Prime start engines

[dark_star]

In order to help all those folks having cold starting difficulty
with their prime start engines, would I be correct in thinking
the biggest factor is pumping the bulb until very firm ?
It seems these engines have to get enough gas in the carbs
to make starting easier.

[alextompkins]

I pump mine until very firm and still can't start the motor. Also have tried pumping throttle several times before starting to no avail.

[boscoe99]

The carburetor bowl needs to be full of gasoline for the Primestart to function correctly. Pumping the primer bulb until it is quite firm does that.

What I don't know and am wondering about is to what ambient air temperatures is a carburetor Primestart designed for. Most folks boat is warmer weather. Where a cold start engine might be at 70 degrees. It is one thing providing enough extra gasoline at 70 degrees but completely different in providing enough at say 30 degrees. My old flying club would not allow the airplanes to be used when the temperatures got below X degrees. It was simply too difficult to get the motors started. There was a chance of a fire occurring if and when a motor was over primed or became flooded.

Thanks goodness for fuel injection.

[dark_star]

I know my F60 starts a lot easier in the summer when the temp is warmer.
It seems the colder it gets, the harder the start.

[99yam40]

I seem to remember a fellow from up in the cold country writing about how he screwed his needle in farther and was able to start his prime start motor in the cold weather.
not sure what motor he was dealing with or if all of these prime start units are adjustable

[pstephens46]

Fuel injection has been a vast improvement along with electronic ignition systems. Cars and boats start immediately. Run pretty good too while stone cold. Cars in the 60's and 70's would sputter and fart for 15 minutes driving along trying to get going. God forbid you would go for a car ride in the mountains at any higher altitude.

[robert graham]

I've started and run my 1999 C90 as low as 28 degrees....just pump the primer bulb until hard and she cranks right up.....let it idle at about 1000 RPM's for several minutes while I get all my other boat gear ready to go. Guess fuel injection on my old 2 stroke would have to be an overall improvement but for now the carbs are fine.....and never give me any problems like plugged injectors...

[panasonic]

The carburetor bowl needs to be full of gasoline for the Primestart to function correctly. Pumping the primer bulb until it is quite firm does that.

What I don't know and am wondering about is to what ambient air temperatures is a carburetor Primestart designed for. Most folks boat is warmer weather. Where a cold start engine might be at 70 degrees. It is one thing providing enough extra gasoline at 70 degrees but completely different in providing enough at say 30 degrees. My old flying club would not allow the airplanes to be used when the temperatures got below X degrees. It was simply too difficult to get the motors started. There was a chance of a fire occurring if and when a motor was over primed or became flooded.

Thanks goodness for fuel injection.

Never had much trouble starting 2 stroke outboards in the cold (70 is a hot day where I am from lol) Snow machines seem to start better when it is -10 to -15...but they are designed for cold weather.

But I can see the four strokes being harder, especially the small pull cord engines, as it is hard to get them to turn over fast enough when all the moving parts and engine oil is cold...

As for the airplanes Bosceo we used to haul all the top plugs out and put them in the toaster oven and pour some Avgas in the oil to thin it out a bit. Put the plugs back in as fast as you can go, get her going, warm it up shut her back down, check the oil make sure all the fuel was gone. And then go freeze to death flying around....great fun.

[mrpontoon]

allso make sure your tilt is all the way down so gas goes in the carb

[99yam40]

allso make sure your tilt is all the way down so gas goes in the carb

why would it not go into the carb if tilted up?
where would the gas go if it was tilted up?

[rodbolt17]

think about it?
where is the float hinged?
what does the fuel in the bowl do as the bowl is tilted?
not hard if ya think about it.
prime start just indicates an auto enrichment. many types.
even EFI motors are listed as prime start.

[99yam40]

Yea I guess the carb would not get as much fuel into it if tilted up, but it would still get some into it, .
Guess the prime start system may not work as well if the fuel level is not completely full

[robert graham]

Double check to ensure that red Primestart lever in in the correct (normal) position.....maybe somebody got to jacking around with it and left it in the "off" position......