I really need OX66 HELP! Rodbolt? Anyone?

[cedlin1234]

Alright, guys. I am having a rough time with my 1999 V200TLRX OX66 Outboard. Here is how things went down. I bought this boat from MN in April. I live in Colorado and brought it up to 5280 feet. The motor needed some maintenance so these are all the things I did.

-3 new LP fuel pumps
-Most filters, VST, On-board fuel filter, Water separator on the boat, (not oil filter)
-New lines from Water separator to engine
-New primer bulb
-New plugs, and Plug boots, (Tested resistance)
-O2 sensor looked terrible so I cleaned it up
-Cleaned out the High-pressure regulator screen

The last 2 weeks I have had this motor running like a top. Hitting high RPM's ~5300 with my 21 pitch prop. Yesterday, I took the boat up to an even higher altitude (7200'), changed the prop to a 19 pitch, and had a bear of a time with her running right. Felt like she was fouling plugs, missing, not gaining full RPM's etc. She took a while to get on plane and when she did, still didn't run quite right. The biggest problems were a surging and loss of WOT RPMs(significant loss! not just altitude loss).

Now I am starting to put 2 and 2 together. When I took the boat from MN to CO, it had similar issues, missing, fouling plugs, etc. After all the work listed above, I thought I had fixed the problem. Take it up 2000 more feet and the problems are occurring again. I have not retested it at my normal altitude of 5280 since yesterday but I plan to. The only other problem I have been having at either altitude is this. I can't get "warm-up RPMs" on the motor. It goes to 700 right on startup. No matter what the conditions or however cold it is. Then when I put the motor into gear (forward or reverse) it ends up stalling. about 400-500 rpms and then dies out. Starts right back up, no problem, but dies during slow speeds for whatever reason. (Think slow *****ing a spot to look for fish on the graph).

So to recap my issues:
1) The motor doesn't seem to go to the Std. 1200 RPM warm up, just straight to 700 RPMs. Once it goes into gear, RPMs drop to 400 or 500 and typically stalls out. Motor starts back up fine and can be saved from a stall by pushing up on the throttle.
2)After taking my motor up another 2000' feet in altitude from running great at 5280', the motor was missing from the beginning. Ran rough, loss or WOT RPM's, and surging.

Here is where my thought process is at now based on everything I have already done on this motor:
1) Thermostats need to be replaced. It could be 17 years with the Original equipment (the LP fuel pumps were). Could that be causing my warm startup RPMS or idling issues?
2) I need to verify the TPS is working and in the proper voltage range.
3) Check the plugs for fouling (Would the extra HAltitude cause the plugs to foul? I thought EFI motors could adjust Fuel to air ratio on its own?)

Can the motors run Rich by default? Is there a way to sync the motor to work better in High altitude environments?

THANK YOU FOR THE ADVICE! I NEED IT BADLY!

[cedlin1234]

Also, my update for tonight is this. I checked my TPS using Rodbolts old post with instructions. I was at .58 volts idle (orange and pink wire) and then I took the orange lead and connected it to the red wire and the full throttle reading was 4.98(testing pink-red). That last reading was taken after I adjusted the TPS back to the recommended .62 volts. Just for fun, I then took the lead out of the pink and connected it to orange (testing orange-red), repeated the full throttle test and I had a reading of 4.38 before and when opening it to WOT it went down to .75? Is that normal? Did I do something wrong?

So regardless, I think my TPS is fine unless that last reading is suspect. I also read some things about bad Thermostats causing fouled plugs. Well wouldn't you know, I removed both and they are both stuck wide open. I am going to my local yam dealer tomorrow to get the replacement Tstats. I see how that could cause a rough idle condition and fouled plugs since the motor wouldn't be allowed to warm-up properly.

But I am still wondering why my motor won't go to "warm-up RPMs". I guess I will change the Tstats and see what happens when I hit the lake but I would think the motor would know to go up to warm-up idles until the temp is reached and then the RPMS would go back down to the recommended 730-750 out of gear, 650 in gear.

Any input on that? I think the tstats will be a HUGE step in the right direction. I'm just not sold that solves everything. Could it be thermosensors? I thought if those were bad I would have high RPM's that wouldn't drop. Thoughts? Thanks for the help everyone!

Pic of Tstats

[rodbolt17]

check the MAP sensor.
check ign timing.
should be 7*BTDC at cold start and then move to 7*atdc.
check the injector filters.

[cedlin1234]

Rodbolt, Thanks for the reply. I will replace the injector filters. Is it okay to use a small knife/box cutter to get the old ones out? Or should I buy the tool?

I looked online to buy new injector filters but didn't see any for the motor. Clean and reinstall, or buy new? Where can I get new ones? Do another motor's injector filters match an OX66?

