yamaha 225 ox66

[crabberoyster]

I am having trouble getting the motor started when its cold it will only fire on starting fluid then it runs fine. the colder the temperature the worse it is. the only thing I see is it seems the spark is weak don't know what would cause this. once it gets started it runs fine. and will fire right back up right away then when it sits a while and cools down same thing wont start.

[ausnoelm]

Do you think using starting fluid is somehow fixing the spark when it's cold?

[TownsendsFJR1300]

+1^^^^


Your pretty much answered your own question with what you've posted.

If it starts with starting fluid WHEN COLD, the choke system is NOT WORKING. The choke system allows for a richer mixture(or starting fluid) for cold start.

BTW, for the two stroke engine, starting fluid is not good to use. If needed, use pre-mix fuel/oil in a spray bottle.

Can you post a full model # and year?

[crabberoyster]

problem solved it was a bad wire harness from the control box seems crazy but that was the problem tried another box/harness and started right up.

[TownsendsFJR1300]

problem solved it was a bad wire harness from the control box seems crazy but that was the problem tried another box/harness and started right up.

Not crazy at all... Thanks for the update!

[crabberoyster]

now I am having a issue where when the motor warms up it loose fire on some cylinders wont rev up if I unplug the thermo sensor on the top of the block starboard side has 2 black wires with yellow stripe it will run fine except for idle to fast. any ideas on this problem?

[ausnoelm]

No idea what you are trying to say there, make sure that whatever you are trying to "fix" is not perfectly normal.....

[crabberoyster]

ok when the engine starts and is not up to operating temp it is running fine once it warms up to operating temp it is missing on several cylinders and wont take any throttle. if I unplug the thermosensor it will pick up on all the cylinders and run good except for a high idle. i have done a ohm test on the thermosensor and it checks out good so i don't know where to look next.

[rodbolt17]

as you refuse to post a model number.
all I can say is some OX66 motors are designed NOT to spark at certain RPMs, others will.
simply depends on the model.

I still need an alternator for my ford truck.

[ausnoelm]

ok when the engine starts and is not up to operating temp it is running fine once it warms up to operating temp it is missing on several cylinders and wont take any throttle. if I unplug the thermosensor it will pick up on all the cylinders and run good except for a high idle. i have done a ohm test on the thermosensor and it checks out good so i don't know where to look next.

Testing things when you don't know what the test result should be is useless, whether you are testing with meters or disconnecting things, get the model information asked for and start again.