The motor is an '86 2 stroke 3 cylinder. When I got it the steering yoke was froze up and the 2 carbs were in a can of carb cleaner. I put a new complete water pump in to start, then freed up the steering - will explain how if anyone wants to know. The motor seemed to run great on the hose in the yard so I took the boat out for a trial. Turns out the top two cylinders are running and bottom cyl is not.
All new plugs. Ran seafoam thru it. New fuel lines. Filter is clean. Rebuilt fuel pump, had a bad diaphragm. The main needle valves in the carbs looked worn to me, I replaced the needle valves and the seats, of course the washer under the seat as well. Sprayed all the little holes out with carb cleaner. More than once. Took the carbs back off and tried to see if there was junk in them. I was careful not to bend/reset the floats.
When I turn each carb upside down and blow into the hose where gas goes in, the valve has it cut off. When I turn it right side up and blow, air flows.
Compression is 99 to 100 in each cylinder. Was a little lower, I sprayed it with oil and let it set a couple days. Checked with no plugs in, spinning it over a few times while watching gauge.
Motor cranks ok, sometimes have to choke it, then runs, but weak. Max at about 2500 rpm on my 18 ft pontoon. If I throttle up it dies.
I have adjusted the low speed screw on both carbs till i got what seemed to be the best performance then backed out 1/2 turn more. I ran it at 2500 rpm in gear in the lake while adjusting. (After doing it on the hose in the yard).
The butterfly in the throat of both carbs is fully open and WOT. It is closed at idle. The motor will run at about 800 - 1000 rpm at idle.
There is a spark on #3 cylinder, I borrowed a spark tester that let me adjust the gap, the best spark I see is about 3/16 inch to 1/4 inch, and blue white. When I make the gap longer I do not think it is making it.
I swapped the #3 spark plug with the #1 spark plug. #1 still works, #3 does not.
#2 plug is black and gummy, almost looked fouled. #1 is a little darkened, some black, tan electrodes. #3 was shiny and brand new looking. Is now getting wet with fuel.
I held a paper towel in front of #3 and #2 one at a time and turned the motor over. The results are the same, I am not getting a lot of spray out of either of them, but can tell there is fuel in there. Stuck a finger in each hole, get a little fuel on the finger and felt like good compression. (Which I checked with the gauge already, about 100).
There is about equal suction on each carb when running. I used my hand to choke each in turn while running at 2500 rpm in the lake, the top one almost killed it, the bottom made it stagger but not as badly.
The bulb in the line pumps up hard, becomes softer when running. New bulb. Put a new gas line from the tank(with a clamp) to the fuel filter on the motor. No quick release fittings at all. Tired of leaks and trying to figure it out.
Bowl on carb is full when I take the bolt out...I cannot think of anything else that might be helpful. Anyone got any ideas? Oh, Last thing, I reconnected the coils up to use the #2 coil to fire the #3 plug and vice versa - moved the wires that drive the coil. It started raining while I was doing that so I did not finish. Did get jolted about 5 times with the spark. It felt like a really good spark but you know how that is.
So. Magic time. Cheap fix is......?
All new plugs. Ran seafoam thru it. New fuel lines. Filter is clean. Rebuilt fuel pump, had a bad diaphragm. The main needle valves in the carbs looked worn to me, I replaced the needle valves and the seats, of course the washer under the seat as well. Sprayed all the little holes out with carb cleaner. More than once. Took the carbs back off and tried to see if there was junk in them. I was careful not to bend/reset the floats.
When I turn each carb upside down and blow into the hose where gas goes in, the valve has it cut off. When I turn it right side up and blow, air flows.
Compression is 99 to 100 in each cylinder. Was a little lower, I sprayed it with oil and let it set a couple days. Checked with no plugs in, spinning it over a few times while watching gauge.
Motor cranks ok, sometimes have to choke it, then runs, but weak. Max at about 2500 rpm on my 18 ft pontoon. If I throttle up it dies.
I have adjusted the low speed screw on both carbs till i got what seemed to be the best performance then backed out 1/2 turn more. I ran it at 2500 rpm in gear in the lake while adjusting. (After doing it on the hose in the yard).
The butterfly in the throat of both carbs is fully open and WOT. It is closed at idle. The motor will run at about 800 - 1000 rpm at idle.
There is a spark on #3 cylinder, I borrowed a spark tester that let me adjust the gap, the best spark I see is about 3/16 inch to 1/4 inch, and blue white. When I make the gap longer I do not think it is making it.
I swapped the #3 spark plug with the #1 spark plug. #1 still works, #3 does not.
#2 plug is black and gummy, almost looked fouled. #1 is a little darkened, some black, tan electrodes. #3 was shiny and brand new looking. Is now getting wet with fuel.
I held a paper towel in front of #3 and #2 one at a time and turned the motor over. The results are the same, I am not getting a lot of spray out of either of them, but can tell there is fuel in there. Stuck a finger in each hole, get a little fuel on the finger and felt like good compression. (Which I checked with the gauge already, about 100).
There is about equal suction on each carb when running. I used my hand to choke each in turn while running at 2500 rpm in the lake, the top one almost killed it, the bottom made it stagger but not as badly.
The bulb in the line pumps up hard, becomes softer when running. New bulb. Put a new gas line from the tank(with a clamp) to the fuel filter on the motor. No quick release fittings at all. Tired of leaks and trying to figure it out.
Bowl on carb is full when I take the bolt out...I cannot think of anything else that might be helpful. Anyone got any ideas? Oh, Last thing, I reconnected the coils up to use the #2 coil to fire the #3 plug and vice versa - moved the wires that drive the coil. It started raining while I was doing that so I did not finish. Did get jolted about 5 times with the spark. It felt like a really good spark but you know how that is.
So. Magic time. Cheap fix is......?
