then after different amounts of time die down again.then repeat above.not much fun at 3:30 in morning in force 8 next to south stack (rip tides)
check that fuel set is intended to kill bacteria as well
my diesel tank was fairly easy to take out so for me was best option.it might be easier for you to put in loads of fuel set and have lots of filters handy,till its cleared from tank
good luck
 
Might be wrong but I think Fuel Set is just a moisture gobbler to reduce risk of bacteria growth - something like Soltron is for gobbling bacteria.

I'm sure if this is wrong somebody will post pretty quickly!
 
Since you mention it - I too would like to know the detailed difference. I'd got the impression that Fuelset killed em and did something about water while Soltron stopped em clumping together as well but I might just be adding to the confusion.
 
Soltron does kill microbial growth, it just does it in a different way - it does not kill them by poison it kills them by breaking them down so small they pass through the filter and are burnt in the engine.
 
Now, you cannot expect me to comment on a rivals product now can you? /forums/images/graemlins/wink.gif
 
If changing the filters doesn't do it, it could be clag in the lines, or a partial blockage due to a kinked or collapsed line - possible an old fault combined with clag.

Another possibility is a flake of rust over the fuel take-off from the tank. Some take-offs also have an undocumented mesh filter in them, which can get blocked.
 
Does anyone have any experience on small marine diesels of using a vacuum guage downstream of the primary filter to detect blocking before it causes problems? It seems sensible but I have never seen it done.
 
Actualy it emulsifies the water, so its still there but the dropplets are so small that they pass thru the water seperator.

Now the problem with this is that some of the larger dropplets of water in the suspension (in the week that you are away from the boat) can drop out of the fuel to form water again - so now you have water in your injection pump and injectors.
 
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