mercury outboard wont start

[bimini blue]

so this is a bad on me, we cruised in June got back at the end of the month
the dinghy outboard went on the stern pulpit,
it is now December and I have not cranked it in at least a couple of months and of course it wont start

any tips
do I put a little ether or starting fluid
clean the plug
would rather not have the mechanic come out

thoughts

[thomm225]

If you put ethanol gas in it back then, was it treated?

If not, your carburetor may need cleaning.

If it's an old two stroke, you may need to clean or replace the plug

If it has an external/internal tank switch, is the switch in the right position

[CapnSparky]

I had a similar issue with an older 5 hp Mercury. It would be running fine and then just stop for no reason. I'd crank on it until I'd get fed up and stop. An intermittent problem and what I ultimately found was a small hole in the bottom of the rubber boot on the "kill" switch which allowed moisture into the switch contacts causing it to short out (I guess). Anyway, about drove me nuts until I found it and thought I'd share it with you. Good luck!

[a64pilot]

Try putting a rag over the carb when you pull the rope, that will force fuel into it, don’t do it too much or it will flood of course. Then if it runs for a sec and then quits, it’s most likely the carburetor.
If it won’t even try to run, see if it has spark, if it’s a weak spark try a new plug before you tear into the electrical system.

[thomm225]

Originally Posted by a64pilot

Try putting a rag over the carb when you pull the rope, that will force fuel into it, don’t do it too much or it will flood of course.

Or you can use the choke to get the same result......no rag needed.

[thomm225]

What year and size is your Mercury?

I have a 2011 Mercury 5 HP 4 Stroke Outboard, and it's the main engine on my sailboat

[bimini blue]

thanks all , I think the spark plug is fouled and I need a new one? or clean it
I can smell the gas and it is not ethanol

it is a 6hp four stroke, essentially a tohatsu with an intregal tank

would the plug and some starting fluid do the trick?

[thomm225]

Originally Posted by bimini blue

thanks all , I think the spark plug is fouled and I need a new one? or clean it
I can smell the gas and it is not ethanol

it is a 6hp four stroke, essentially a tohatsu with an intregal tank

would the plug and some starting fluid do the trick?

If the plug is fouled, clean it, but usually plugs don't get fouled on 4 strokes. (and check the gap also)

I replaced my plug after 4 years of use ...maybe 5.

You shouldn't need starting fluid

Sometimes it's best to hookup the external tank, change the switch, and pump up the bulb on the fuel line until tight. That will really get the gas up there. When my engine won't start from the integral tank, it will from the external

Also make sure you cutoff switch is open

[mario f]

That long with fuel in the carb I would think that gas is turning into shalack (sp), and jets plugged, bowl needle etc. Take appart and clean carb, gas tank and clean fresh fuel-With NO Ethanol !!!
If you have to pay some one to do it and watch and learn, believe me if I can do it anyone can.

Good Luck

[a64pilot]

Starting fluid isn’t needed, and if incorrectly used can cause damage.
Starting fluid was for way back when for Diesels without glow plugs, in cold weather.
Most often chokes don’t block off the intake completely and you can’t pull the strong vacuum you can with a rag.
Cleaning plugs often doesn’t work, they sometimes break down electrically internally and develop a short, and they usually aren’t that expensive, and your motor will likely run better with a new one anyway.

[thomm225]

Originally Posted by mario f

That long with fuel in the carb I would think that gas is turning into shalack (sp), and jets plugged, bowl needle etc. Take appart and clean carb, gas tank and clean fresh fuel-With NO Ethanol !!!
If you have to pay some one to do it and watch and learn, believe me if I can do it anyone can.

Good Luck

Ethanol will work fine (it's what the engine was built to use), but if you plan not start the engine for a few months, you need to use stabilizer in the fuel and run the engine out of fuel when shutting down

I treat my ethanol fuel in October and use what remains in the tanks in the Spring, and I do start my engine every couple weeks all Winter

[thinwater]

That's a long time for gas in a small tank. There could well have been evaporation of volatiles, and there could be a few drops of water in either/both the tank or carb bowl. I would certainly dump it out and start fresh.

Cleaning the plug is a few minutes. You should have a fresh on on-board at all times, and keep the wrench with it. Also a shear pin, filter, and starter cord.

Filter is cheap and fast. It's probably due.

Then it comes down to either a clogged passage (not hard to clean--I know you don't want to, but you should learn how), or ignition problem (probably over your head). Basically, all of the above advice offered was sound.

Biobor EB and Merc Quick Store are miracle workers regarding fuel stability, carb corrosion, and clogging (I've done lab and field testing of most). Many are snake oil. Use one of these EVERY time. I have for ~ 7 years, and in the process, forgot much of what I used to need to know about carb cleaning!! I knew a lot about cleaning carbs before. (There are 3 outboards on the PDQ alone).


A few fuel tips: http://sail-delmarva.blogspot.com/2017/05/100-best-buys-chapter-3.html

[winschwab]

I have a 2015 3.5 and a 2016 6.0 Tohatsu. I run non-ethanol with Stabil and still have lots of trouble. Often hard to start, but not consistently. Often acting starved for fuel: will only run with choke half way out. I have disassembled and reassembled the carb re manual instructions, but I'm not sure I'm really getting at the problem. Any more suggestions?

[Var Korall]

If laid on the wrong side, even for a short period, some mercury 4 strokes will allow crankcase oil to enter carb bowl and/or cylinder (which can cause hydraulic lock) If just in the carb, of course the engine will not start, but it will turn over. Did you possibly lay the motor down before transferring to pulpit?

[FULLCIRCLE331]

I have a Mercedes 3.5. I always run it out of fuel to shut it down. It is hard to start if I leave fuel in the carb.
I have two other problems once after three months storage it wouldn’t start even with conditioner there was water it the tank and carb. Took apart the carb and drain the fuel all was fine. The other time it just died while running and would not restart. That was the spark plug.
I use acetone as a starter fluid a few drops in the carb, if it starts it is a fuel problem if not it’s electrical. Only a few drops of acetone and don’t run for more than a few seconds it can damage the engine.