What to do first? Sat for 5 years. Old Mercury 4hp Outboard motor

[Carl Wonderful]

Pull the spark plug ( get a replacement) and pour some oil down into the cylinder and let it sit for 24 hrs. Pull on the starter cable slowly to see if it turns or if the piston rings are stuck to the cylinder wall. If stuck get some penetrating oil and repeat the flush. Once the engine is turning test for an ignition spark. Once you confirm you have a spark remove the carburetor and rebuild or replace. (they get gummed up and the seals deteriorate). Empty the old gas can and make sure is clean and add new gas with 2 stroke oil at 50:1. If the engine shows compression and you have a timed spark with fuel it should start. Adjust the carburetor and idle speed and you should be good to go.

Thanks for the clear instructions. Couple questions about specifics...sorry I'm new to all this...

1. What kind of oil to pour down the cylinder?
2. Any idea where I would find a kit to rebuild the carburetor?
3. How do I adjust the carburetor?..
4. Does it need a specific spark plug?

I have the gas/oil mix and just ordered a compression tester.

Thanks for the help.!!

 

[dLj]

Thanks for the clear instructions. Couple questions about specifics...sorry I'm new to all this...

1. What kind of oil to pour down the cylinder?
2. Any idea where I would find a kit to rebuild the carburetor?
3. How do I adjust the carburetor?..
4. Does it need a specific spark plug?

I have the gas/oil mix and just ordered a compression tester.

Thanks for the help.!!

1. What kind of oil to pour down the cylinder? - Marvel Mystery oil is one of many that would work

No idea about #2

#3 - I'd have to see your carburetor - still might not know but I have worked on a lot of old carbureted engines...

4. Does it need a specific spark plug? - Just match the one that you take out. There should be a designation on the side. Could be an old number but it's usually easy to find a modern equivalent.

When you get that baby running - you better post a video with sound! Hahaha

dj

 

[MaryEllaRose]

Beware of carbs bought on Amazon. I bought one for my Tohatsu 9.8 and although it looked identical it was jetted so rich it carbon fouled the plugs in only a couple of minutes, filled the garage with black smoke. Amazon only gave me a partial refund because gas had been run through it.
Clean the carb, especially the small idle jet, use fresh gas with proper oil mix ratio and fresh plugs and try it. I’m willing to bet that 50+ year old Merc will fire right up.

 

[Carl Wonderful]

2 cycle engines are remarkably capable of sitting for a long time and firing right up. I'd leave it in neutral, drain the carb bowl, use new fuel, new plug, see if it fires up. Have a can of ether on hand to cough it to life. If it doesn't start, soak the carb, clean the jets, repeat. Or as suggested, just buy a new carb.

Sorry I' such a noob....
How do I drain the carb bowl?
How do I know which plug to get?

 

[dlochner]

Sorry I' such a noob....
How do I drain the carb bowl?
How do I know which plug to get?

At the bottom of the bowl there should be a little drain screw.

There are several ways to know which plug to buy, it should be in the manual, it may be on a sticker on the engine or inside the cover, and it it printed on the plug. Auto parts stores will have a cross reference chart for the different brands.

 

[Indysailor]

Sorry I' such a noob....
How do I drain the carb bowl?
How do I know which plug to get?

No need to apologize. You should be able to find the right plug through a bit of internetting, and there will likely be brand and identification markings on the ceramic part. The bowl is at the bottom of the carburetor and you'll probably see a small slotted screw on it. You shouldn't need to back it all the way out to drain it and it may be dry after all these years anyway, which is why others are rightly suggesting it may be gummed up with what's left when gasoline sits over a long period.

 

[rgranger]

How do I know which plug to get?

 

[BigEasy]

How do I drain the carb bowl?

Usually there are two screws in the carb bowl. One is a drain screw that is located at the interface of the bottom & side of the bowl. Good for draining fuel if you suspect water or contaminates. The other screw is located mid center on bottom of bowl and attaches bowl to the carb. In your case, I would remove the bowl & clean it. There will be a rubber or fiber gasket between the bowl & carb and between the screw & outside of bowl; inspect them for integrity. While the bowl is off, spray some cleaner into the fuel flow valve that is attached to the hinged end of the float that is housed in the bowl. Gently move the float up & down while spraying the valve that is likely gummed up with old fuel. if you decide to remove the float & valve, take a picture so you’ll know how to reassemble & don’t lose that hinge pin!