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Outboard service?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.


Can anyone give me some advise on what kind of service I should do on a Mercury 4hp (2 stroke) outboard that has been sat for a year.

New plug for sure, but anything else/instructions recommended?

If you ran it dry of fuel the last time it was used, it probably doesn't need anything. If not, the carb is probably gummed up, usually fairly easy to rebuild. If it wasn't stored upright, the carb may still need work. Plugs should not need more than a brush off. After it starts, Check to see that the water pump (if it has one) is working.

Good luck

make sure you drain the old gas out "if any is left in the tank" and rince out good with some fresh gas and change out the inline fuel filter. If doesn't have one add one! Gas goes bad faster than you think and it turns to varnish if sits in the carbs for long time and will block up the carb jets!

Check that the water squirting out of the engine is strong enough. If not, you're going to have to replace the impeller. It has a nasty habit of curling up when left standing for a long time.

Cheers Folks

Am going to have a go at it next week I think.
I just know it is not going to be a straight forward job!:confused: !

wish me luck!:duh
Miles, that is good advice, but even if its squirting well you should replace the impeller if its 3 years old. The rubber gets brittle with age and will disintegrate quickly. You can leave the dock with a good indication stream and become stranded because it fell apart.
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changing the lower unit oil is usually a once-a-year thing as well. Although I'm scratching my head right now trying to remember if something as small as a 4hp even has lower unit oil, probably not. Also, just to put it out there, one of the best ways to maintain it in "like new" condition is to take the cover off and spray it all down with a waterproofing lubricant like WD40 periodically, keeps it all from corroding on you.
what year was the outboard made?most older ones dont have a tell tale and 4hp lower units do require oil there should be a drain plug on the lower unit,there shouldnt be any water in the oil when it comes out
im not sure if this has been said yet cause i havent read all the replies yet, but if the engine isnt starting at all, one thing to check is if the plugs are even sparking. Just unscrew one and lean it against the head next to its screw hole. Try starting the engine(key or pull start). You can see and hear it sparking if it is working. if not then its a deeper electric prob.
Not sure of the year? no markings to speak of to distinguish it.

Not got round to doing it yet!

Like all best laid plans eh!? :D

Off up to Skye for a 4 day jolly in September with some mates so best pull my finger out!!
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