I have just acquired the subject outboard motor and have been getting it into running condition. The rope start mechanism was seized so I had to dismantel and clean that up. The shifter (tiller type) and throttle linkage were also seized and I got those all cleaned up and working. The next problem was the carb.
The carb was even difficult to dismantel, but I did it. Only damaged one part and that was the needle valve. Fortunately for me, the needle valve is about the only part left available for that carb from Mercury. So I managed to get it all cleaned out and re-assembled to find out that the accelerator pump diaphragm was leaking. *^%#$@!! It took a couple of weeks to find the part, but a very helpful Mercury dealer found one. At least, found a source for just about all the carb parts. That would be from Yamaha, the builders of the motor.
Anyway, got the carb all assembled and put back on. Pumped up the gas, and low and behold the motor started on the very first pull. WOOHOO! Had to adjust the idle speed a little but other than that it was great. Thing just idled beautifully. But! After leaving it to idle for a couple of minutes, the idle rpm started to slowly climb. After another couple of minutes the idle rpm had climbed probably 400-500 rpm. I assumed that it was just a matter of getting all the gunk cleaned out (the outboard had even been transported laying down tiller side up - oops). I adjusted the idle speed back down again and it was running . . .ok. The idle wasn't as smooth as it was initially, but it was acceptable. Even stopped smoking, which I assumed was due to being lain down on the wrong side.
Here is where the trouble starts. I decided it was time to test the two kill switches to make sure they worked. I hit the button in the end of the tiller and the motor stopped. Kool. Now just start it back up and test the other switch. But I could not get that mofo to start again to save my life. I tried everything I could think of but it just would not even fire any more.
The next morning I go out there to "play" with it some more. Just thought I'd give it a couple of pulls just to see what would happen. I backed out the idle speed screw a couple of turns just in case. Second pull that thing is running again. What the . . .?!?!? But once again the idle speed started to climb after a couple of minutes and a couple of minutes after that it was 400-500 rpm too high again.
The bottom line is that it seems like you get one start per day with this motor. If you get it started and let it run for any length of time, it won't start again the rest of the day. I have even gone out there 4 or 5 hours later and it still wont start. But if I wait til the next morning. . .pull,pull,prrrrrr.
So does anyone have any ideas what could be causing this? As others have mentioned, there isn't much in the way of adjustments on that carb. One air adjustment on the top seems to be about all. And the problems don't start until the motor starts getting warm. If you use this motor to cruise out to your favorite fishin hole, you'd better be prepared to spend the night.
Thanks in Advance and sorry I took so long,
xeddog
The carb was even difficult to dismantel, but I did it. Only damaged one part and that was the needle valve. Fortunately for me, the needle valve is about the only part left available for that carb from Mercury. So I managed to get it all cleaned out and re-assembled to find out that the accelerator pump diaphragm was leaking. *^%#$@!! It took a couple of weeks to find the part, but a very helpful Mercury dealer found one. At least, found a source for just about all the carb parts. That would be from Yamaha, the builders of the motor.
Anyway, got the carb all assembled and put back on. Pumped up the gas, and low and behold the motor started on the very first pull. WOOHOO! Had to adjust the idle speed a little but other than that it was great. Thing just idled beautifully. But! After leaving it to idle for a couple of minutes, the idle rpm started to slowly climb. After another couple of minutes the idle rpm had climbed probably 400-500 rpm. I assumed that it was just a matter of getting all the gunk cleaned out (the outboard had even been transported laying down tiller side up - oops). I adjusted the idle speed back down again and it was running . . .ok. The idle wasn't as smooth as it was initially, but it was acceptable. Even stopped smoking, which I assumed was due to being lain down on the wrong side.
Here is where the trouble starts. I decided it was time to test the two kill switches to make sure they worked. I hit the button in the end of the tiller and the motor stopped. Kool. Now just start it back up and test the other switch. But I could not get that mofo to start again to save my life. I tried everything I could think of but it just would not even fire any more.
The next morning I go out there to "play" with it some more. Just thought I'd give it a couple of pulls just to see what would happen. I backed out the idle speed screw a couple of turns just in case. Second pull that thing is running again. What the . . .?!?!? But once again the idle speed started to climb after a couple of minutes and a couple of minutes after that it was 400-500 rpm too high again.
The bottom line is that it seems like you get one start per day with this motor. If you get it started and let it run for any length of time, it won't start again the rest of the day. I have even gone out there 4 or 5 hours later and it still wont start. But if I wait til the next morning. . .pull,pull,prrrrrr.
So does anyone have any ideas what could be causing this? As others have mentioned, there isn't much in the way of adjustments on that carb. One air adjustment on the top seems to be about all. And the problems don't start until the motor starts getting warm. If you use this motor to cruise out to your favorite fishin hole, you'd better be prepared to spend the night.
Thanks in Advance and sorry I took so long,
xeddog