Oil reservoir on 1990 250 V6 not filling Head tank reservoir

Twisted28

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#1
I have not been on the site for a while but would appreciate some insight and help if anyone knows anything about these systems.

I will layout the items I have checked and done to eliminate and narrow down the issue.

On my 76 deg V6 1990 250hp 2 stroke motor the head reservoir is not filling up from the main tank.

I started at the main oil tank in the aft bilge and pulled that out, checked the and replaced the inline small filter prior to the pump which was clogged.

I then tested the pump itself by supplying power to the pump leads and it worked.

I jumped to the motor itself and switched the powerhead reservoir float sensors and the CDI units. - no change.

In the main oil tank there seems to be a sensor which goes to the bottom of the tank. I pulled that out and check it. It seems to break continuity if the tank is empty preventing the tank pump from running dry. When the tank has oil in it, the small float lift and creates continuity on the sensor so I think that is working fine.

Checked the four wires from the connector at the tank to the connector at the motor, all good continuity.

at the same connector I checked for continuity between the four leads to the connector plug which feed into the CDI unit - all good

At that connector in the motor which are the four wires coming from the tank, 2 for the tank sensor which creates continuity or breaks it if the tank is empty and a power lead and ground (blue and brown) if at this connector in the motor, I ground the blue wire and have the other three connected, the pump will run filling the power head reservoir.

So this leaves from the reservoir connector to the leads going into the CDI unit which checked OK for continuity.

So the CDI unit was switched, the reservoir sensor cap was switched with the other motor and all continuity checked out.

It seems as though, unless I am missing some relay, all systems are working and the call for oil is being sent out from the cap sensor on the power head reservoir. Somewhere along the line it is simply not getting the signal ground which as stated above will run the pump filling the tank but I can not keep this grounded as it will not shut off when full.

What am I bypassing by doing this. I think it is a call from the CDI unit but like I said this was switched with the working side.

Any help from someone who may know something about this.

Greg[/list]
 
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#2
Not sure about your specific engine model but on some units the tilt/trim lever has to be in the "down" position for the relay to signal it is ok to transfer the oil. If yours is damaged and in the "up" position, it may not allow the signal to work. Does your trim gauge show that it is working? If so, something else has to be stopping the transfer. I think there is a good procedure for checking everything oil related on iboats.com forum under the yamaha section. Good luck.
 

seasick

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#3
I think he is referring to his 2 stroke oil tank not the trim.

Twisted:
Do you have analog or digital instrumentation.
If you have digital, the gauge has bars on the bottom and 'alarms' to warn you about low oil conditions. If they are working correctly, the apprpropiate sensors are working.
If the engine oil tank gets low enough, an alarm should sound, display and the motor will throttle down.

The also should be a manual oil tank pump switch on the engine. Your owners manual for the motor will show you where it is. It is there to allow you to manually pump oil from the main tank to the engine tank without 'grounding any wires. If that works, the circuitry to the main tank and the pump work.
The first task as outlined above is to determine if it is a sensor issue or a pump issue.
I will see if I have any service info for that motor.
 
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#4
seasick said:
I think he is referring to his 2 stroke oil tank not the trim.

Seasick,

I was referring to his oil transfer. Simply put, if the engine is tilted up, oil transfer will not happen. If the small plastic tilt lever is broken the engine may think that it is tilted and will not transfer the oil.
 

Twisted28

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#6
Barlow46 said:
Not sure about your specific engine model but on some units the tilt/trim lever has to be in the "down" position for the relay to signal it is ok to transfer the oil. If yours is damaged and in the "up" position, it may not allow the signal to work. Does your trim gauge show that it is working? If so, something else has to be stopping the transfer. I think there is a good procedure for checking everything oil related on iboats.com forum under the yamaha section. Good luck.
Thank you for the reply. The tlit switch is something I never thought of but they do work. I had actualy replaced one of them earlier in the season to ensure they were working correctly.
 

