Yamaha '91 115HP 2 strk oil transfer problem.

[Kartoffel]

I couldn't find a topic exactly like this one and I'm stumped on my issue summarized below.

Running normally buzzer sounds, open engine, see low oil, remote tank nearly full, emergency switch oil transfers up to top. Restarted engine fine rest of the day but I didn't go far enough to auto fill again.

Back at slip, I did some testing. My tach has the 3 led display with red, yellow, green items for oil. When i key on all three arrows flash, it goes green for 5-10 seconds then yellow. This means remote tank is low, but it's not. Explains why it is not auto filling remote tank. I dismantled remote tank fill switch and cleaned it. Slides freely and tested with multimeter. Continuity when in tank. Tested blk and black/red wire at engine entrance where it plugs to first harness and same continuity. Also jumped matching wires on female engine side and tach stays on yellow light.

I can't find where blk/red wire goes further upstream.

Also the pump doesn't run when i turn the key on. I'm pretty sure it used to for 10 sec or so

My question is this

Could the tach be in error? Red/buzzer seems to work fine, but i never paid attention to it before. I'm sure oil transfer worked last season.
Where does tach get signal from? The oil control module with the emergency switch?
Is that module the problem? I hate to spend $250 and find it is something else. Any ideas what else it could be?
Is that a plug and play part with no tuning?

Also my trim sensor works fine and shows full down. Should not be related but i see many people saying to check this.

Thanks

[boscoe99]

A yellow light means that the boat tank is low on oil. OR, that the motor thinks that it is low. Why would it think this? Because the oil module does not detect a ground source from the boat tank sensor. Could be the sensor switch or it could be wiring. You say the sensor checks out. So,

Verify that the black wire has continuity from the block all the way to the sensor.

Verify that the black wire with a red tracer has continuity from the sensor back to the motor side connector.

Then you will need to check for continuity from the motor side connector to the oil control module. Unfortunately, Yamaha does not maintain consistency with wire colours. What wire colours do you have in the connector that goes to the oil control module? Do you see a green wire with a black tracer? That may be the wire that is connected to the black wire with a red tracer somewhere within the engine harness. Check it for the presence of a ground reference when the remote tank float switch is up.

[Kartoffel]

Thanks. I will try tomorrow. Are there any tricks of the trade to measure continuity over that distance singe handedly? It's hard to hold the meter probe on the pins far apart.

[rodbolt17]

the trick?
its called jumper leads with alligator clips.
radio shack is your friend.
there are some splices in the engine harness that can fail.
your looking for the black engine ground and the black/red oil control module path.

[submariner47]

interesting info

First I am new to this , so if I ask a dumb question, humor me. I have a similar problem with a 1993 200 2 stroke. I thought I had figured it out but now have doubts. I had thought it was the oil gauge assembly not sending a low signal to the pump.

1. is there a way to emergency transfer oil from the remote tank to tank on the engine?
2. Seems I should get goods manual to understand the instrumentation and motors- Suggestions?

Thanks for any help given.

[rodbolt17]

the original post was about a V4, the V6 is slightly different since 1990.
start a new thread or it will get confusing.

[submariner47]

ok

I will start a new one ed

[boscoe99]

Data from the service manual for your specific model is worthless with respect to tracking down wires and such. Here is data from a 2003 model year 115 Yamaha that will provide a basic understanding of how the wires and components are connected to one another. Plus, it is now in colour. Colour is nice.

[Kartoffel]

Ok. Problem found. As you said Boscoe. The black ground wire is cut somewhere in the main harness. The signal makes it up to first connector from the tank. I was able to find all the other wires were continous. Blk/red went to green/blk

So my question is this, to avoid spending $300 on a new harness, i am tempted to just splice in a wire next to the main harness? Hopefully the problem is buried in the harness and.not at the connectors. If there is a bad splice deep within the harness would something else be likely to fail later? (I'm asking this because its clear Boscoe and rod know better whats going on in there than i do)

Edit: i didn't see update with color graphic. What is the vertical red, black, grey/black wire? Just curious if the splice is bad that could fail too, which was my above question. Thanks again for help


Thanks for the help.

[boscoe99]

The main harness is the harness that is wrapped around the motor. The oil harness is the one that connects to the main harness and then runs from the motor to the remote tank sensor/oil pump. Please clarify which harness has the broken ground wire. From your description I cannot tell.

However you need to get a good ground to the oil harness then go ahead and do it. Splicing is fine by me. If it is good enough for Boeing, Delta Air Lines and the FAA then it is good enough for me.

I like to use a crimped butt connector, soldered carefully, followed by heat shrink tubing over the connector. Don't forget to slide the heat shrink on first. Don't ask me how I know about this.

[boscoe99]

Edit: i didn't see update with color graphic. What is the vertical red, black, grey/black wire? Just curious if the splice is bad that could fail too, which was my above question. Thanks again for help

Those wires go elsewhere and have nothing to do with the oil system.

[Kartoffel]

Ok the reason I asked about the other wires is incase that black was separated but seems like it has a ground connection upstream anyway.

The break is in the main harness inside the engine. The one in your first diagram along the bottorm with all the wires.

[boscoe99]

If I understand you when you disconnect the oil harness from the main engine harness, and you test the ground wire on the engine side connector, you are not seeing ground. Is that correct?

Does the black wire pin in the engine side ten pin coupler have a good ground?

Both pins share the same ground source.

[Kartoffel]

Update. Went from bad to worse.

The ground wire in the main harness was broken at the umbilical connector, right at the pin. I spliced in a new wire (had to modify the 4 wire oil tank wire as well, used a heat shrink snap plug) and I get continuity all the way from the remote oil tank connector to the big oil pump control module connector (in your drawing "From remote tank sensor switch"). This is clearly an improvement as the ground was severed before. Checked continuity for all 4 wires in the bundle (blue, brown, black, BR/GB) and it's good.

Setup to run, turned key on, same issue, stuck at yellow on tach, Rechecked connections, everything is good.

Rechecked continuity on 4 wires all are 0 Ohms, very solid.
Checked for any shorts, none I could see.
With everything hooked up I checked the continuity across B and G/B on the oil pump control module connector and it is 0 Ohm and goes to open circuit if I lift remote tank sensor/switch out of the tank. Works perfectly.

Now here is the worse part. Neither the emergency switch or the alarm works any more (lift sensor/switch out of main tank), I'm certain these worked before. If I disconnect the repaired ground wire, it still doesn't work.
Went through checks 2-3 times more, nothing seems out of place.

Now I'm really frustrated and taking a lunch break.

[Kartoffel]

Checked back of tach. Have continuity for blk all the way to the oil control harness. My oil level meter has a green and green/red wire those trace all the way back as well. Green changes over to grn/blk. The other wires are yellow and don't reach the tach. (The tach plug has blanks on its harness side)

And with everything hooked up to back of tach there is 0 ohm between ground blk and the green wire. I don't get it. It has to show a full tank.

Also applied 12 v to blue brown wires at oil module and pump runs. Switch and alarm are still dead. Arghhhhh