SOLVING An Outboard Cold Start Issue!

Will McQueen, I've got a 2002 Honda-90 horsepower carbureated four-stroke

Those things can always be very temperamental being a carbureted four-stroke, but that runs great during the summer and never have an issue starting during the hotter months

When it gets cold this time of year, I always winterize it because it's a pain to start in this colder weather

I've always wondered if I am doing something wrong at the ramp when it's colder

or maybe it's just the way it is with colder weather and carburetors

Any tips, would love to get a few more weeks for fishing. What I would say is that a couple of different things, yes, it's going to be temperamental

So thinking about what's going on here, one thing that's possible, not saying that this is it

but is that you're still trying to run a summer blend of fuel when it's cold out

And I'll probably get this wrong, but the way I think I remember is you've got RVP

which is the reed vapor pressure or something like that. And that's a rating that's on the fuel

So during the summer, it'll have a lower rating because it's hot out

So it doesn't need to have the same burn ratio. You know, it doesn't need to be higher

It doesn't need to have help burning because it's hot outside. But when it's cold outside, what they'll do is most gasoline companies, they will add, I think

it butane to the fuel And they call it a winter blend which allows the fuel to burn at a higher pressure I believe And like I said I not an expert on fuel and the chemical makeup of gasoline

but this is the kind of the way I understand it, and the way I think I remember it being that summer months have a low number of RVP

winter months have a high number of RVP, and that is because they want the fuel to be able to burn easier

in the colder winter month. Now, if you're trying to burn a summer blend in the winter when it's cold outside

then your engine's going to have trouble running. It's going to have a hard starting

and it's not going to burn the way you really want it to

especially on a carbureted four-stroke. So a carbureated four-stroke has, you know, TPSs and the ignition is based on a lot of other factors

but it's still using a carburetor. And when you think about, you know, the winter and cold air, cold air is denser than hot air

And the way a carburetor works is it uses a Venturi effect in order to atomize the fuel in the air

So basically, it's using like a vacuum almost and it's sucking fuel up when it sucks that up through your jets and all the other things inside the carburetor

It atomizes the fuel before it sends it into the cylinder. So if the air is denser it going to require more fuel to get that fuel to atomize with that denser air than it would in the summer when the air is thinner I might not be 100 on that because I not a I not a doctor

but what I would say is that the way I understand it, like a carburetor in the colder weather

usually it'll use the thermostat and it'll say, oh, hey, it's colder outside. So it will do

like a warm up. And for like three minutes or however long it may be, the engine will go into a

warm up mode where it will add more fuel and enriching your fuel mixture in order to combat

this and just in colder weather, that's kind of how it goes. So with your enrichiner and it being

colder outside, so on that 90, I don't know how many, on a 2002 90 horsepower Honda, I'm not a

Honda expert. I don't know how many carburetors are on that engine, but my guess is that it's probably

somewhere around three, maybe four carburetors on that setup. I don't know if that 90 is a three

cylinder or four cylinder. But my guess is there's an enrichiner on two of the carburetors and the other two

don't have an enricher. And so you know, you're getting enriched in fuel and two of the cylinders

but two cylinders is not getting enriching. And that's just kind of a cold startup. That's just what

it is until the engine heats up and gets to operating temp. It's going to run rougher because it's

carbureted and because it a carbureted four stroke that just kind of how it is Those are the only two things that I can think about that going to affect that as far as colder weather and a carbureted engine where EFIs they don have that problem You know you got fuel injection And so the computer is reading

the atmospheric pressure and the barrow. It's reading the manifold pressure, which is the air pressure

inside of the manifold. And then it is calculating based on a preset table of numbers on how long

to open the injectors, which it gives it how much fuel gets into the cylinder and how much it

burned. Not an issue with an EFI, and that's why you don't see these, you know, warm up modes and

these cold start issues with an electronic fuel injection four stroke, but you do still see a cold

hard start, rough, idle during cold winter months with a carbureated four stroke, because that's one of

the downsides of a carburetor opposed to electronic fuel injection where everything's already mapped out

makes up for it you know it changes the timing it changes the amount of fuel and everything based on

the temp the the intake air temp because it has a sensor for that so it knows how cold it is

it knows what the atmospheric pressure is inside of the manifold and then it you know the computer

has a table that tells it what to do based on those numbers which

Gets rid of the cold start problem. So if you like this clip, you can watch the full podcast over here

or you can watch another clip over here