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Hi, In December last year my 2004 90HP Yamaha's starter packed up. After it was fixed and re-assembled all my engine trouble starter. Poor idling and in gear, the enginge dies. CDI problem was diagnosed, but after putting in new one, problem still persists. Carbs was ultrasonically cleaned 3 times, new fuel line was done. Engine was tuned by 'experts'. Idling still bit poor, but if I open throttle from idling the engine is holding back, lack of power as if running on only 2 cylinders and then it suddenly goes with speed of light and no problems at high speeds. I've spend lots of money up to date to diagnose the cause and can't spend much more. I personally think that the problem lies in the pulser pickup, coil pack or high and low speed coils underneath the flywheel. Not a fuel problem. What is your opinion? Waiting for your reply, thank you. Christo
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my opinion?
find some real technicians with actual test equipment and training.
that ign system uses a single fixed pulser coil to spark cyl 1&3.
spark on #2 is made by the crank position sensor.
loose a pulser and you lose 1 or 2 cyl spark, depending on the coil failure.
loose a CPS and you lose spark on #2 cyl.
it is a simple matter of testing inputs to the CDI and outputs from the CDI at the failure RPM and load.
don't forget that fuel pumps can fail.
head gaskets can fail.
ex divider plates can fail.
all can be observed by careful inspection of the spark plugs with a trained/experienced eyeball. -
leaking fuel pump can and will dump too much fuel into the crankcase on #3 causing it to not light off properly even if it is getting good spark. Lower RPMs could be affected more that high speed
something to look forComment
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