Nanni diesel - help!

[Vadie]

Hi, I'm new to this forum as I've just bought my first yacht - a 1990 Mottle 820.
My Nanni 14hp 2.4HE is not behaving itself.
What happens is:
it starts 1st time every time - good
it revs up and down fine when in neutral - good
when in forward or reverse, it runs really well, sounds great - good
The issue is when i slow down to pick up a mooring, pull in to a wharf etc, it won't allow me to accelerate again, it's like it gets stuck in really low revs and sometimes stalls.
Sometimes if i put it back to neutral and allow the revs to catch back up to normal idle speed it 'may' let me accelerate- but usually not.
The only fix is to kill the engine and restart, then it will accelerate.
You can imagine this is REALLY STRESSFUL when the wind is blowing and other moored boats are around as I'm without power for short periods of time.
Has anyone else experienced this?
A farmer friend of mine says it could be the governor???
Any hints would be most welcomed
Cheers

 

[Oily Rag]

It may well be the governor or some complicated problem, but please check for clean fuel and a clean air filter. Check also that the previous owner hasn't left a winterising rag in the air filter.
Good luck!

 

[RichardS]

Oily Rag is right. First check all the relatively simple stuff. Air filter, fuel filters, fuel tank vent, fuel supply, exhaust elbow, cable linkages and operation. Once all these are ruled out, start thinking about governors, injectors etc

Richard

 

[Amlov]

It could be a simple problem that the tick over is set too low on the fuel rack. Usually the symptoms are that engine hunts and runs slow when taken out of gear but then slowly picks up to normal revs.

A question: if when you slow down and take it out of gear can you get the revs back to normal by disengaging drive and giving it a blip of throttle? If so, I would suspect the fuel rack adjustment. Frequently people try to set engine tick over on the throttle linkage which is incorrect.

Anyway, you need to be aware that on the Kuboto base engine the tick over is set on the fuel rack NOT by the throttle linkage. To set this you unclip the throttle linkage and find the fuel set screw on the front of the fuel pump (usually under a dome head nut), with a warm engine adjust this to give about 900rpm and then put the engine in gear, with the throttle linkage disengaged. Check the engine runs smoothly and the revs don’t drop too much - otherwise adjust the screw a bit more. Then put the throttle linkage back on and hopefully things should be improved.

Of course, it could be any of the problems that the proper engineers have highlighted.

 

[Bilgediver]

Hi, I'm new to this forum as I've just bought my first yacht - a 1990 Mottle 820.
My Nanni 14hp 2.4HE is not behaving itself.
What happens is:
it starts 1st time every time - good
it revs up and down fine when in neutral - good
when in forward or reverse, it runs really well, sounds great - good
The issue is when i slow down to pick up a mooring, pull in to a wharf etc, it won't allow me to accelerate again, it's like it gets stuck in really low revs and sometimes stalls.

It sounds like the throttle governor slow running settings have not been set correctly. The correct setting device for the governor is the stop on the engine governor to which the Teleflex is connected It should be a screw with a spring friction device. Some people adjust the Teleflex itself which as in your case is not consistent. and exactly what you describe can happen especially if the slow running stop on the side of the governor speed lever is not set correctly.

Check the slow running screw on the governor speed lever and turn it slowly when the engine is running till you get the idle to about 850 RPM . The engine should then always return to the correct idle speed. Please keep us advised.

 

[Vadie]

wow! great replies. Thanks so much.
The fuel is clean and the oil filter is new. I'll definitely check the air filter for a winterising rag (which i've never heard of before ).
I'll also check the fuel rack adjustment suggested by @Amlov . And to answer his question - unfortunately no, i can't get the revs back even in neutral most of the time, it's like it's just stuck in below idle speed and eventually stalls.
I guess the thing that makes me think it's something to do with the governor is that killing the engine and starting it again 100% of the time 'resets' it, and then I can accelerate in gear or in neutral.
I'll definitely check for the slow running screw and other suggestions by @Bilgediver
Can't wait to get back on board to try this all out.
Cheers