2001 SX225 OX66 running rich

[Inpursuit]

Hi new member here.
I have a fairly low hour SX225 nthat is running very rich and fouling plugs, I can change the plugs and after a short while it will start smelling very rich while on plane and misses badly at idle.
Any ideas where to start?
Thanks in advance, Frank

[jb123]

low pressure pumps, sticking needle seat in VST, bad plugs... what service HAVE you done ?

[Inpursuit]

I rebuilt the low pressure fuel pumps and water pump, replaced the fuel filters and as general maintenance items.
In the year that I have owned it I am on my third set of plugs and it's needing another set now.
I know the EGR needs regular maintenance, and the thermostats should probably be changed, injector screens should probably be checked, TPS should be checked and i'm sure I missed something.
While looking at the Yamaha repair manual I didn't notice a float level setting for the VST?, is there one and where is it measured from?
Money and time is kinda tight at the moment so I have been doing a little at a time but would like to know what would be the next most important thing to do.
Also would a dirty EGR cause it to run rich?
Thanks

[rodbolt17]

could be cause there is no EGR on an ox66.

[Inpursuit]

Ok I meant to say 02 sensor, any thoughts where to start?

[Tucker]

Is your oil pump linkage adjusted correctly? Have you confirmed oil ration by amount of fuel and oil burned? There's a good thread on here about that along with pics.
I believe I read here that if the 02 sensor is bad it will send a default signal to the ECU to run rich. Need regular maintenance on the 02 sniffer port, could be carboned up.

[jb123]

most common is lp pumps, i would recheck,unbolt,pump ball, if ANY leakage, replace the WHOLE unit

[Inpursuit]

Oil pump linkage has been adjusted, low pressure pumps have been rebuilt and hold pressure as long as I can stand there holding pressure on the primer bulb.
Removed the 02 sensor, mounting block and tube and the whole thing was plugged up. Cleaned all the parts and checked the sensor and it shows it's good.
I am going to check the VST and TPS, install new T'stat's, check injector screens just so I know everything is good to go.

[rodbolt17]

O2 sensor output voltage MUST be tested after cleaning.
the flame test is worthless.
fuel rail pressure MUST be tested over pressure will cause a rich condition.
CDI output voltage must be tested,low voltage will cause plug fouling.

[Inpursuit]

So the 02 sensor should be tested on the motor with it running?, please explain why the flame test can't be used?

[Tucker]

Yea, I've seen that flame test on an O2 sensor service procedure all over the net. If the RB says it's doesn't work, there's a good reason why it doesn't. Is the test procedure listed in the shop manual?? If not please explain how to do it.

[Inpursuit]

The manual shows the flame test

[Tucker]

I'd still follow rodbolt's lead and forget the flame test. Let's see if he comes back with procedure on how to check the output voltage. Not sure what happens when the sniffing port is blocked.

[Inpursuit]

I agree as to knowing why

[rodbolt17]

I cant tell you why the flame test is worthless.
I CAN tell you I have done the flame test seen it pass the flame test and FAIL to work on the engine.
I have also seen them fail the flame test and work perfectly on the engine.
its also why there are 3 other tech bullitens on how to properly test O2 sensor output on the engine.
I really really dont care if it works on the bench, I really really care that it works on the engine.