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Post by jubjub on Sept 22, 2019 12:27:57 GMT
Sods law is just when I might start to need it my Mikuni heater won't work (please don't go into the whys and wherefores of Mikunis, it came with the boat so I am stuck with it for now). Started up a couple of times just to warm the boat in these colder mornings. Then got an unusual whining noise but worked, next day dead. Checked and replaced all three fuses and the LED switch. Checked all the wiring. Still dead. Diagnostics pointed to new control unit so managed to pick one up and replaced.still dead. Almost like no power to the switch.someone suggested the air pump? Any other help glad appreciated.
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Post by Deleted on Sept 22, 2019 13:34:37 GMT
Unusual whining noise then dead sounds like one of the pumps is nackered either air or water.
These units don't like air locks in the water side. Will go into shutdown mode quite quickly if there is air in water. Overheat cutout.
Other thing is the flame sensor clean?
That type of heater is a fire hazard so they are rigged up with loads of safety devices which do fail. Quite an old unit the MX40. 20 years+ probably. Date code on the original control box.
If the unusual whining noise has a slight whistle to it then its probably the shutdown mode which means overheat, or flame sensor.the shutdown puts the air pump on full whack to clear out the combustion chamber assuming that the pump is ok. If pump faulty it will just stop without the shutdown. The shutdown is normal. Maybe this is the whining noise? Obvs if you are close to the unit more likely to notice the extra noise.
It could just be the flame sensor as it a light sensor which tends to get blackened by burnt diesel...
Its on the end in a rubber housing secured by a piece of spring steel and scews. Take it off and wipe it then replace it. might sort it.
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Post by lollygagger on Sept 22, 2019 13:52:52 GMT
Is this a diesel thing? I'm sure you're not as daft as me, but after giving my diesel powered heater a thorough overhaul trying to get it to run I realised it took it's fuel from higher up the tank than the engine and had simply run too low.
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Post by Telemachus on Sept 22, 2019 14:27:12 GMT
Sods law is just when I might start to need it my Mikuni heater won't work (please don't go into the whys and wherefores of Mikunis, it came with the boat so I am stuck with it for now). Started up a couple of times just to warm the boat in these colder mornings. Then got an unusual whining noise but worked, next day dead. Checked and replaced all three fuses and the LED switch. Checked all the wiring. Still dead. Diagnostics pointed to new control unit so managed to pick one up and replaced.still dead. Almost like no power to the switch.someone suggested the air pump? Any other help glad appreciated. These are powered all the time, but only come on when the switch is turned on. There should be a supply from the battery, via an in-line fuse or the like, to the unit. So check that you have 12v where the power leads enter the heater, when you are trying to fire it. If it has previously locked out, you have to remove the power (eg take the inline fuse out) before it will have another try. Just switching it off and on at the switch doesn’t cut it. Having done that, what is the diagnostic LED flashing (if anything)?
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Post by Deleted on Sept 22, 2019 14:40:46 GMT
Is this a diesel thing? I'm sure you're not as daft as me, but after giving my diesel powered heater a thorough overhaul trying to get it to run I realised it took it's fuel from higher up the tank than the engine and had simply run too low. Another thing which happens with these is that the tiny little fuel filter before the ticker pump gets blocked. This also leads to shutdown cycle kicking in. Mikuni MX40 actually does not want a head of diesel. This can cause flooding which can be quite nasty
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Post by jubjub on Sept 22, 2019 14:42:33 GMT
Is this a diesel thing? I'm sure you're not as daft as me, but after giving my diesel powered heater a thorough overhaul trying to get it to run I realised it took it's fuel from higher up the tank than the engine and had simply run too low.
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Post by jubjub on Sept 22, 2019 14:52:46 GMT
Hi it isn't the diesel as I never let my tank get that low. I have removed and replaced the inline fuse (30) and the other two fuses (3 & 7.5). Having said that the original inline fuse had gone.I will try the other suggestions. As to the switch, I replaced that just in case. I have three wires from the Mikuni,white, green and blue/yellow. The switch has 3 connections, 2 silver and one gold I have the green connected to the middle silver spade, the white connected to the end silver spade and the blue/yellow to the gold spade with a 'loop' connection to the white. Is that correct for an LED switch (just checking everything)
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Post by Deleted on Sept 22, 2019 15:00:53 GMT
When you switch it on with the remote switch does anything happen at all?
If there is a click from the control box this might indicate that the switch is working (relay) but the automatic safety checks have detected a problem.
If there is no relay click then I would say the switch itself has a problem.
A common solution to this issue is to install a device which can accept wood or coal as a fuel source.
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Post by lollygagger on Sept 22, 2019 15:11:23 GMT
Hi it isn't the diesel as I never let my tank get that low. Well that's the thing, for my boat the outlet for the heater is so high that when it runs out I can only get 40 litres in. It certainly tricked me. I guess it's done this way to prevent the heater using all the fuel and getting stuck with no diesel for propulsion.
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Post by Deleted on Sept 22, 2019 15:19:38 GMT
Its definitely a good arrangement. Assuming you have a solid fuel appliance and are not iced in in the middle of nowhere.
I don't think they do ice these days so its probably OK.
Seems odd in a way for prop to be more important than heating but if sharing the tank I would always do it like that.
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Post by jubjub on Sept 22, 2019 15:42:53 GMT
I cannot, although I know what it looks like, find an fuel filter. I have checked the fuel lines and they are clear. The glow plug is OK and clean but the boss is slightly dirty (now need a new gasket !!!) Located the fuel pump but haven't removed it as it is a bit tricky to get to. I think that is as far as my limited skills will take me so looks like I will have to call someone out. If anyone knows anyone let me know I moored at Crick at the moment Thanks
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Post by Deleted on Sept 22, 2019 15:48:00 GMT
There is a tiny fuel filter on the inlet to the fuel pump. You have to undo the union nut the filter lives in there. Its a known issue as it is really small and gets shitted up easily. It sits inside the pipe so if you take off the nut connecting fuel inlet to the ticker pump you should find it. Tiny thing.
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Post by lollygagger on Sept 22, 2019 16:26:50 GMT
Its definitely a good arrangement. Assuming you have a solid fuel appliance and are not iced in in the middle of nowhere. I don't think they do ice these days so its probably OK. Seems odd in a way for prop to be more important than heating but if sharing the tank I would always do it like that. Prop is definitely more important or how would you drive your boat to get fuel if the heater used up all the diesel? That would be annoying.
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Post by Deleted on Sept 22, 2019 16:42:41 GMT
If you were moored permanently and someone delivered your diesel it would be less important but then it would also be pointless having a propulsion engine.
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Post by jubjub on Sept 22, 2019 17:03:24 GMT
There is a tiny fuel filter on the inlet to the fuel pump. You have to undo the union nut the filter lives in there. Its a known issue as it is really small and gets shitted up easily. It sits inside the pipe so if you take off the nut connecting fuel inlet to the ticker pump you should find it. Tiny thing. OK I'll have another look tomorrow Thanks
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