As far as the MAP Sensor, I know where it's located, under the black plastic cover with all the other fuses and wiring. My question is how to test it? I don't own a Service manual but I assume a DVA should be enough to test it? Would a Winky Blinky throw a code for a bad MAP sensor?

I have never adjusted the timing on an Outboard. I know some are fairly easy and can be done with the motor off and just by moving the throttle and adjusting the stopper. Others not so easy. Any advice on this job? Is it fairly straightforward or should I take it to someone?

Thank you for all the suggestions and help.

[cedlin1234]

Okay, I did a little research. Connect a volt meter by back probing to the signal wire and the ground wire. Disconnect throttle cable, Start the outboard, at idle voltage should read around 1?, then gradual open throttle plates and DVA should rise. If no rise, lean condition, if stuck in higher voltage range, a rich condition that could lead to fouling plugs? What voltage on the MAP sensor would indicate a rough idle? I tend to think if my map sensor was bad, it would have a High Voltage since every time I go up in altitude the engine runs rough. Thoughts?

[rodbolt17]

first buy the correct SM.
the SM has all the voltage specs for testing each and every sensor.
the O2 sensor is for fuel trim.
the map sensor gives information on oxygen density.
the TPS gives information on throttle angle.
the coolant temp sensor gives info on block temp.
the crank position sensor tells the ECU where it is at.
the intake air sensor also gives oxygen density info.
every one of thses sensor,excluding the O2, is monitored for inrange operation. each one,excepting the O2 and CPS, has a 5v ref.
lose the correct 5V reference and the output is now garbage and can be an in range failure.
the ECU wont know the 5V is bad it is looking at the sensor output and may react,
google closed loop speed density EFI.
you can read how it works.

[99yam40]

Rodbolt, Thanks for the reply. I will replace the injector filters. Is it okay to use a small knife/box cutter to get the old ones out? Or should I buy the tool?

I looked online to buy new injector filters but didn't see any for the motor. Clean and reinstall, or buy new? Where can I get new ones? Do another motor's injector filters match an OX66?

As far as the MAP Sensor, I know where it's located, under the black plastic cover with all the other fuses and wiring. My question is how to test it? I don't own a Service manual but I assume a DVA should be enough to test it? Would a Winky Blinky throw a code for a bad MAP sensor?

I have never adjusted the timing on an Outboard. I know some are fairly easy and can be done with the motor off and just by moving the throttle and adjusting the stopper. Others not so easy. Any advice on this job? Is it fairly straightforward or should I take it to someone?

Thank you for all the suggestions and help.

I hate to say it, but sounds like you need to find a good Yamaha shop.
Rod said to check timing to see what it is doing, said nothing about adjusting.
Do you know what a DVA is and what it is used for?
sending injectors off to be serviced would be the best thing for you to do with yours.
they will do a flow test ,clean, and retest sending you a report.

[cedlin1234]

Awesome Rodbolt. I have obtained an SM for my motor and have been diving into some reading the past couple days. I have found the correct testing procedures for the MAP and Thermo switch assemblies on each side of the block. I am also looking for the testing procedure for the Thermosensor assembly. I can't seem to find it in the Yamaha SM. Maybe it's labeled differently but I just can't seem to find it.

Any idea how to test?

I also need to pull the injector filters still. Any idea where I can get replacements since Yamaha doesn't sell them separately?

The TPS was set to .62 but the manual I have says. .50 at Throttle closed. Is that right for the 200hp? I thought .50v was for the 250hp's.


99Yam, I confused DVA with DVM. I have been using a digital volt meter to test all my connections, not a DVA. I guess I am curious about how to check the timing. I have heard of using a timing light but still have some pages of this book I haven't scoured yet. However, I haven't found any literature on timing (except for the specifications list showing 7*BTDC and ATDC). I am fairly confident I can work out the problem, just think I need some support along the way. I feel like on a 17 y/o motor, it's time to send the injectors off. I will do that. There is a local shop offering $20 an injector. I will call them tonight.

Thanks for the help. I'll be looking forward to your replies.

Is the Thermosensor also known as "Engine Cooling Water Temperature Sensor"

See this link for a picture from the manual.

https://drive.google.com/file/d/0B7_...ew?usp=sharing

[rodbolt17]

don't sweat the jinglish.
remember that manual was printed in Japanese then translated,sometimes poorly.

that motor has two thermoswitchs and one thermosensor.
the procedure for testing any sensor is in the SM.
when you set the TPS, throttles closed DOES NOT mean throttles at idle.
means throttles fully closed and the throttle shutter adjusting screw not contacting the stop.

[99yam40]

yes that is the thermosensor.
yes on the idle stop not touching
timing light is used just like on automobiles hook to #1 plug wire fire up and see what the timing is showing at the flywheel marks

[cedlin1234]

Yeah, I'm slowly noticing the Jinglish... I got back to the motor today and here is where we are at.

