Super Dave
Cadet
- Joined
- Sep 1, 2008
- Messages
- 6
Hello - new here (again) 150TXRZ on Century 1900: Last 1 1/2 yrs or so having intermittent idle issues, pop/sneeze after idle slowly crawls down to 300 rpm from 600-700 rpm in or out of gear - only after driven a while & stopped (hot soak) or of course trying to drive-on trailer or dock -- runs fantastic at high (3000+ rpm) speed - however I hear what sounds like misfire at 1/4-1/3 throttle if held there while climbing up but not quite on plane(heavy load). I'm a Toyota guy 20+ yrs but still remember carbs well and have all the tools so I r/r & overhauled all 3 w/genuine Yamaha kits. Also replaced 10 micron, plugs, t-stats, and checked pumps (about 1 year old). Carbs were cleaned THOROUGHLY, soaked, sprayed and blown w/compressed air. I'm reluctant to run wire through orifices, especially the pilot circuit air holes. All jets looked bright gold and clear once viewed through a 30x magnifier. Once all completed I was excited that it was (probably) cured, when running on the hose at idle 800-900 out of the water, I get a 'ppmmmmm-pmmmm sound on occasion and a puff of blue smoke from hub immediately when the sound occurs. Generally would idle all day on the hose, but add back pressure of the water and the 'pmmmm' sound sounds more like a muffled pop/backfire (even though there is NOT a back fire - just sounds like a muffled one), some smoke comes out of the water then undoubtedly it will start to idle down and finally sneeze upon stalling. Sounds/feels like a missfire especially when running under 1/2 throttle under load, but all signs point to lean. (if it were a car the opposite would be my diagnosis, loading up & flooding - this is not the case here. Choke feathering when idle starts to drop will save it if caught in time. Questions: Did I miss something? What is the correct turns out for the pilot screws? (in case I forgot to count upon disassembly) Could a coil pack or two be fooling me - and be so intermittent?
Note: Fuel system clean, new lines last year, new 10 micron every year, was running e10 but not anymore, add ring free every other tank, compresion 108-114 all 6, reeds all look great and all 36 are closed, carbs were synched properly, timing was checked 5deg ATDC idle,
Note: Fuel system clean, new lines last year, new 10 micron every year, was running e10 but not anymore, add ring free every other tank, compresion 108-114 all 6, reeds all look great and all 36 are closed, carbs were synched properly, timing was checked 5deg ATDC idle,