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Old 16 July 2013, 06:29   #1
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Mercury 50, should i have this water

Hi

My mercury 50 outboard has been working fine up until this weekend and it then started running rough at idle and stalling, starts fine then cuts out again. it will keep running at higher revs. Not sure what age but it is the old black wrap around cowl


After investigation and a good clean out of carbs etc problem has persisted, maybe i am being stupid but after removing the pressure pipe that leads from the fuel pump to the crank case I found water in it and when the engine was started a steady stream flowed

I presume this is not good news but can anyone tell me the likely cause and possible solutions, picture attached showing the hose that the water flowed from

Any advice and help greatly appreciated!
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Old 17 July 2013, 16:49   #2
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Please anybody?
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Old 17 July 2013, 17:28   #3
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That pipe looks like it comes from the top of the mid section rather than the crankcase, so I suspect its a water cooled lift pump. Where does the top pipe run to?
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Old 17 July 2013, 17:32   #4
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Think that's a water cooling pipe from memory. I can see a problem in the form of a kink in the pipe from the filter to the pump.
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Old 18 July 2013, 05:45   #5
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Pretty certain it's +1 on tyhat being a cooling hose (50 & 60 are almost identical in most respects, but it's been a while since I took that bit apart! )


- back to your running rough - did it decline slowly or was it a "step change"?

Next silly Q - I assume it didn't start playing up after a long period of use at or around idle?

Looking at your photo those HT leads look quite "original" - have a wee check of them - mine ran like a dog until I found one of them at the coil end had separated from the connector and was literlaly being held in place by the rubber cap! Another wasn't too far behind.

Pull all the plugs & let us know if any are particularly manky when compared to the others. - That is your suspect lead / plug!

Also when did you last change the plugs? Those surface gap ones seem to die a lot quicker than a conventional type.
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Old 18 July 2013, 06:16   #6
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Hi

I have two motors and the other one is knackered and just my luck with this weather that my boating grinds to a complete hault

Thanks for the replies that's a relief if its a cooling hose

New plugs have been fitted and all sparking good, compression good on all cylinders

Problem remains, it will not start unless throttle is at least half open and as soon as its reduced to idle it cuts out also it seems shake a bit more than it used to but not sure if its me looking for problems

There is an an oily residue coming from the exhaust when running with the muffs on and I now have a stain on my driveway and although I thought it would be milky its black.

Also the plugs on 1&2 cylinders remain clean but 3 is black oily every time its removed.
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Old 19 July 2013, 11:02   #7
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Quote:
Originally Posted by swesandy View Post
Hi

I have two motors and the other one is knackered and just my luck with this weather that my boating grinds to a complete hault.
I know the feeling well......

Quote:
Originally Posted by swesandy View Post
New plugs have been fitted and all sparking good, compression good on all cylinders.
Visual or with a spark tester? A visible spark is one thing, one to properly ignite the contents of the cyl is a whole different discussion. - Do a physical check of the leads & the LV connections too.



Quote:
Originally Posted by swesandy View Post
Problem remains, it will not start unless throttle is at least half open and as soon as its reduced to idle it cuts out also it seems shake a bit more than it used to but not sure if its me looking for problems.
Mine starts better on choke & no throttle. You had the carbs off to clean them - did the idle mix screws (the ones on the front you get at through the air box) go back exactly where they came out? Cleaning it may have upset the previous balance - idle mix is incredibly sensitive to those adjusters.

(and did you adjust it on muffs? - the back pressure on the exhaust when afloat will kill it dead if so - always adjust in the boat on the water - or a bin filled to the level it sits at when afloat)



Quote:
Originally Posted by swesandy View Post
There is an an oily residue coming from the exhaust when running with the muffs on and I now have a stain on my driveway and although I thought it would be milky its black.
It's a premix 2- stroke- that's normal!

Joking aside, if it's actually dripping unburnt oil and it's shaking that would hint at least one cyl isn't burning.... Either that or there is residue for beforehand or it's running so rich that's why it stalls (back pressure comment above still stands)


Quote:
Originally Posted by swesandy View Post
Also the plugs on 1&2 cylinders remain clean but 3 is black oily every time its removed.
What you calling 1? - top or bottom? Remember the twin carb - Mid cyl gets a 50/50 from each carb - is the middle one exactly as clean as "#1"? If so then the carbs are presumably reasonably matched.

No idea if yours has the mod or not but the top carb has a slighty bigger main jet - if you had them apart I assume the jets went back into the carb they came out of?

If you've had a puddle of oil in the crankcase, the bottom cyl usually gets it, and if you haven't been running hard it will likely have just glooped itself round the cyl.


Are your CCV hoses all OK, still connected to the air box & not blocked?
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