Yamaha OX66 help needed

GreatWhite23

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I have had a ongoing issue with my new to boat repower. Here is the skinny, runs for a hour or two hit a wave hard starboard alarm goes off and powers down. Checked oil res. almost empty manually filled it. Alarm gone. took it to a marina to have the once over ,replaced fuse box and several other electrical issues. Took it out all good 3 hours alarm goes off again. Oil res. is full i take cap off res. off we go. It is peeing just fine. Told it had new water pump. Did not feel hot. It is smoking more than usual when trolling. Could it be a failing oil pump in res? Any help would be very appreciated. No signals on tach off any issue. Could it be starving for fuel changed from 150 twins to 225 twins???
 

GreatWhite23

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Forgot the power trim sometime goes crazy then will not respond. I lost confidence in marina when I explained issue there response was it could not be brought back to there shop it had to go to employes house to be worked on. They would be happy to fix it though
 

seasick

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The powering down sounds like the motor is going into safe mode. It will do that when the oil level in the engine (main) tank gets to the low position. Did you manually fill the engine tank? How so? With a can of oil or did you use the manual fill toggle switch. That info will help diagnose the issue
 

GreatWhite23

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I filled the res manually using the switch(could hear the pump running) I am thinking of replacing the oil filter,thermostat, taking heads off and cleaning them,new water pumps, and something else plusreplacing low oil switch.(i think this is my issue). Fresh water flushed today no water coming out starboard motor. Ran compression check on cylinders all at 105.(just checking before going further with motors)
 

grady33

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Do you have a remote oil res? Those remote oil pumps don't last forever.
 

GreatWhite23

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yes It does have a remote oil res. I was told that if you could hear the pump working when manualy filling it was good? The previous owner had the same problem with the 150s same side. (lead me to think it was the pump)My only issue is that the res was full on Saturday when the alarm was going off. Pulled the cap off put it back on ran for 3-4 miles and alarm off. restarted it three times made it back to the boat ramp another 3-4 miles. Checked oil res it was full again.
 

seasick

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GreatWhite23 said:
yes It does have a remote oil res. I was told that if you could hear the pump working when manualy filling it was good? The previous owner had the same problem with the 150s same side. (lead me to think it was the pump)My only issue is that the res was full on Saturday when the alarm was going off. Pulled the cap off put it back on ran for 3-4 miles and alarm off. restarted it three times made it back to the boat ramp another 3-4 miles. Checked oil res it was full again.
The alarm is not triggered by the level in the remote tank. It is triggered by the level in the main (engine) tank.
Since you can use the manual feed to fill the main tank, the pump is OK. The filter could be partially clogged though. If that is the case, the filling can't keep up with the consumption and at speed and load, the main tanks eventually runs low.
The next time you get the alarm, shut off the ignition and remove the motor cowling. Note what the oil level is in the main tank, it should be low. Turn on the ignition and see 1. if the pump in the remote tank runs and 2 if the main tank is filling. If filling, see how long it takes for it to fill and note that also.

Ig the alarm goes off and the main tank is not low, you have a bad main tank sensor, bad harness or most unlikely a bad ECU.

Note that if the ECU thinks that the remote tank is low/empty, it won't switch the pump on. So if the remote has oil but the ECU doesn't think so, you have a bad remote sensor, bad connection/harness or again bad ECU ( unlikely).
The alarms indicated on the gauge (digital or analog) should tell you what the state of both tanks is. Make a note of all the indications also when the alarm occurs.
In rare cases, the wire harness that connects the remote unit to the motor gets a fracture where it passes though the grommet. Touugh to find that one.
 

GreatWhite23

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Thanks I am going to replace res sensors I think this is a good place to start sense the res was full on Sat when the alarms went off. I also ordered new head gaskets, thermostats, water pumps. poppet valve. Going threw the cooling system would not hurt sense i have not owned the motors long. Hitched fresh water flush no water coming out of stb motor. Thinking heads might be corroded or clog somewhere.
 

seasick

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GreatWhite23 said:
Thanks I am going to replace res sensors I think this is a good place to start sense the res was full on Sat when the alarms went off. I also ordered new head gaskets, thermostats, water pumps. poppet valve. Going threw the cooling system would not hurt sense i have not owned the motors long. Hitched fresh water flush no water coming out of stb motor. Thinking heads might be corroded or clog somewhere.
It is important to note which res was full, the remote (the big tank) or the main on the motor. It could be a big waste of money to replace both sensors if it turns out that you need a new $17 filter on the remote tank.
Get a hold of a service manual, there are detailed instructions on checking the functionality of the sensors.
 

GreatWhite23

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What I have been told is that if your remote sensor goes bad your warning lights will flash. If your main goes bad it will not set off the alarms on the tach? 9 times out of ten your main is the one to go bad(info from yamaha tech)Been researching alot and greatly appreciate everyones impute.
 

seasick

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GreatWhite23 said:
What I have been told is that if your remote sensor goes bad your warning lights will flash. If your main goes bad it will not set off the alarms on the tach? 9 times out of ten your main is the one to go bad(info from yamaha tech)Been researching alot and greatly appreciate everyones impute.
I don't know what was told to you but the main sensor has three switches, the high, medium and low.
Triggering of the medium tells the oil pump to pump.
Triggering of the top or high, tells the pump to stop.
Triggering of the low causes an alarm. so...
If the top sensor never triggers, the tank will overfill.
If the middle sensor never triggers, the ECU will never call for oil.
If the bottom never triggers, the motor MAY run out of oil but as long as there is oil in the remote tank, nothing will happen assuming the pump can keep up with demand which is the normal case.

