2004 Yamaha HPDI 250hp - Oil not pumping into tank under motor cover

[dbassman]

The oil will not pump from the 2.5 gallon tank in the boat any longer. The pump in the tank pumps when I energize it but nothing is telling it to pump. Float inside small tank under motor cover is working. Any help please?

[yam911]

The engine mounted tank is the main oil tank. The boat mounted tank is the remote or auxiliary oil tank.

For the automatic transfer system to function the boat mounted tank has to have a certain amount of oil in it. If the remote tank is low on oil the automatic transfer system will not function. IF THE ECU THINKS THAT THE REMOTE TANK IS LOW ON OIL THE AUTOMATIC TRANSFER SYSTEM WILL NOT FUNCTION. Even if the remote tank is full of oil.

There are wires that run from the motor to the remote oil tank. With connectors. To a switch in the remote oil tank. Any thing wrong with the wiring, the connectors or the switch will cause the ECU to think that there is not enough oil in the remote tank.

Start by inspecting the wiring and the connectors to and from the remote oil tank and the motor.

[dbassman]

So I was told the ECU was not telling the pump to kick on in the remote or auxiliary tank. So the float or switch inside the remote tank must be bad. How would I test this switch/float?

All wires and connections look good. I unplugged all connections cleaned them and plugged them back together.

[WayneM1946]

You might want to replace the filter in the main oil tank (on the side of the motor) as well and clean that tank out. If that filter gets stopped up, oil from the remote, aux tank in the bilge cannot into the main tank.

[yam911]

The test for the remote oil tank sensor switch is simple and easy. Remove the sensor assembly. With the float up there should be continuity between the two wires. With the float down there should be no continuity between the two wires.

Float up, switch closed. Float down, switch open.

[dbassman]

Ok. So I removed the float in the remote oil tank and it checked out good. Then I drained the remote tank and the main tank and cleaned them out. Changed the small filter at the bottom of the remote tank too.

Hooked everything back up and added oil to the remote tank. Turned on the key and the buzzer went off and the pump started pumping (while the buzzer was going off) when the oil level in the main tank got to the upper/full mark the pump stopped but the buzzer continues to sound. Turned key off to try to reset buzzer but now the buzzer will not shut off with the key in the on position. Where do I go from here? What should I check now? Thanks.

I have not tried to start the motor yet also?

[yam911]

The main tank sensor assembly has three switches. Top, middle and bottom. The bottom switch closing tells the ECU to sound the alarm and to put the motor into the RPM reduction mode. If one starts with the main tank empty the switch is open. That is why the alarm is sounding. The alarm should have stopped when the tank was about a fourth filled.

Only thing to do is to check the bottom switch and the wiring to the ECU.

But starting the motor is free. No harm is doing that. Try it and see. I don't see it stopping the buzzer but what the heck. Give it a go.

[dbassman]

Is it possible that the problem is in the ECU? It will only pump oil back into the tank if I drain the tank and turn the key off and back on. Then it will pump oil back into the main tank to the top line.But alarm continues to go off. How do I check the float switches in the main tank?


Update:

If I leave the key in the on position and drain oil from the main tank it does not kick on the pump and the tank will drain empty. Once I shut the off the key and turn it back on it will pump oil to the top mark on the tank. So as the motor uses oil the pump does not kick on to replenish the tank. It will only kick on when the tank is empty and I reset it by turning the key off then back on.

I'm confused.

[yam911]

Is it possible that the problem is in the ECU? Possible but not likely. It will only pump oil back into the tank if I drain the tank and turn the key off and back on. That is the way that it works.Then it will pump oil back into the main tank to the top line. But alarm continues to go off. That is the problem. How do I check the float switches in the main tank?

Update:

If I leave the key in the on position and drain oil from the main tank it does not kick on the pump and the tank will drain empty. That is the way that it works. Motor has to be running for the automatic transfer system to function. Once I shut the off the key and turn it back on it will pump oil to the top mark on the tank. That is the way that it works. So as the motor uses oil the pump does not kick on to replenish the tank. It will only kick on when the tank is empty and I reset it by turning the key off then back on.

I'm confused. You and most of the Yamaha mechanics.

To check the float sensor it has to be removed from the main oil tank. Then bench tested using a continuity check. See below:
zfloat.jpg

[dbassman]

Checked continuity on all three ABC. All seem to check out. Alarm continues. I will start the motor tomorrow to see if the automatic transfer function will work. While the motor is running I will drain oil from the tank and see if it pumps back into main tank.

I need the alarm to stop?????

[dbassman]

Started motor today and drained oil from main tank while running. The alarm was going off continually while it was running. No oil pumped back into main tank. Installed new float in main tank that I got in today. No change. Im Stumped. Where do I go from here? Help!

[dbassman]

It's going into the shop next week. Thanks to everyone that tried to help. I really think its in the ECU. If so this one is not going to be cheap.