Yamaha 70 Oil Injection Question

[hevysrf1]

I am replacing the oil injection lines on my 1992 Yamaha 70, and I'm not sure about the orientation of a check valve. I have the factory service manual and have scanned the page, but the printed arrow is illegible.
Anyone have experience with this system? This is different from most I have seen, as it does not have a bleed screw.

[TownsendsFJR1300]

If you go to this parts site, you can blow it up a bit;

1992 70TLRQ Yamaha Outboard OIL PUMP Diagram and Parts Part #11(x 3, I assume)

I would think you could only blow with your mouth (and get flow) in one direction in the valve. That direction should be the same as the oil would flow..

Hope that helps..

[hevysrf1]

The check valve operates fine, but I'm not sure which direction it should go, towards the pump or towards the tee that feeds the side and bottom of the tank. . The best enlargement I can get from my service manual seems to show flow to the top of oil pump. But I believe it was pointed towards the oil tank when I disassembled it. I'm not sure of its function, but it seems to me that flow should should be opposite of what the manual shows.

[TownsendsFJR1300]

Common sense would be the flow would go from the oil tank to the Carbs...

OR the direction of the oil flow


From the above link, blown up;



If you click on that link in post #2, you can blow up the pic further, move it around, etc..

[hevysrf1]

Well, I believe that it is not the feed line, there is a separate line that comes off the bottom of the tank that supplies the oil to the bottom of the pump. Then 3 other lines supply the carbs.
This mikuni pump does not have a bleed screw, and this check valve, tee, hose arrangement off the top of the pump takes it place in removing air .

[TownsendsFJR1300]

Someone else will have to chime in.

Boscoe or Rodbolt should be able to clarify for you. Just be patient till one of them reads this..

[rodbolt17]

its not hard, follow the arrows.
or the yellow brick road.

[hevysrf1]

its not hard, follow the arrows.
or the yellow brick road.

I replaced the oil lines and did not photograph before disassembly because I have the service manual.
I can't be sure of the direction of the arrow due to poor quality printing in the service manual and poor resolution in pdf.
Is the mikuni pump like a diesel fuel pump where the excess is returned to the tank thru that line with the check?

[rodbolt17]

yes the system is self bleeding with the excess returning to the tank.
the check valves have flow indicating arrows embossed in the plastic.
it is recommended after pump service to run the next 5 gallons of fuel at 50/1 premix to insure the system is working.

[hevysrf1]

Finally found a pic of the check valve and its direction. Unfortunately upload lost much of the resolution, looks like correct direction towards the tee fitting, flow away from the top of the pump.

[rodbolt17]

that's the beauty of FLOW arrows.
they typically POINT in the direction it FLOWS.
same as the yellow brick road went towards OZ.