Re: yamaha saltwater series II 250HP MOTOR info
the above LIT # is the yamaha service manual but as we still dont have a model number there is no way to verify what you have.
if they are 97's and not 98's and you use the wrong information then at a minimum your gonna beat youre head on a wall and the maximum is to pop a powerhead due to incorrect tune-up specs.
thats why the model number is so important when actually working on a motor.
the low pressure fuel pump diaphrams tend to last less than 3 years and I reccomend periodic replacement as maint.
yes a ruptured fuel pump diaphram can and will pop a piston or a rod bearing.
the oiling system is very reliable,if correctly maintained.
that also means periodic testing of the alarm system and NEVER remove the engine oil tank strainer without first completly draing the engine oil tank.
the early 3.1L EFI motors had an issue with the stabilizing foot at the bottom of the oil level alarm switch that if transfer becomes inhibited the alarm wont work and the operators first clue may be the rod hanging outside the block.
if the strainer is removed from the engine oil tank the seal on the end of the strainer MUST be retrieved and discarded.
replace with a new seal.
the O2 sensor MUST be periodically cleaned and tested as per the tech bulliten, pay no attention to the flame test in the manual or the tech guide. use the other three tech bullitens with a multimeter and a test harness to properly check O2 sensor output.
yes a faulty output can pop a piston above 4000 RPM.
somewher there is a tech bulliten on the T-stat covers, you need to check for it.
there is also a tech bulliten on both the O2 sensor draw tube and the mid year change in 03 on the mounting gaskets for the O2 sensor(applicble if the powerhead was replaced since mid 03).
maint up to date on an OX66 motor?
I have never witnessed it unless its a motor I sold and have maintained.
a simple quick test of the oil alarm and transfer rate can be done.
insure the remote tank is at least 1/2 full, turn the key on engine off, remove the engine oil tank water trap and allow the tank to drain into a suitable container. about 1" below the low mark the alarm should sound,3 bars flash on the tach and the transfer pump kicks on. with the key still on reinstall the water trap and time how long it takes to almost refill the tank.
transfer pump will run for 180 seconds and should have the engine tank about 2/3rds full at a minimum.
if the alarm wont sound turn the key off and finnish draining the engine tank and pull the engine tank oil switch assy and test as per service manual and the 3.1L oil tank tech bulliten.
remember all the 3 position switch on the engine tank does is command pump ON, pump OFF and if the level drops to far the bottom switch(SW3) simply commands the alarm ON and RPM reduction.
the normally closed switch in the remote tank simply alerts the operator that there is enough oil for automatic transfer. if the switch opens or a wire breaks then the yellow lamp or center bar is lit and automatic oil transfer is inhibited.
for all normal oil transfer functions, other than the above alarm test, the engine must be running for automatic transfer.
thats why we always beat up on the model numbers and since 06 the model AND the seriel numbers, without it we cannot properly ID the motor or its ign/fuel system.
when running and propped correctly that motor should turn 5300-5500 RPM.
