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2000 J70plssd #3 cylinder dead has spark and excessive fuel

S

scottro

New member
I have been battling with this motor for a while. It started with a bad timing base and I replaced it. I had no/intermittant spark on #3. I have solved that problem and reset the timing and thought I was good to go it seemed to idle well. I took it out on the water and no power. Started pulling plugs under load and the #3 cylinder still wont fire. So I drove home and switched the #1 and #3 carbs and the problem did not migrate.

I also switched the #1 and #3 coil. I measured the power pack output with a DVA and everything was in spec. I checked the timing on all three cylinders by trisecting the flywheel and they were all in time.

I removed the #3 carb to check the reed valves and they looked fine. I cranked the engine to see them function and found fuel pushing up from the bottom of the crankcase thru a small notch in front and below the reed valves. I think the crankcase was full of fuel and this was most likely from crankcase pressure.

I removed the recently rebuilt VRO and verified the VRO seals were not damaged or leaking. The crankcase pump section of the VRO was dry and no signs of fuel. I applied 5 psi to the crankcase pump section of the VRO and I could not find any air leaking from the VRO and could hear the spring and diaphragm moving.

Does anyone have any thoughts on additional items to check or recheck.
 
Check position of #3 cylinder sleeve.----Elaborate on this excess fuel in the bottom cylinder.----You are aware that there is an internal passage way that is designed to recirculate oil / fuel from #3 to #1 cylinder
 
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racerone said:
Check position of cylinder sleeve.
Click to expand...
Would I be able do that with a scope thru the spark plug hole. I was going to get my scope and verify the ports are in the same location on #3 vs #1 and #2.

also forgot to mention 135 psi on all cylinders
 
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Correct use a scope.-----I have a 3 cylinder block like that on hand with the sleeve rotated out of position.----Simple to check this.
 
racerone said:
Correct use a scope.-----I have a 3 cylinder block like that on hand with the sleeve rotated out of position.----Simple to check this.
Click to expand...
Just checked them for port position and made sure to keep the camera in the same orientation for each cylinder. Checked 3 first and rotated engine to put 1 at the bottom of the stroke and then 2 to the bottom of the stroke. They are very close if not identical. All cylinders looked in fine condition.
 
Now you know for sure they are OK.----Something you did not know before the inspection.----Carry on with further trouble shooting till you find the issue with the motor.
 
racerone said:
Now you know for sure they are OK.----Something you did not know before the inspection.----Carry on with further trouble shooting till you find the issue with the motor.
Click to expand...

Went back to troubleshooting starting point. Again verified spark and then kept leaning out #3 carb in 1/4 turns and waiting 30 seconds to see if there was a response after approx. 1 1/2 turns the carb seemed to start working. I was flooding this thing the whole time.:mad: I tuned it and the operated the throttle and the engine was very responsive compared to before.

I forgot I was adjusting that carb when I had intermittent spark and must have run it way out. forest thru the trees!

Still have to get it on the water so I still have my fingers crossed.
 
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