72 650 3 cyl no fuel top cyl

[walter w]

History, On this 650 i have replaced both floats, needles and seats, cleaned carbs and replaced fuel diaphram. Ran it last weekend for a few hours and it ran great no issues at idle or full. Changed the tank of gas and after 2 minutes fun was over. Lost power, as I was a mile or so from the dock I ran it back under full power under 2 cylinders and every once and awhile the other cylinder would kick back in then out.
if I let it sit for a few minutes and start it all 3 cylinders run but the top drops out very quickly and i am stuck with 2 again. Pulled the plug out of the top and it is sooty but dry. replaced fuel line and bulb no change. seems to get no fuel to the top cylinder most of the time except if run full throtle it kick in and out. Any ideas or do i rip the carbs apart again and check for infatration of juck?
any ideas would be appreaciated

Walt

 

[WillyBWright]

Re: 72 650 3 cyl no fuel top cyl

Since it happened after connecting another tank, I'd check that tank for water.

 

[jebeebe]

Re: 72 650 3 cyl no fuel top cyl

History, On this 650 i have replaced both floats, needles and seats, cleaned carbs and replaced fuel diaphram. Ran it last weekend for a few hours and it ran great no issues at idle or full. Changed the tank of gas and after 2 minutes fun was over. Lost power, as I was a mile or so from the dock I ran it back under full power under 2 cylinders and every once and awhile the other cylinder would kick back in then out.
if I let it sit for a few minutes and start it all 3 cylinders run but the top drops out very quickly and i am stuck with 2 again. Pulled the plug out of the top and it is sooty but dry. replaced fuel line and bulb no change. seems to get no fuel to the top cylinder most of the time except if run full throtle it kick in and out. Any ideas or do i rip the carbs apart again and check for infatration of juck?
any ideas would be appreaciated

Walt

Wouldn't run it too long on 2 cyl as "no fuel-no lube"

 

[walter w]

Re: 72 650 3 cyl no fuel top cyl

thought about the water in the fuel but have drained floats and bowls and hooked back another tank with fresh fuel (old one from before) but that does not explain the fuel getting to and then stopping (intermitant) to the top cylinder. and as for the no fuel no lube, yes i agree but if it gets fuel now and then the lube might have been enough to get me back to shore without melting the piston. I realize that I cannot run it on the 2 cylinders only thats why I am checking here to see if anyone has any other ideas to the cause before I redo the carbs and fuel diaphram.