I have a 2003 Yamaha 90 hp 3 cylinder. In order to get the engine to start I have to take the engine cover off and move the emergency start switch from the normal position to the emergency position. Once the engine is warm I can move it back to the normal position and the engine runs fine and starts fine from the normal position for the rest of the day, just not on the initial start. I removed the carbs and gas filter and and cleaned them, I replaced the spark plugs and also the fuel/water separator but still the same problem, any ideas what to try next?
same motor as mine. pump primer bulb until hard, neutral throttle in closed position, press key in while turning to activate the prime start enrichening device on front of center carb. if prime start is working correctly it should feel warm/hot to the touch on top when activated. I usually crank on motor for a second or two, stop and wait a moment, then crank and she fires right up. you can experiment with slightly different combinations on your starting proceedure. the red switch should be in the "normal' position if everything else is right. My motor always seems to start better when there's a good fresh charge on the battery-guess it just spins the motor over faster. Hope this helps and good luck!
pushing the key in on cold start actuates the prime start enrichening device on the middle carb, allowing for much easier starts when motor is cold. after motor is warmed up no need to push key in to start. prime start is just similar to the choke on many other motors. try that and hopefully she'll crank up good for you. Good Luck!
The Yamaha prime start enrichment System does not require you to do anything to make it work.
The system works by itself and is always active unless you turn it off manually by the red lever.
The two wires are Black to ground and the blue connects to the wire coming off of the regulator which feeds voltage to the unit while the motor is running, heating it up ,expanding the wax pellet and extending the needle closing off the passage stopping the extra fuel from flowing. as long as it is warmed up there is no fuel flow through it.
Pushing the key in does not have anything to do with this system from what I have read in the manuals, that (Pushing the key) was the way the old electric chokes worked in the past to close the butterflies and it was the way my old 35 HP Johnson worked by squirting fuel into the carb, with a electric solenoid but it is not needed for the Yamaha system.
If you know how pushing in on the key helps please enlighten us with that information
my impression is that pushing the key in activates the prime start feature. if it doesn't then what does pushing the key in do? All these years and my motor starts right up cold and i've never moved that red emergency switch. Hope we can get some clarification on this because one of us has to be wrong. maybe Rodbolt or one of the other guru's could offer their take on this subject. this is how we learn. Good Luck!
I believe the problem is in the prime start enrichment system if the motor starts and runs fine except for cold starting and he is not pulling up on the idle lever while trying to start.
One thing I do not know is if the pump diaphragm is bad on the prime start system will the emergency position still work, or will the emergency position only work if the thermovalve is plugged and will not let any fuel through its passage way. Maybe this is something others can answer.
Last edited by 99yam40 : September 1st, 2009 at 06:49 PM.
Reason: add comments
so the prime start is always ready to enrichen the mixture if it senses that the engine is cold, but if the engine is warm then prime start will detect that and not enrichen the mixture? so the magic in the system is that wax pellet, it's totally automatic and pressing in on the starter switch really does nothing? I have a Yamaha manual and an operators handbook and I really want to understand this.
My operators manual says to turn the key to start for no more than 5 seconds and then let sit for 10 sec if it did not start, and then repeat. It says nothing about pushing on the key.
I guess that push-in ignition switch on my motor is just something left over from another model with a key-activated choke. and all these years I've been pushing on that switch and may as well have been peeing off the dock! well it's never too late to learn something. someday when I've got some spare time I may just disassemble that prime start just to see how it works on the inside, because it's still a mystery to me. Good Luck!
Had the same problem w/ my 1999 90hp tlrx, the hole time it was water in the carbs and plugged jets, and yes I have a water fuel seperator, now it runs great, even though I tore them down three times, and pushing the key in does nothing, the prime start enrichment is all electronic. mine starts in -10,20deg just fine, cranking the key.
Glad you got it running and in the process learned a lot more about your motor. I know that I continue to learn from these forums. Beats the heck out of going to the boat dealer$$ with every little problem. Good Luck!
I have a 2003 90TLRB. It too doesn't not require the ignition to be pushed in. It'a all automatic. I have to keep that in mind not to confuse it with my 40 hp Force that needs the switch pushed to choke the engine (or squirt a bit of gas into the carb).
__________________ Carl
Carolina Skiff 175 Sea Chaser, 90hp Yamaha 2-stroke
River City Marine 14' AL flat-bottom, 40hp Force 2-stroke
Yamaha 90: Hard to start
Re: Yamaha 90: Hard to start
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