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Old 08-17-2011, 08:05 PM
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Default Yamaha 150txr carb MYSTERY issues

New here (love this place) - I have a Yamaha 150TXRZ on my Century 1900, past year or so having issues with idle driveability. Before last trip...new 10 micron, 3 Yamaha carb kits & THOROUGHLY cleaned/checked synch'd/linked, timing reset, idle speed reset (700 in water/neutral), plugs, t-stats, nut/bolt check/lube. FIlled with non-E and ring free NOW for my mystery. Runs perfect but seems rough at idle. Once run up, stopped (hot soak), then restarted, often will idle for a few minutes then drop 6,5,4,3,jolt/stall. The jolt could best be animated as 'idle-idle-pmmmm-pmmmm-stall' sometimes a sneeze but often get the 'pmmmm' type noise. When it does this idling on hose out of the water, the 'pmmm' is immediately followed by a puff of blue/gray smoke from the hub. Only other symptom is when dragging out the almost-plane-speed under heavy load/large wake - it makes the same pmmmm sound which sounds like a misfire, but doesnt interrupt power. My biggest peeve is that my Dad (not as mechanically inclined) has ZERO problems with his 1996 model 150TXR, and never has to do much to it, and it sits a lot more than mine. Any help/tips?? Thanks in advance.
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Old 08-17-2011, 08:09 PM
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My title sounds like "carb mystery", I honestly think my carbs are pristine now and not the issue, plus the issue is intermittent. Seems better after the big tune up, but still exists.
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Old 08-18-2011, 03:42 AM
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isolate issue by using an aux tank, hose and ball hooked to motor filter
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Old 08-18-2011, 04:55 AM
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I have a 2004 F60 with the same problem. While cold it is fine. The problem seems to occur after the engine warms up. It has been at the shop for 2 months and they cannot find the issue. Will post if the problem is found.
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Old 08-18-2011, 07:23 AM
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If the aux tank doesn't help,check the fuel pumps for a pin hole in the diaphram.This allows fuel directly into the crankcase and especially causes problems after the engine warms up.The hole may be hard to see.I rebuilt the pumps on my 150TLRD and the problem went away.Just something to consider.
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Old 08-18-2011, 02:40 PM
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How long have the fuel pumps been on? Should be changed about every 3-4 years. Easy way to check is to unbolt the pumps and pump the primer bulb until real hare. Then check the back of the fuel pumps for gas dripping out. When you rebuild the carbs did you clean the pilot circuit good? Did you set the pilot screws correctly? There are 2-screws for each carb and the settings are very different. One is 3/4 turn and the other is 1-1/2 turns.
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Old 08-18-2011, 04:10 PM
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Pumps are about 2 years old, maybe only 100hrs or less since replaced, cannot get any fuel from the crankcase hole when primed, but doesn't mean one of the paddles isn't sticking inside. I have 2 new ones saved inside for next replacement, I may bolt them on anyway (they're cheap enough). The pilot circuit is crystal clean upon overhaul (I didn't stick wires into the orifices, nor will I, but blew them all clear and re-inspected with a good magnifying glass) the aluminum pilot holes under the brass plug are clean-shiny aluminum and clear, the pilot air jets are the same (but bright gold brass). My manual states for this year to set all pilot screws 1-turn out. I've read something like port=5/8 and starboard=1 1/8 or vice-versa?, but nothing definite (any clarification?). I did the old vacuum hose in the ear through each of the 6 barrells and all sound about the same to me. I also was told continue to turn out the pilot jets 1/8 turn at a time til it runs ok, but thats nearly impossible since there's 6 and minor adjustments don't make significant changes -- may be my problem (the screws) since 2 years ago when I o/hauled the carbs I don't remember the setting before removal -- at that time I had water inside but tank is all clear and water is no longer an issue. It caused main jet plugging at 3/4-w/o throttle, definitely runs great at those speeds, all issues are 1/4 to idle.
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Old 08-18-2011, 04:18 PM
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hey Shott, is the F60 a carbed 4stroke 2cyl? Mines the "old faithful" 2-stroke - What are you guys thoughts on ignition coil packs causing these issues since its almost always after hot-soak or in direct sunlight with quite warm cowling temps (i'm in the sunshine state where the sun seems to lie about 200' overhead). I can't wait to try my new fuel pumps - even though I never seem to have a starvation at speed, but doesn't the motor rely on these pumps more at idle since there's no real air flow to 'pull' the fuel out of the carb.
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Old 08-18-2011, 06:29 PM
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Had same issue with a pair of 200hp carbed Yamahas. Idle jets should be removed and soaked in OMC Power Tune foaming type cleaner in a glass jar overnite. Fuel deposits reduce the jet size an give a lean mixture at idle. Results in rough idle and sneezing.
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Old 08-19-2011, 06:46 AM
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Cuda I have the official Yam shop manual for my 1998 S200TXRW motors that I no longer have. There's testing procedures for the coil packs and ign stator along with everything else. I sell it to you for say... $35 plus shipping. I'm agreeing with BCH and think it's in the idle circuit. I'll check the turns out when I get home and get the manual number. Have you pulled the screws all the way out and checked the tips for bending, deforming etc. Sounds like you got the carbs squeeky clean.
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Old 08-22-2011, 07:43 AM
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Quote:
Originally Posted by tucker99 View Post
Cuda I have the official Yam shop manual for my 1998 S200TXRW motors that I no longer have. There's testing procedures for the coil packs and ign stator along with everything else. I sell it to you for say... $35 plus shipping. I'm agreeing with BCH and think it's in the idle circuit. I'll check the turns out when I get home and get the manual number. Have you pulled the screws all the way out and checked the tips for bending, deforming etc. Sounds like you got the carbs squeeky clean.
I have the clymer and a few photocopies of a few pages of original from a friend who has since moved so no more access to the OEM manual. I think more will be different from the 200's but I don't have the turns-out adjustment from Yamaha, the clymer states 1-turn out, I think every couple years is a little different. As far as checking the screws, yes - clean and straight, they were also out when I soaked'em. Should I expect to find more trash in the air (pilot screw) side under the brass plug -or- in the fuel jet? I don't think the low-speed jet is removable but I soaked the whole carb once ALL removable was removed and the low speed jets looked all clean plus blew compressed air through all with more spray cleaner.
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