Thermoswitches = In-spec. There was no continuity until they reached about 200degrees, then as both fell down to 160 degrees the continuity cut out again as per the manual.

Thermosensor = Maybe a problem here... The Thermosensor was put in cold water and specs out in range. Then at 67 degree water and still specs out. Once I put it in boiling water and left it for a minute or so the Ohm's never got into range. It stayed at 3.94kohms. Spec should be 3.02-3.48kohms. I now have this part on order.

TPS = I set it to .50v at Throttle closed. When reconnected and the screw was contacting the stop. .61~.62v. I believe this is accurate now

Oil Link Rod = I am certain I was pumping in too much oil. I had to trim the rod down a bit to get the oil lever to contact the stop at Throttle closed (yes, I disconnected the linkage to right cylinder, 4 I believe?). Should be all good here now.

MAP sensor = In spec but... I checked it out and the output voltage with back probing was 3.24v. Spec is 3.2-4.6v. My question would be. Even though it's "In-spec", is the low voltage a cause for concern or a "beginning to fail" MAP sensor?

Air Intake Sensor = Out of spec. Another sensor I checked with a failing voltage. It spec'd out at 2.27v and it needs to be at 3.4-5.3v. I took a picture from the manual of this sensor. You can view it here ->https://drive.google.com/open?id=0B7...i03Z010X2c5a3M

I also have this part on order.

Injector filters = Now Clean. They seemed a bit dirty, nothing extremly concerning but I have attached a picture of the crud I cleaned out of them. Is this fairly normal for a filter or is this considered a "bad blockage". Pic of Filtershttps://drive.google.com/open?id=0B7...GhSdDctLUxjbU0

LP fuel pumps= I replaced them recently but double checked them and they are all good, no leaks

O2 Sensor = Checked the sensor for oil and it was bone dry. Much better than before.

Intake at Throttle plates = Holding some excess oil every time I take it off, any idea why? Link to Picture here -> https://drive.google.com/open?id=0B7...kUyb0V3S19lWlU

New Thermostats went in before my last test of the boat but there was no change. So I assume that these sensors and the filters getting a good cleaning will help. Hopefully, I am on the right track.

I will tackle the timing next. Likely I will need some time for that. What do you guys think? Is that Air Temp sensor going to be the ticket to a better running motor? I am guessing the Thermosensor will help! Anything else I should check while I'm under the hood??

[rodbolt17]

chasing ghosties and hunting wabbits never helps.

did you actually google speed density closed loop EFI?

first thing you must understand is why the sensor is there and what does it do.

you can look at clean and fart around with an O2 sensor all day long,,, did you actually check the output voltage in accordance with the SM and the 3 tech bullitens???????

this stuff aint hard or I would not be able to do it.

the flame test for the O2 sensor is a teat on a boar hog.

[cedlin1234]

Yeah, I took the time to read a bit about it. It certainly makes sense, every sensor is doing it's own job to help the EFI run best.

I also did test the O2 sensor and it is within Ohm range and voltage.

The IAT that didn't spec out was described as this, "The intake air temperature (IAT) sensor, otherwise known as the air charge temperature sensor, is used by the powertrain control module (PCM) to determine the temperature (and therefore the density) of air entering the engine." So, therefore, since it tested bad I would determine that the computer isn't receiving the signal to the ECU that determines air density/temperature. The IAT must regulate injector control among other things so this may be my issue.

Per google, "A bad IAT sensor can cause all kinds of driveability problems including a rough idle, surging, stalling, and poor fuel economy." I think I am on the right track with that sensor.

I also read, in order for the ECU to calculate air density it needs MAP and IAT sensor data. So if the IAT is the issue, that's why it won't adjust for altitude.

I will try both sensors that I ordered to replace the bad testing ones. Hopefully, we are working towards the right direction. I will test the other sensors soon as well. Ran out of time last time I was out.

How do those injector filters in the picture look? Do you think my MAP sensor is okay with a low but in-spec voltage?

[cedlin1234]

Interesting update. Ran the motor without the new parts and the idle was still low and it did not go into a Warmup Idle. I took the cover off and felt the heads with my hand. The left Bank when looking at the motor from the back of the boat was HOT. The right bank was cool enough I could leave my hand on it. I just replaced the tstats but could water be bypassing and cooling down that side of the block enough to cause that drastic of a difference. I felt all three cylinder heads on that side and they had the same temperature. Thoughts?

[cedlin1234]

Okay. I replaced the Engine coolant temp sensor and the Air Intake Sensor and my idle went up, albeit not more than a few hundred RPM's but certainly was improved. I also did a seafoam cleanse of the engine.

My question remains, Are there any theories on why the right bank was so much cooler than the left bank (looking at engine from back of the motor)?

What else should I be looking at?