150 vmax. No signal to coil #5, or oil tank pump

[boscoe99]

Sigh. I buy them their books, send them school and they eat the pages.

After all else fails, follow the directions.

Go back to the diagram that I posted. Start at the pump. The brown wire at the pump. Work your way back to the motor. The brown wire from the motor connects to a brown wire in the oil harness. The brown wire in the harness connects to a yellow wire on the motor harness.

Look carefully at the diagram. Where does it say that the yellow wire goes to or comes from?

Sigh.

I am guessing that a new CDI is needed. Several of them since the next two or three you try won't solve the problem.

[RobbertF]

whoa whoa whoa.
hold your roll.
the brown wire 12V has NOTHING tpo do with the yellow at the ECU.

the 12V for the brown wire key on power is from a splice about 6" from the 10 pin harness connector.
find the blue oil tank connector,test the brown sometimes yellow engine side to ground at key on.
.

I have a yellow wire on the other side of the brown wire at the blue plug under the cowling. When I unplugged the yellow wire at the ECU and the motor side of the blue plug, I get continuity through the yellow wire. Is there a splice in between sending 12v to the oil pump AND the ECU?

[RobbertF]

Sigh. I buy them their books, send them school and they eat the pages.

After all else fails, follow the directions.

Go back to the diagram that I posted. Start at the pump. The brown wire at the pump. Work your way back to the motor. The brown wire from the motor connects to a brown wire in the oil harness. The brown wire in the harness connects to a yellow wire on the motor harness.

Look carefully at the diagram. Where does it say that the yellow wire goes to or comes from?

Sigh.

I am guessing that a new CDI is needed. Several of them since the next two or three you try won't solve the problem.

I guess I need to do some more wire tracing. As I replied to Rodbolt, I found continuity from oil tank harness to the yellow wire that attaches to CDI pigtail and ASSumed that was the source of 12v key power. Guess I better keep looking.......

[boscoe99]

In a Yamaha the yellow wire is key on power 99% of the time. That is, it is the act of turning the key to the ON position that applies the voltage to the yellow wire.

That power can go to a two stroke remote tank oil pump, the CDI or ECU, the instruments and any number of other places that Yamaha decides it should go.

[RobbertF]

In a Yamaha the yellow wire is key on power 99% of the time. That is, it is the act of turning the key to the ON position that applies the voltage to the yellow wire.

That power can go to a two stroke remote tank oil pump, the CDI or ECU, the instruments and any number of other places that Yamaha decides it should go.

I really appreciate the help. Sounds like I am missing key power to the whole motor if I do not have it at the pump harness and CDI.

[99yam40]

whoa whoa whoa.
hold your roll.
the brown wire 12V has NOTHING tpo do with the yellow at the ECU.

the 12V for the brown wire key on power is from a splice about 6" from the 10 pin harness connector.
find the blue oil tank connector,test the brown sometimes yellow engine side to ground at key on.
.

just checking to see if the OP missed what Rod wrote about the splice.
need to find that slice, as they corrode and lose connection sometimes

[rodbolt17]

the oil pump AND the CDI require 12V to work correctly.
cyl 1&4 and cyl 3&6 fire by a pulser coil signal(trigger).
cyl 2 and 5 trigger based on crank position signals.

with no 12V the ECU cannot work correctly and typically ign timing is fixed and cyl 2 and 5 quit.

with no 12v from the keyswitch there wont be any oil transfer.

[RobbertF]

the oil pump AND the CDI require 12V to work correctly.
cyl 1&4 and cyl 3&6 fire by a pulser coil signal(trigger).
cyl 2 and 5 trigger based on crank position signals.

with no 12V the ECU cannot work correctly and typically ign timing is fixed and cyl 2 and 5 quit.

with no 12v from the keyswitch there wont be any oil transfer.

That explains a lot. I am going to chase that 12v key power. I thought it came from CDI pigtail TO oil pump. It distributes from another location to both.
Thanks so much.

[boscoe99]

Disconnect the main ten pin coupler in the front of the engine pan. Find the terminal for the yellow wire on the boat harness side. Turn the key on. Check the pin for the presence of 12 volts. Not the pin shown in this illustration. The one that it connects to and runs up to the dash.

[RobbertF]

Found it!!!!!! The cable that runs back from the 10 pin connector Boscoe posted

In the cable that runs between boat and motor it was broke inside the sheathing at the cowling clamp. Actually no sign of it being broke except there was no continuity from plug to plug. I cut the sheathing thinking it might be a weak spot and saw the kink in the wires. Probably 16 years of raising the motor up and down to trailer the boat finally took it's toll. Now I need a new cable.

Thank you all for your help.

[boscoe99]

Thanks for the feed back. Glad you found the problem. Broken/chaffed wires embedded within harnesses can be a bitch to find sometimes.