Cold Start Issue - or shutdown issue????

Good Morning All,

I currently live in New Zealand and own a 1987 Johnson 70Hp, owned for about three years now. I am more than happy with the motor and have been told by a reputable service centre that it is in very good condition.

I imagine that you guys get asked 100's of questions about starting issues, specifically cold starts and this is another. This is basically a narrative and the symptoms of my problem.

If the boat has been standing a while and I do a periodic run of the motor on my driveway she really struggles to start. She will only start if I use the electric choke and then will only run for a few seconds at high revs and then die. This requires me to repeat the process about 9 or 10 times before she actually takes and settles down into a high rev-high pitch banshee like scream as a result of me playing with the idle lever on the throttle. If I do not do this she will not idle at all. After a few seconds I can then bring it back down and return some sense of normality to the street. (By now most of the neighbors have come out to see what plague has befallen our community). I can then let her run for 7 or 8 minutes during which she purrs like a kitten. If I try and start her the following day or within a week or so she behaves beautifully.

Now here is some further information. I am a rather proficient motorcycle mechanic and have rebuilt many two stroke engines and carburettors in my time so I decided to open up the carbs one morning and see if I could see anything amiss, and just how close to a motorcycle carb these things were. To my dismay I didn't find anything wrong at all. Everything was, according to the manual, exactly as it should be. Tolerances were checked, needles and seats inspected, float levels verified etc etc etc. Needless to say everything received a good clean with compressed air and was reassembled clean and......wait for it.... DRY!!!!!!

I then tried to start the motor after pumping the bowls full (bearing in mind that the carbs were DRY!!!) and the motor started first turn of the key, settled into idle immediately and didn't miss a beat. No choke required. No fast idle lever required. No foul language. No disturbed neighbors and no missing dogs, like after Guy Fawkes.

So here is my take on the issue.

When I shut down the motor after being out on the water or running it on the hose on the driveway, some fuel/oil mix is left in the carburettor bowls which as time passes loses it's fuel component until only gooey oil is left in the carburettors possibly interfering with the idle jets, something which gets diluted after a few starting attempts and the use of a choke/fast idle lever. Anyone agree on this????

When I dried out the carbs/jets there was no gooey oil left and as such she started first time. Am I on the right track???

Is there something I am doing wrong when I shut down the motor after use or a step I am missing? I have tried shutting off the fuel supply and letting the motor die naturally from lack of fuel but was told that this is not a good idea.

Can anyone please supply me with some constructive ideas or point me in the right direction. Stripping the carbs and blowing then dry after each use is not an option for me.

Thanks in advance for your thoughts.

If your motor sits for more than a day you need to do the cold start procedure. Pump the primer ball till hard raise the fast idle lever until you feel a little resistance no need to push it as far as it goes. Turn the key on push the primer in and start hold the primer in for a couple of seconds while it's running. In your driveway you don't want to be above 1500 rpm. Couple things if you tilt the motor up the carbs drain out that is one cause and the carbs are not sealed they vent to the atmosphere so evaporation has an effect. I have the same motor 1986 70 hp that is how it has to be started. The only time I don't pump the ball is if I am fishing and the motor sits for a couple of hrs. But I still have to prime it and use the fast idle lever to restart it next morning starts all over again. Don't run it out of fuel if the vro is connected because the oil side of the pump keeps pumping and will fill the carb bowls.

Running the carburetors dry is a very good practice and keeps them clean.-------Have you verified that the electric fuel primer works when you push in the key ?--------Do you push the key in while cranking it over ?--------Do you push the key in momentarily when motor falters after start up ?