Twisted28

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#7
seasick said:
I think he is referring to his 2 stroke oil tank not the trim.

Twisted:
Do you have analog or digital instrumentation.
If you have digital, the gauge has bars on the bottom and 'alarms' to warn you about low oil conditions. If they are working correctly, the apprpropiate sensors are working.
If the engine oil tank gets low enough, an alarm should sound, display and the motor will throttle down.

The also should be a manual oil tank pump switch on the engine. Your owners manual for the motor will show you where it is. It is there to allow you to manually pump oil from the main tank to the engine tank without 'grounding any wires. If that works, the circuitry to the main tank and the pump work.
The first task as outlined above is to determine if it is a sensor issue or a pump issue.
I will see if I have any service info for that motor.
I have digital gauges and they are working correctly. The alarm sounds when the head tank is low and reduces the RPMs. The manual fill switch functions and fills it. The pump does work. I had also switched the CDI unit form the other motor to see that was bad. Still does not auto fill the Head reservoir.
As far as being a sensor issue, I had also switched the Head reservoir cap which has the sensor float and still does not auto fill.

So I was thinking it was a connection from either the engine head res to the CDI or from the connection in the motor from the tank to the bottom of the CDI unit. All the wires check out with continuity so I know there is no break.

I am basically stumped.
:(
 
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#8
Just-In-Time has your answer. He can get you the ten minute check sheet to troubleshoot the problem. Get in touch with him.
I was using the wrong terminology when I said "tilt switch". It is actually a "trim" lever that sits on the engine tilt tube. It is a black plastic piece about an inch or so long that signals the tilt attitude to the tach but also lets the reserve oil tank pump know not to pump oil when in the engine tilt up position. I am not real sure but I think that once the engine passes the trim position and moves into the tilt position is when the signal is given.
 

seasick

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#10
Just-In-Time

Thanks for that piece of info. I wasn't aware that the tilt angle sensor also fed the oil pump logic.It makes sense though.
 

seasick

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#12
I always thought that the float in the secondary tank was up even when the motor is tilted as long as there is suffucient oil in it. Next time I have the cowling off, I am going to look at it both down and up.
 

Twisted28

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#14
Just-in-Time, I got the trouble shooting guide and it is VERY informative. Thank you! After reading the guide, I can account for all the tests and check procedures except for the tilt sensor and ensuring the ground it feeds from is good. I did not know this until reading it here from you, Barlow46 and seasick.

Would it be possible for the tilt sender to show proper position at the gauge, yet the sending signal saying it is down, is not being read by the ????

I did find where the main power feed to the motors, had rubbed on the battery charger box. Two thick feeds with one small (ground?) as a ribbon type of cord, where the small wire had some corrosion built up from an opening in the casing. I did splice in a new section of the small wire on Monday. Now depending on the level of the oil in the engine tank and when it calls for it, it may work now but I was testing to see if it worked based on the motors not running, just the key in the ON position.

I will not be down to the boat again till the weekend so any other suggestions are welcome.
 

Twisted28

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#15
Fixed the problem! Many thanks to Just-in-time for the troubleshooting info.

It turns out it was the filter in the remote tank which I had replaced as one of the first measures. It was clogged. While trouble shooting it, I just did not know the sequence and conditions as to when it calls for oil.

If you have a similar issue, make sure the engine is running when the oil in the Powerhead tank is low or it will not fill. I found this to only fill with the key in the on position when the oil hits the lower switch which triggers the alarm, only then will it fill with just the key on.

That is why I kept chasing the issue without realizing I had it fixed.
I took some measurements to help know when the first switch would call for oil.

With the motor tilt about level, the first switch will call for oil ONLY WHEN THE ENGINE IS RUNNING, at 4" below the top of the tank neck or the rubber cap seal of the tank sensor. This put s the level just below the mid way mark between the upper tank mark and the lower tank mark.

I used a primer bulb with some short pieces of tubing to extract the oil during my tests.

Thanks again to all who helps.