Yamaha 200 OX66

[eljefe]

We have two OX66 motors on the boat. One will not start without using starter fluid. Once it's started it runs fine and will start again shortly after you run it. But if it sits overnight it will not start again without help. The hp fuel pump was recently replaced because of typical problems from that.

Advice?

[21XDC]

Are you priming the bulb/s? Need new bulbs?

[JUST-IN-TIME]

check compression
check spark

you need to look at plugs

could be from
fuel pumps
o2 sensor
spark plugs
sensors

get a manual also

[toledo freak]

sounds like possibly a temp sensor problem failing to tell the ecu your motor is cold thus not allowing cold start features

[ghind]

Don't use starting fluid, you will scuff your cylinder walls doing that. It is a 2 stroke and needs fuel AND oil.

Find another way to diagnose the engine.

Have you plugged in the diagnostic indicator?
Have you followed the sticky for low pressure fuel pump testing?
What fuel pressure are you measuring at the schrader valve?

When it did start using the fluid how did it run?

Greg