How to "re-install" deleted oil injection system?

[zenoahphobic]

Yes valid point, there will always be a possibility that straight gas unthoughtfully put in.
As I said, you could put a little two stroke oil in the main tank, press the little switch to see whether oil is transferring, but check there is an oil line going from one tank to the other. If it does transfer then you need to confirm the engine oil pump works by running the engine and removing a hose from it to see if oil pumps out. This obviously will be a very small stream.
At that point if that test fails, your pump and as Yam44 said, possibly the drive gear is damaged. At that point I would remove pump and check for the physically obvious.
If you think oil is coming out, without the sensor assembly, you will find it difficult to fault find further, as there is the alarm and limp mode consequences. Not essential but handy to have that system working also. With a new sensor module, of course you can assume the system will then work.
You can always have a half measure, that is, if your pumps work, you manually transfer (via switch or even physically) periodically fill the engine oil tank. You will get some distance between fills but you need to monitor it. I had a 115 where the oil system failed. It never stopped pumping oil to the point the engine could hardly run from the oil diverted into the throats of the carbys . A short term measure was to electrically isolate the system to stop the pump from continuously running, so I could use the boat. I never fixed the system it was not that inconvenient to press that switch now and again (went with flushing maintenance, or refuelling times).

Or if you don't want to mess with oil at this stage, I would go straight to the engine mechanical oil pump and pull it to ascertain whether it is OK, and then if needed, whether the costs of it and the missing sensor are worth it.

[bigdummy]

So seems best to start at remote oil tank and work my way from there.
Will I need the cap/sender(?) that is missing from engine oil tank or will the switch on the motor allow remote tank to run?

Motor and rigging have been removed from boat . Seems I should have run the diagnostics before unrigging. Live and learn. Time to get started "rigging" the motor to see what I've got.

Thanks again for the advise

[99yam40]

I myself would start by checking to see if the oil pump drive is in place om motor ,
along with if the oil pump and all oil lines are in place.
then see if the remote tank still has the pump,filter and lines in place.

check for wires to the pump and power to that electric pump when you turn the key on
then try to find out what was done to the wiring on motor to bypass the float switches .

[bigdummy]

Everything "appears" to be in place (I'm very familiar with Mercury, not so much Yamaha). Remote oil tank does have pump and oil line was hooked up to motor.
I quickly" traced oil lines on motor and didn't see any cut/capped lines- but again- I didn't spend a lot of time searching.

The wiring harness from the tank was still connected to the motor harness, however I cannot recall whether to was connected at the tank.

Still curious "how" the motor runs without oil in either tank (I'd think motor would be in safe mode- the only Yamaha I ever had before this would go into a safe mode when the oil level got low)

[99yam40]

apparently someone has modified the wiring to make that happen.
you or Someone will have to look to see what was done

[boscoe99]

You are correct. When the main engine mounted oil tank gets low a switch in the sensor assembly closes. The motor then goes into RPM reduction mode, the horn sounds, and if certain Yam instruments are installed a red light or low oil icon will flash.

Point of note. It is not a safe mode. If the motor continues to run when the warning horn is blaring it can be damaged. As in it will be toast.

[99yam40]

so called safe mode is reduced RPM but not a dead motor, so you can still maneuver the boat out of harms way hopefully.
But it does not protect the motor in any way

[rodbolt17]

actually D was used twice.
once in 1990 and again for 2005.
do some forum searching.
I have flogged PBS like a dead mule over the years.\
the 1990 system uses the trim sender for oil control.
the 05 uses the pulser coil input.

[walleye1]

That is what screws up test takers at yamaha that don't work on the shit every week.

[rodbolt17]

and then some early 225 HP motors in the mid 1990's. some were 2.6L and others of the same year and HP were 3.1L. two vastly different engines.
Volvo's alphabet soup is somewhat more difficult than Yamaha's.
that is why I do not like the current ONBOARD rag and prefer the old MTG.

[boscoe99]

And then some early Yams used a Mercury sensor/switch to control the automatic oiling system.

Two strokes were phased out before Yamaha could implement a fourth and fifth way of con*****ing the automatic oiling system.