04 Yamaha 225hp High pressure pump not turning on

frustratedboater

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2004 F225 TURC 4-Stroke Outboard.
I'm trying to figure out where my high pressure pump relay is on this motor and possible reasons to why I'm not getting fuel pressure on key switch. I have both new pumps both low and high replaced when I rebuilt the VST, replaced trigger, stator is within ohms readings and replaced the rectifier/voltage unit. I did purchase a new harness due to my old one that had corrision issues on some of the plugs.
In my manual I included a pic of the wiring diagram that shows both pump driver & relay but can't seem to locate either in my wiring. Does the driver play a role in fuel management? Is there a way to test the diodes? Any wisdom would be appreciated. Been chasing this for a long time and would realy love to hear this motor run.
 

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frustratedboater

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Thank you for the images. My book doesn't have that pic.. So, I'm assuming that the driver (which seems to be the brains of the fuel operation) can't be tested to see if that is the fault, is there a procedure? It's not a cheap part and just to be sure.
 

boscoe99

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What service manual do you have?

There is not much in the way of a testing procedure. But this is not rocket science and you should be able to come up with something on your own.

First things first. Do you have battery power to the driver when the key is on? On the red/yellow wire.

Do you have a good ground to the driver? On the black wire.

Do you have continuity on the wires from the driver to the ECU?
 

boscoe99

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Where did you get that document? Looks like it is more applicable to a Mercury 225 four stroke (made by Yamaha) than for a 2003 Yamaha F225TURC.
 

frustratedboater

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Yes, I do have 12.9v. at the red/yel wires from the plug to driver. Very strange thing, while checking this and plugging back in I heard the pumps run. hooked up water and it started up!
I seem to be getting an intermitten fail though. It was just idling then quit. Bumped the key and a click was heard with pump activation.
This morning I was dignosing my starter relay and bypassed the the other side (large brown to the small/right side) of the relay and it started. Posibile relay issue, or failing relay?
 
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frustratedboater

Chief Petty Officer
Joined
Jul 10, 2007
Messages
413
Where did you get that document? Looks like it is more applicable to a Mercury 225 four stroke (made by Yamaha) than for a 2003 Yamaha F225TURC.
Are you refering to me, or the images? My source(SELOC 4-stroke 1995-04 Mercury/Yamaha)
 
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