The sensor on the remote tank has only one contact, the low oil warning. If that is triggered, you get an indication on the gauge and the ECU will not send the signal to pump oil even if the main tank needs oil.
All of these conditions are quite easy to test without any tools.
 

steveg

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Had the same problem, removed the main oil tank, replaced the filter with a new one and all problems went away. Steve
 

GreatWhite23

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Thank you for the help. I did get a new filter and pump sensor for both tanks. It might not need then but when we head for Florida for thanksgiving week I want it fixed. The sensors were alittle over ahundred dollars a piece. Buy the time I take it to water run it for three hours I have gone threw gas and time. (fixing it with everyones help also saves some green)Plus from what I hear the sensor in the main tank goes out regularly any how (they are 12 yrs old) Nothing worse than getting out there and having to go home over a couple hundred dollars in parts.
 

GreatWhite23

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Ok I think it is possible the wired the keys wrong when they installed the motors when I tilt one motor up the other kicks in goes down the motor runs down constantly until I go back and use the tilt on the motor then it seems fine and operates how it should. They did say that they had the same problem last time they switched motors. What would be causing the tilts to malfunction, It might be time to take it to a marina, I tried this two weeks ago and got a 2,431.00 bill for filling the oil res. switching the fuse box, replacing tank float, wiring new navigation(Garmin 740s) :shock: does anyone know of a decent marina in NC???
 

Andrew93

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It might be worth checking the trim sensor one the bracket of the engine. The remote oil tank will not fill the main tank if it senses the motor it tilted up, so even if the pump works it will not call for oil. The lights on the dash work off a ground side switch, I had a problem with the wire going from the motor to the gauge, but it doesn't sound like this is your case since you are getting readings, mine was stuck on the yellow light when the wire going to the gauge was damaged.

You can jump everything and test it's operation with 1 or 2 pieces of wire, the service manual has a good description on how to do it if you have it. Sounds like the oil system is working as it should though and it might be that trim sensor where you said the trim has been acting up anyways.

PM me if I can help any more

Andrew
 

GreatWhite23

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Been working on the boat today. Noticed that the stb gauge is showing empty when oil tank is full. Sometimes showing up to 1/2 never full. replaced res oil tank sensor. which sensor does the gauge read??? Also switched thermostats put ears on no water peeing both thermostats are open. lower unit is stuck and will not come off.(banged on it with rubber mallet then larger block of wood) Checked other motors pump it is brand new. I bought a manual on ebay my apple computer does not like it :bang . Still thinking I can replace a whole lot of parts before I get another 2+ bill. Also thinking it might not be a bad idea to hire a professional. I am mechanically inclined and need to learn about outboards if I am to have a older boat...So off we go into a lesson of frustration. Less to go wrong done the road any how
 

seasick

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GreatWhite23 said:
Been working on the boat today. Noticed that the stb gauge is showing empty when oil tank is full. Sometimes showing up to 1/2 never full. replaced res oil tank sensor. which sensor does the gauge read??? Also switched thermostats put ears on no water peeing both thermostats are open. lower unit is stuck and will not come off.(banged on it with rubber mallet then larger block of wood) Checked other motors pump it is brand new. I bought a manual on ebay my apple computer does not like it :bang . Still thinking I can replace a whole lot of parts before I get another 2+ bill. Also thinking it might not be a bad idea to hire a professional. I am mechanically inclined and need to learn about outboards if I am to have a older boat...So off we go into a lesson of frustration. Less to go wrong done the road any how
What gauge are you referring to? Tell us what you see exactly. The gauge doesn't display the level of the remote tank. It tells you if the tank is low or not. Do you have an owners manual for your motor?. No a service manual, an owners manual.
 

Andrew93

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Did you make sure yiu got the bolts under the cavitation plate. There is one under the zinc and there might be 1 or 2 more from memory making 8-9 total.

I can scan you some pages out of the service manual too to rule the float switches out.
 

seasick

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Fire93Medic said:
Did you make sure yiu got the bolts under the cavitation plate. There is one under the zinc and there might be 1 or 2 more from memory making 8-9 total.

I can scan you some pages out of the service manual too to rule the float switches out.

I think it is seven bolts. You have to remove the trim zinc. There is a bolt under it.
 

GreatWhite23

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Yes got all the bolts stb came off easy, I have tried for to get the port lower unit off might take some heat. She seems to have several issues I am taking her to the doctor tomorrow. If I had more time I would like to fix her myself. Got busy at my job no down time until after christmas. I bought a manual from ebay it sucks....I will post what it took to fix her. There seems to be oil leaking out the side of the lower unit also.(out the exhaust and side Thank again for all your help :)