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

[Carl Wonderful]

Hello,

New to Outboards and don't want to do something dumb. This motor was said to still run good. But hasn't been run for 5 years. What are the first steps and what not to do? 1973 (ish) Mercury 4hp outboard. Came with my 1971 Catalina 22.

I know I need to get good gas...
1. But do I have to drain any old gas inside?
2. Think mix is supposed to be 50:1.... what kind oil do I buy?
3. What kind of gas? Ethanol free? premium or anything from the gas station?

I have a barrel I can fill with water to run it in.

4. Any risk to damage it...should I test to see if its not "seized"..
5. I see lot people taking spark plug off and spraying some kind oil into it. Necessary? If so what kind oil?
6. Should I loosen the bottom "gear" oil nut to see if the oil is black/creamy/clear/ or even empty?
7. its definitely a 2 cylinder, right?

Any other info greatly appreciated. I basically know nothing so clear and specific steps and products would be great!!!

 

[shemandr]

Yes new gas.
No, don't save the old.
2 cycle oil is OK. I wouldn't spend on premium brands until it runs.
Ethanol free if it's available.
You can tell pretty fast if it's seized.
Marvel Mystery Oil is a good choice to squirt into the cylinders prior to starting. Pull the start cord to distribute.
Replace the lower unit lubricant if the motor coughs twice while trying to start.
Yes, 2 cylinder.
You'll prolly need to rebuild the carb before it will run. For sure disassemble and clean. Once you do that you might as well do the rebuild.
Add a fuel filter and make sure all fuel connections are tight.
Maybe it will run.

 

[dlochner]

In addition to @shemandr's suggestions:

Change the water pump impeller. It has likely taken a set and will not pump a sufficient volume of water to cool the engine.

Put a new properly gapped spark plug in it.

Definitely use ethanol free gas if available, if it's not, drain the carb after running the engine and drain the internal fuel tank.

 

[Rich Stidger]

Ordinary gas with 10% ethanol is ok for now, but after you get it running switch to ethanol free if you want trouble-free running. Ethanol will trash the carbs on these small engines in less than a boating season.

 

[marcham]

Honestly, I'd just buy a new carb.

If you don't want to buy a new carb, take it apart and clean it before you do anything else.Might want to consider replacing the fuel hoses, as they may be clogged....

Sometimes you get them started, then a little piece of crap goes and blocks the jets, then it runs worst....

 

[Project_Mayhem]

You might have some luck by draining the bowl, filling it with carb cleaner and giving it a few pulls to flush the carb out. I had a mechanica do that to get my 140hp two stroke running again. Next step after that would be a carb rebuild. Take it step by step so you don't dump too much money into something that's not going to run right

 

[Indysailor]

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.

 

[Rich Stidger]

For engines under 10hp, carb disassembly and soaking in carb cleaner works well. If you have access to an ultrasonic cleaner, put the carb parts and cleaner in it and process. For 4-cycle engines, use of an ultrasonic cleaner is essentially required due to the much smaller passages in the carb vs a 2-cycle engine. Since you have a 2-cycle engine, you can probably get by with just an overnight soak.
But once clean and running, only use E0 gas.

 

[BigEasy]

Might be difficult to find a new carb of that vintage; however, a rebuild kit should be available. Agree with others; remove bowl & clean, empty tank & replace with fresh fuel / oil mixture, & fuel filter (if one is present). Check spark plug fire. If you have spark & it won’t start, time to disassemble carb & clean with carb & choke cleaner. Would be great if you have access to an ultrasonic cleaner. (check harbor freight). If it was stored with ethanol gas, the Carb is likely corroded beyond repair. If you get it running, as others have mentioned, install new water pump impeller, lower unit oil, fuel hoses , fuel filter, & a new spark plug. If no luck, perhaps an outboard mechanic can get it going. Surprisingly there are quite a few of these vintage outboards that are still running. I once had a 50 hp Mercury outboard that would start but not rev to normal rpm’s if it sat unused longer than 4-6 months. Carbs would get gummed up & this was before ethanol. Best of luck.