No power to electric fuel pump

[fisherpeakhippie]

I have a 2005 Yamaha F90 TLRD that is not getting power to the electric pump in the vst tank. I have replaced the pump and it is working but I can't seem to get power to it. The fuses are good and I have power to turn the starter. I can't see any damage to the wiring but I have not dissected them and don't want to. I'm leaning toward the ecu but don't know. Any suggestions would be greatly appreciated. Thanks

 

[99yam40]

I believe the pump gets power at key on, but the ecu tells it when to rim by completing the negative side.
so, are you getting 12V + at key on?

 

[fisherpeakhippie]

No, used a test light on the connector and got nothing when I turned the key on. Used a battery and jump wires to know the pump is working.

 

[boscoe99]

The ECU does not provide battery power to the electric fuel pump. Battery power is from the fuel pump relay.

 

[Jeff J]

What tells the pump to pump? It should cycle when the key is turned on and I would assume constantly while the engine is running but I don’t know what controls it. I can’t remember if I can turn it on with the YDS.

 

[boscoe99]

The ECU applies the ground to the pump to cause it to run.

Turn the key to the on position and the relay closes. Battery power to the pump motor. Turn the key to the start position and the ECU applies the ground. Motor starts the ground continues to be applied. Motor dies then the ECU disconnects the ground.

 

[fisherpeakhippie]

So it can't be the ECU, right? Then it must be in the wiring harness or relay. Getting closer. Man I didn't want to dissect the wiring. I guess I don't have a choice.

 

[Jeff J]

There is power only for a moment when first turning on the key. If the connector at the VST is dead when the key is turned on then I would backtrack that until I found power.

It could also be a bad ground.

 

[99yam40]

There is power only for a moment when first turning on the key. If the connector at the VST is dead when the key is turned on then I would backtrack that until I found power.

It could also be a bad ground.

why do you think he has only for a moment when first turning on the key?
he never wrote that