Im running a 2000 yamaha 150 0X66 SWS II, SX150TXRY. From time to time idling it will get a sneeze and stall. Start right back up. I bought the shop manual and tested spark plug caps- found 2 out of spec, replaced em. Compression is 115-120 across the board. Tested low pressure pumps, 1 would not hold pressure/vacuum. Replaced both of em. Checked VST and regulator screens- o.k. Engine mounted fuel filter and water seperator are new. New spark plugs too. Even ran engine with clear hose to check air leaks- o.k.. Ran auxillary fuel tank hooked to engine fuel filter, still will sneeze at idle & stall sometimes. Pulled O2 sensor, badly carboned up with chunks of carbon, looked like coal. cleaned O2 as per yamaha bulletin found on here. Checked and cleand transfer tube and O2 block. Re-assembled and ran up to operating temp. Checked voltage at O2 plug engine harness side. At idle I was getting .010-.012 volts. Tried to force rich by covering hole in number 1 throttle plate, no change. Tried bringing idle up to 1500 and recheck got same readings. The boat is not currently in the water and all checks were done with engine running in a water tank.
Question: I've read the propane torch test the manual outlines is useless. I've also read you want the engine temp over 120 with a range of .3-.6 volts and it to toggle but cant find under what conditions to test the O2. Does the engine have to be run under load to be tested? Does it have to be above a certain RPM? Any info would be much appreciated.
Thanks Mike
Question: I've read the propane torch test the manual outlines is useless. I've also read you want the engine temp over 120 with a range of .3-.6 volts and it to toggle but cant find under what conditions to test the O2. Does the engine have to be run under load to be tested? Does it have to be above a certain RPM? Any info would be much appreciated.
Thanks Mike
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