Nanni 4.390 advice please

[Falling Star]

Hi all,

Can anyone advise me please? My Merry Fisher 805 has developed a fault as follows:

The engine starts easily every time and seems to run for the first few minutes without any excessive smoke or problems. After around 3 or 4 minutes at a fast tickover (800 revs) it starts to splutter and produces a lot of white smoke. This continues for a further few minutes after which it improves. When testing under load she will achieve around 20 knots and seems quite responsive. Hardly any smoke. Return to the marina and all is well again at tickover.

Start her up a few days later and it is the same sequence as before. Starts, runs ok for a bit, loads of smoke/misfire, then OK again. The engine is a standard Nanni 4.390, around 5 years old, with 400 hours on the clock.

The filters were changed recently and a visual check of the fuel indicates that there is no water. The injectors have been removed and new nozzles fitted. No improvement.

What should I check next?

All ideas welcome. Thank you.

 

[Firefly625]

Welcome to the forum..

Hopefully the experts will be along any time soon, but at least I will bring your post higher up the page for the time being! My only comment would be is it white smoke, or is it steam? Could it be something as simple as the exhaust gases now hitting colder air on exit than throughout the summer? Although if spluttering I would think its fuel related... but you are not noticing any decline in performance higher up rev range....mmm...

 

[ulyden]

Hi

Is there any glow plug system on this engine? I have seen that a period after glow system is turned off there can be some white smoke on prechamber engines. Do this engine have prechamber or direct injection?


Anything indicating a heating /glow plug when starting the engine?

Think i have heard about to short glow times on yanmars or people turning it of to save battery.

 

[PaulGooch]

Hi

Is there any glow plug system on this engine? I have seen that a period after glow system is turned off there can be some white smoke on prechamber engines. Do this engine have prechamber or direct injection?


Anything indicating a heating /glow plug when starting the engine?

Think i have heard about to short glow times on yanmars or people turning it of to save battery.

The base engine is a Toyota 1KZ-TE as fitted to the Landruiser Colarado/Prado, 1996 to 2002. It is an indirect injection engine and does have glow plugs, they are short duration but that isn't usually an issue. I have the same engine, it isn't suffering excess smoke.

I've discussed this with the OP via PM prior to him posting and he tells me the smoke is quiet excessive.

 

[ulyden]

Do the fuel pump have any cold start functions as advansed timing?

If yes what is controlling it?

Are the glow plugs having any post glow function?