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Old 06 May 2014, 15:49   #21
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adding oil to the fuel on an autolube motor will weaken your fuel mixture not a good idea premix carbs will have larger main jets to keep the afr correct
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Old 06 May 2014, 16:12   #22
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Originally Posted by beerbelly View Post
adding oil to the fuel on an autolube motor will weaken your fuel mixture not a good idea premix carbs will have larger main jets to keep the afr correct
That was last year beerbelly, and was purely to get us home without seizing engine. I'd put money on it being a false alarm, as it was pumping water and using oil. The fuel tanks have had fresh fuel in them since. The carbs have also been stripped down and rebuilt.
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Old 06 May 2014, 16:54   #23
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Quote:
Originally Posted by RIB-Teccie View Post
May be a bit late in the day but there are some other simple steps to see what is wrong.
Never too late RIB-Teccie.

Quote:
1) run engine with a spark checker installed.
I plan to run a compression test on all three cylinders and test the sparks (new NGK plugs gapped to 1mm) this weekend.

Quote:
2) back off fuel pump from block and squeeze bulb. If petrol comes out of the middle hole, it's the fuel pump.
I'll try this thanks. I replaced the fuel bulb 2-3 weeks ago with a Quicksilver primer bulb and rebuilt the fuel pump last year, all new parts. From previous comments the Tohatsu fuel pump can be suspect?

Quote:
3) at the same time look around carbs for petrol coming out of breathers, if it does it is the float needle or height.
You identified that one of the oil circulation pipes had popped off (first run of the season), probably related to the poor running of the engine. I reattached. I'll check the carbs, when I run it this weekend.

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4) remove airbox and launch boat. Run engine in gear at speed and look down the venturi, if you have a fuel blockage to will see it straight away and which carb.
I'm a 60 mile round trip from the coast - can this be done without putting engine under load, but use a tank (wheelie bin) instead of muffs on idle or light forward gear?

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5) replace airbox and undo the loom whilst running, that will tell you if it is the control box.
Easy one, will do.

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6) I assume fuel system to engine is A1
Boat was new in 2010 from RIBcraft. The tanks (x2) are 25 litre plastic tanks which sit under the jockey seats, and are vented, etc. Fuel hose was new in 2010, Tohatsu male/female fuel connectors are A1. There's a fuel/water separator filter in console that was renewed last year, but I'll check again. From there it goes under the deck and reappears at the transom. I'll test a sample of fuel in a glass jar to see it's not being contaminated with water under deck for any reason. The boat has been swamped before with a rogue wave, and although there's a rubber grommet (witches hat) where the fuel, steering and throttle cables enter the deck - I know that the cables can be wet when I've had to do any work such as haul through new cable. There's a under deck drain screw in the drain-well but if opened it's always dry which makes me think the under deck trunking isn't perforated but a sealed pipe? I digress. The fuel primer bulb is new and I've cleaned the filter reservoir on the engine. Again, I'll check this.

Quote:
7) many electrical problems are intermittent. Whatever the problem with your engine, it is always there so should be findable.
Tracking this problem down has become my only mission in life.

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8) I was never convinced by plug inserts, if you cannot find anything else wrong, it may be back to square 1
The steel plug inserts were installed earlier this year by a local company that are specialists in their field. Previous owner of the outboard had goosed the threads. I purchased the engine in 2010 from Tohatsu dealer, and the threads gave way during routine maintenance at the start if the year.

Thanks for taking the time to reply. I'll post feedback.
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Old 06 May 2014, 17:04   #24
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Thanks Loco.

I have an online service manual for specifications. I don't have a flywheel puller, so no worries regards starting to alter the main electrical components. I'll check the basics first.

The overheat alarm if that's what it was when it sounded is likely to be an electrical fault and I'm sure is a red herring. Water passages are clear (remember cylinder head has been off), plus impeller was renewed last year and new thermostat. The tell-tale is like a Clydesdale horse pee, and it isn't warm.

I'll reset the pilot screws on the carbs back to 1 5/8 from lightly seated as per factory specification. I haven't adjusted the idle screw on the middle carb.
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Old 11 May 2014, 09:29   #25
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Worked on the engine this weekend. To compound matters I've started work on the auxilliary engine now too. The impeller was totally goosed (this engine rarely gets used) but had compacted salt crystals under the water-pump which I'm putting down to seawater wash when underway. I'm renewing the impeller and will flush even if the auxilliary engine hasn't been used. Valuable lesson learnt.

Back to the original thread. I tested the cylinder pressure and it reads 120psi or thereabouts across all three cylinders so very even.

Next I installed new spark-plugs (NGK) with correct gap. Also stripped fuel pump down again, cleaned fuel filter on engine and tested fuel for water direct from the fuel line. All fine.

When the engine was running I checked the spark by removing the caps one by one. The top cylinder has a great spark (can literally feel it on removing HT cap). Other two made audible differences to engine running, but that top one was punching above its weight (great spark) which makes me think the middle and lower cylinder coil packs are weak.

I did think it could be the exciter coil under the flywheel, but surely if it was worn, then the spark to all HT leads would be weak?

I also disconnected the electric loom at engine side while running and the engine stopped.

I'll check voltage to engine later today while running at stopped and give readings.
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Old 15 May 2014, 17:35   #26
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Still fault finding before finally throwing in the towel. Does anyone know the resistance for the coils on the M60C in ohms. The factory guide I have says 3,300-5000 secondary (earth or black cable to plug cap). I'm getting readings of 7,900 - 8,200 ohms across all three coils. The guide I have is for models up to 2000 - but pretty sure there's not much difference for a 2006 unit.

Also - does anyone know if the overheat sensor can be tested? Part is 3N4-76172-0, and yes you guessed its expensive to replace!

The reason I mention it - is it apparently can put the engine into limp mode and reduce revs. Just wondered if it could be the cause?
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Old 15 May 2014, 18:01   #27
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Tohatsu one step away from being an anchor!

Just a couple of thoughts....

Are the plug caps of the resistor type? It may account for a different reading than the book. As long as the reading are all similar I wouldn't worry about the coils.

Most overheat sensors simply go to earth to make the circuit, test in VERY hot water, engine will still run with it unplugged if you want to rule it out.
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Old 15 May 2014, 18:01   #28
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i've got a 5hp tohatsu if you need something to tide you over in the meantime....
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Old 15 May 2014, 21:47   #29
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Spartacus,

Are all spark plug coils independent small ones or it's a single unit with 3 cable exits ? All 3 coils could be firing ok, but in order to test the gap strenght you need a gap tester. It's a electric device, one end connects to plug cable, other end to ground.

Has middle points facing each other which are adjustable in lenght. Needs to be adjusted to factory specs to check gap color and intensity. This test will show if current ignition coils are working in proper order.

Happy Boating
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Old 16 May 2014, 01:36   #30
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Strange wires from CD unit M90A

Not sure how equal the wiring is on Your engine compared to a M90A, but if it is, and You disconnect the black&yellow wires(comming out of the cd box) from each other, i believe alarms & all safe mode functions will be disabled. This might help locate problem if a faulty sensor is making some tricks.
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