2 stroke Outboard struggles in cold weather?

CAnderson

CAnderson

Well-known member
I have a 1996 Mercury Seapro 40hp, 2-stroke tiller outboard on my MV john boat. The engine runs good under normal conditions. I say that with the caveat that it runs at a high idle and reverse gear slips. I know it is not a perfect engine, but it serves me very well and has always reliable gotten me there and back.


A couple of times, I have started the engine up when the temps are usually around 30 degrees and she struggles a little. The engine really only wants to run at an idle speed even at WOT. I am thinking it is just taking a longer time to warm up and is more of a fuel delivery problem with everything being so cold.

Can anyone confirm or deny those suspicions? If you need more info, please ask and I will provide as much of that as possible.

Thanks in advance.

Chad
 
Not sure this is an apples to apples comparison but I had the same trouble with a 1995 3 HP Johnson. It was the choke.
 
It used to happen to me as well. The carb is just cold. Let it warm up a little more before you head out. At the end of the day I would to disconnect the fuel line and run the motor empty. This way you have no oil in the carb ( the oil gets pretty thick in the carb and kind of gums up the ports.). This solved my problem hope it does yours.
 
Thanks guys. I will look to clean the carb down a little and give her more time to warm up before heading out from the ramp.

chad
 
Chad - I can't speak to two strokes but, my 4 stroke Nissan is infallible in cold weather. Fuel injection goes a long way... Pat
 
chad I would clean the carbs ,then make sure you are using sea foam in gas that helps plus you should run a little more rich in the cold let it warm up good
 
Thanks Rich. I have been using Startron (I think that is what it is called, blue liquid in a clear plastic bottle with a long neck). I will look into the SeaFoam. I would suspect I could pick that up at the local marine dealer or West Marine. Any chance they might have that at NAPA, AutoZone or even Walmart for that matter?

Chad
 
Make sure the gas is fresh. I have a 25 merc on my North Dakota boat, starting fluid has been my savior many a dark cold morning. I more often than not lose track of how old the gas is. One year I couldn't make any speed without the choke half out, I thought this was going to ruin my walleye trip, as the nearest outboard shops are 60 miles or so away. By chance I thougt I would try fresh gas, ran like new! Rich
 
Thanks Rich. I have been using Startron (I think that is what it is called, blue liquid in a clear plastic bottle with a long neck). I will look into the SeaFoam. I would suspect I could pick that up at the local marine dealer or West Marine. Any chance they might have that at NAPA, AutoZone or even Walmart for that matter?

Chad
Click to expand...

Seafoam is available at all those places, also use the highest quality NON-ETHENOL gas you can get like BP Ultimate or something of that nature.
 
I am a big believer in running sea foam through my small engine a couple of times a year. also, unfortunately, you can't get non-ethanol gas in NJ. You might also look at the thermostat, it generally is an inexpensive and easy to change part. But you probably just have a gummy carb.
 
Outboards are factory jetted for moderate temperatures as most folks use them spring through fall. What happens when you run a motor jetted for seventy degrees in twenty degree weather is it runs lean, more o2 to fuel, (cold dry air (winter) is more dense than warm moist air (summer)this is why your motor sputters and is weak it's starved for gas. It runs well choked because you are limiting the amount of o2 getting to the combustion chamber and giving the correct fuel to o2 ratio. The smaller the motor the more pronunced the problem (around 20 degrees I can barely keep my 2.5 running). There is no question fresh fuel is important but will not solve the issue.
 
What Jason Williams just explained is what happened to my 1976, 9.9 Johnson in North Dakota. I had to run it with the choke half out. Brought it back to Florida,its fine. Oh yeah! Its for sale...
 
Starting fluid has always worked for me on the really cold days. Also check your chock pull. Some time there set in stages. Where you feel it click and you think its full chock but it still has another stage to pull out.

With the starting fluid you don't want to over do it. A little shot is all I needed in each carb. Once she turned over and warmed up she was good for the day.

Also run the fuel out and you might want to invest in an inline fuel filter. Ethenol sucks.

Phil
 
It is really not a starting issue. It is an issue of propelling the boat at speed. The engine is electric start. It starts fine and idles fine, albeit a bit high. but it starts reliably.

I will check the carb today and try to flush the engine from the saltwater on our most recent hunt.

I don't have any kind of choke setting to adjust on the carb. It handles that itself, which I assume is a vacuum deal, but haven't really paid much attention to how it operates.

Ethanol does suck and fortunately I installed a few years ago when I bought the engine. I saw firsthand what old ethanol fuel did to a friend's much newer Yamaha outboard. Paying someone to clean your 3 carb system looked to be cost prohibitive to me. Glad I have enough know how to work on my own engines.

Chad
 
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