Mikuni heating

[DustyDave]

Hi,

 

I tried the mikuni heating on my boat for the first time today. It just spat out lots of white smoke from the exhaust. No sign of it firing up properly (although it did make plenty of noise - just didn't get to that jet noise). The other thing I found was that it was dripping fuel (which is probably why the isolation valve was closed).

 

What can I do to find out what is wrong without paying for a proper service?

 

Cheers,

 

Dave

[Robbo]

I tried the mikuni heating on my boat for the first time today. It just spat out lots of white smoke from the exhaust. No sign of it firing up properly (although it did make plenty of noise - just didn't get to that jet noise). The other thing I found was that it was dripping fuel (which is probably why the isolation valve was closed).

 

Shouldn't drip fuel, so I would find the cause of that first.

 

Here's a troubleshooting flow diagram for the MX40... http://www.mikuniheating.com/pdfs/MX40_Flow_diagram.pdf

[Lampyrichard]

Hi,

 

I tried the mikuni heating on my boat for the first time today. It just spat out lots of white smoke from the exhaust. No sign of it firing up properly (although it did make plenty of noise - just didn't get to that jet noise). The other thing I found was that it was dripping fuel (which is probably why the isolation valve was closed).

 

What can I do to find out what is wrong without paying for a proper service?

 

Cheers,

 

Dave

 

 

Agree with Robbo, it definitely shouldn't drip fuel!

 

See this thread MX 40 service manual for links to some scans of the service manual I've put online & the offer of a pdf copy from Doorman.

 

When mine was doing something similar when we first got Zulu, it turned out the burner chamber was full of soot & crud & the 'wick' was burnt out. The flame sensor eye was also covered in soot, so the brain assumed the fuel wasn't burning & so shut down. A simple strip own , clean & new wick from mikuniheating sorted it out.

 

Regards,

 

Richard

[GUMPY]

Where is the fuel dripping from?

White smoke on start up is usually unburnt fuel.

If the installation has not been done exactly to the instructions then the fuel can siphon into the combustion chamber when the unit is off and just sits there until it fires up and then doesn't burn because there is to much fuel.

 

So easy test, turn off the fuel and keep trying to start it until it no longer gives out smoke, you will need a good battery, or alternately take the thing apart and dry it out.

 

Then turn fuel back on and start it immediately, provided that it hasn't gunked up the combustion chamber to much it should fire and will still smoke for a bit until all the fuel is out of the chamber.

 

To prevent this happening Mikuni supply a solenoid valve that shuts off the fuel when the unit is off.

[nb Innisfree]

Where is the fuel dripping from?

White smoke on start up is usually unburnt fuel.

If the installation has not been done exactly to the instructions then the fuel can siphon into the combustion chamber when the unit is off and just sits there until it fires up and then doesn't burn because there is to much fuel.

 

So easy test, turn off the fuel and keep trying to start it until it no longer gives out smoke, you will need a good battery, or alternately take the thing apart and dry it out.

 

Then turn fuel back on and start it immediately, provided that it hasn't gunked up the combustion chamber to much it should fire and will still smoke for a bit until all the fuel is out of the chamber.

 

To prevent this happening Mikuni supply a solenoid valve that shuts off the fuel when the unit is off.

 

 

Fuel shutoff valve

Edited August 28, 2011 by nb Innisfree

[GUMPY]

Fuel shutoff valve

The very item

They come as standard on the MX60

However if the installation is done correctly then you can manage without one, its just that a high percentage of installations are not done correctly!

[nb Innisfree]

The very item

They come as standard on the MX60

However if the installation is done correctly then you can manage without one, its just that a high percentage of installations are not done correctly!

 

Mine didn't!

 

But then in my case I was able to see that it didn't make any difference to my probs, it runs fine now on ULSD.

[DustyDave]

Thanks for all the info. As suggested I ran the heating yesterday with the fuel supply cut off until the white smoke disappeared (I hid while swmbo drove the boat while stinky white smoke was belching out). When the smoke stopped coming out (in any great amount) I turned the heating off, opened the fuel supply, and turned it back on. Everything appeared to work (although a very small amount of white smoke still came out - and I couldn't hear it as the engine was running - but rads started to warm up). I now need to find out why the fuel is leaking. I'll take a look at the weekend to see if I've got a solenoid fitted.

 

The previous owner told me the heating wasn't working (and he'd supposedly cleaned it out and fitted some new parts). What he didn't know was how stuffed the batteries were. I've recently replaced them hence my playing with the heating.

 

Dave

[nb Innisfree]

Thanks for all the info. As suggested I ran the heating yesterday with the fuel supply cut off until the white smoke disappeared (I hid while swmbo drove the boat while stinky white smoke was belching out). When the smoke stopped coming out (in any great amount) I turned the heating off, opened the fuel supply, and turned it back on. Everything appeared to work (although a very small amount of white smoke still came out - and I couldn't hear it as the engine was running - but rads started to warm up). I now need to find out why the fuel is leaking. I'll take a look at the weekend to see if I've got a solenoid fitted.

 

The previous owner told me the heating wasn't working (and he'd supposedly cleaned it out and fitted some new parts). What he didn't know was how stuffed the batteries were. I've recently replaced them hence my playing with the heating.

 

Dave

 

If repeated and failed starts are made it can eventually flood.