RODBOLT-- 01 225 OX-66 O2 sensor readings?

I just got my o2 sensor diagnostic sensor harness in today. I am trying to troubleshoot a high rpm running condition. When I first run the boat away from the dock, I get about 5300 rpm. After it gets good and hot after about 20-30 minutes, I only get about 5000rpm and I can feel the engine surging a tiny bit and I can hear the engine rpms varying quickly(breaking up) Hooked up the o2 sensor harness after thoroughly cleaning the sensor and It averages about 0.6V It quickly varies from 0.54 to about 0.67V. First off the book says .3-.6 MILLI-Volts indicate a good sensor. I am reading .5-.7Volts, noy milli-volts. When I cover the #1 throttle plate hole with my finger, the reading goes from 0.65ish to about 0.74ish after about 4 seconds. with my finger still in place, it eventually drops back down to 0.67V. When I remove my finger from the hole in the throttle plate, it goes back up to 0.74ishV and then back down to 0.62ishV. It is supposed to spike high when covered and then spike low when uncovered. It never goes low. I let the engine warm up for over 10 minutes, no codes, cleaned o2 sensor, link and sync'd.
What is your interpretation of these numbers?
TOmorrow is going to be fuel rail pressure testing.
Any ideas?
Thanks!

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

Forgot the model number:
SX225TXRZ

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

Anybody?

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

Please don't yell at Rodbolt , he might get mad and stop helping all of us . Thank You

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

markernineteen said:

Please don't yell at Rodbolt , he might get mad and stop helping all of us . Thank You

Click to expand...

who is yelling?

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

Have you tried looking at your boat side fuel system yet?

http://forums.iboats.com/showthread.php?t=283269

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

Re: RODBOLT! 01 225 OX-66 O2 sensor readings?

JustJason said:

Have you tried looking at your boat side fuel system yet?

http://forums.iboats.com/showthread.php?t=283269

Click to expand...

Checked the pickup, checked the ASV, all ne lines, all new fittings, brand new 60GPH racor unit, new USCG (thick) 3/8 line from the tank to the filter under the cowl just to make sure no pinched fuel line.

Re: RODBOLT-- 01 225 OX-66 O2 sensor readings?

those numbers seem ok. do you notice any other strange things? are fuel consumption numbers of at all?
When I had O2 sensor problems, I went from cruising at 12-14gph, then after an hour of running it would spike to 22gph. I would shut off the engine and it would go back down, but then would get back up again.

have you seen this post? disregard the bench/flame test as it is useless.
www.boatsetup.com/O2sensor.pdf

also, have you tesed your spark plug caps to make sure they are in spec? they can do squirley things at high rpms under load.

Re: RODBOLT-- 01 225 OX-66 O2 sensor readings?

cousinabe said:

those numbers seem ok. do you notice any other strange things? are fuel consumption numbers of at all?
When I had O2 sensor problems, I went from cruising at 12-14gph, then after an hour of running it would spike to 22gph. I would shut off the engine and it would go back down, but then would get back up again.

have you seen this post? disregard the bench/flame test as it is useless.
www.boatsetup.com/O2sensor.pdf

also, have you tesed your spark plug caps to make sure they are in spec? they can do squirley things at high rpms under load.

Click to expand...

The only problem is breaking up at high rpm. I put a gauge on the fuel rail and it is going wacky when the condition occurs. I have a fuel problem for sure. I have some more tests to determine what the source is that I will complete tomorrow. I did check the plug caps and they are all fine. That is a nice write-up in the link that you posted. Basically the same thing as the tech bulletin, but alot more in-depth with explanation. I have not checked my fuel consumption, but I will sometime.

I am concerned with the O2 sensor output voltage. Everything says that the reading should be between .3-.6 Mine is typically just above .6 and it does not drop down to show a lean condition when I remove my finger from covering the throttle plate hole, it actually goes back up to .7ish for a few seconds and then returns to .6ish

Re: RODBOLT-- 01 225 OX-66 O2 sensor readings?

Have you actually done the fuel test with the clear line and the T-block with gauge?
If your fuel pressure is bouncing around it's only 1 of a few things.
Your getting airbound, your pump is crapping out (not likely), the fuel pressure regulator or the line that controlls it is bad.

I wouldn't worry at all about your .1 of a volt differential. Not many meters read identical on the millivolts scale anyways.

Re: RODBOLT-- 01 225 OX-66 O2 sensor readings?

have you cleaned the screen in the fuel pressure regulator?

Re: RODBOLT-- 01 225 OX-66 O2 sensor readings?

cousinabe said:

have you cleaned the screen in the fuel pressure regulator?

Click to expand...

Yep. Injector screens and pump screens are clean too. I'll find out tomorrow if the fuel problem is pre-VST or Post-VST. I shut it down at WOT when it was breaking up and squeezed the primer bulb. It only took 1.5 pumps till hard which indicates a full VST, but tomorrow I will actually measure the amount of fuel when the VST is normally full vs. when the engine starts breaking up. That should point me in the right direction. I will also monitor pump voltage at the same time to rule out any elec. problems. Fun stuff

Re: RODBOLT-- 01 225 OX-66 O2 sensor readings?

just so we're clear, part #13.
http://www.boats.net/parts/search/Yamaha/Outboard/2001/SX225TURZ/FUEL INJECTION PUMP/parts.html

Re: RODBOLT-- 01 225 OX-66 O2 sensor readings?

I can't see the picture only iPhone, but I assume that you are calling outthe small wire mesh screen behind the fpr. I removed the fpr and cleaned out the screen behind it. It had a couple of small specks in it, but nothing that would block it or restrict it. Looking at the design and location of the fpr and the screen, the screen is before the fpr so if the screen were clogged, it would actually cause the rail pressure to be too high. Just an observation.

So my boss called me at 8pm last night and said that I am flying out to Atlanta at 6am this morning so no playing with the boat today of tomorrow......

Re: RODBOLT-- 01 225 OX-66 O2 sensor readings?

your numbers are a bit on the high side indicating a rich fuel condition and the ECU will try to lean out all 6 injectors.
.5V is 5 mV.
sorry about the delay in replying but the past few days I could not get into iboats for some reason. was so slow the machine would time out.
check your lift pumps, if one leaks fuel goes rich and the O2 sensor picks it up .
.3V is engine lean. .9V engine is pig rich.
and the ecu constantly corrects which is why the voltage should rapidly scale up and down between about.3 and .6v
bad plug cap, high or low fuel pressure,low voltage to the ECU, can lead to rich running as can a leaking injector.
if the ECU detects low battery voltage it assumes its input is correct and widens the injector on time pulse width.
below about 1800 RPM you should see about 9V at the pump, above that the full 12V.