Yamaha OX66 stalling

[Maxxblade]

I have a Yamaha 2002 OX66 225 hp that just stalls abruptly and will not start. When this happens the high pressure pump is not spinning up when I turn on the ignition. After it sit a while, no set amount of time, sometimes 10 minutes sometime several hours, I will spin up on turning on the ignition and run perfectly. I have changed all filters and unplugged and cleaned all muti-connectors under the cover. any body have ant insight?

 

[99yam40]

Re: Yamaha OX66 stalling

You need to be testing to see if the power to it is going away or ground is going away.
Also make sure the voltage is not dropping low and that the amps it is pulling is not too high while pump is running

 

[Maxxblade]

Re: Yamaha OX66 stalling

when the motor is running there is 12v going to the pump. When you just turn the key on and it spins up there is 12 volts there and after the pump turns off there is no voltage showing, this is all with the motor no running but the key switched on.

 

[99yam40]

Re: Yamaha OX66 stalling

How are you testing ?
Are you loosing the + or the -

How many amps is it drawing while running?

 

[Maxxblade]

Re: Yamaha OX66 stalling

I'm checking the power terminals on the pump itself with a meter. How do I check the amp draw?

 

[jeffersondodson561]

Re: Yamaha OX66 stalling

I would check your fuses, you have a 20 and 80 amp fuse and by check replace with good ones. Usually you could go between the spade fuse on other motors and isolate the component. I usually use a high current shunt to check amps. If you have a voltmeter I think you have to set it to 20 amps dc and take off the negative lead off the fuel pump and put the black on that and the red lead on the fuel pump connection.
The one thing I don't like about Yamaha is that they don't list the amp draw under specifications. But a Mercury approximately the same pressure is about 4 amps. Also test the fuel pump resistor should be .53-.57 ohms. I got a feeling your going to need a manual...

Merry Christmas everyone...
Dear Lord Baby Jesus, I want to thank you for this wonderful meal, my two beautiful son's, Walker and Texas Ranger, and my Red-Hot Smokin' Wife, Carley...

 

[99yam40]

Re: Yamaha OX66 stalling

A DC clamp on amp meter is another way to check amps.

By testing voltage from the + side of motor to motor ground will tell if you are loosing power to it ( should have power as long as key is on)and testing from the negative side of motor to ground when it stops running but is suppose to be will tell if the ground is being lost.( if you read 12 + while the motor is suppose to be running will indicate there is a loss the ground)

Merry Christmas everyone

 

[Maxxblade]

Re: Yamaha OX66 stalling

When I just turn the key and do not start it it shows 12 volts from the + to the -. When the proper pressure is reached and it turns off there is 12 volts at the positive side if
I check it against a common motor ground but show 0 volts when I check between the motor + and -. Does that mean that the regulator in side of the float container somehow cuts the ground and thus the current flow
to the pump. I went out and ran it for and hour and couldn't get it to stop. I will be taking it out again tomorrow so it's a little weird but, Wish me luck that it will breakdown.

 

[99yam40]

Re: Yamaha OX66 stalling

It is not that the pump is up to pressure , the ECU just runs pump for a few seconds if motor is not turning, to prime and pressure the system so when the motor turns over the injectors can squirt some fuel.
It the ECU sees the motor is turning it will keep pump running, ECU controls the ground from what I have read. If it is pulling too many amps it could hurt the ECU I believe.


Definitely need to pick up a Yamaha service manual if you plan on working on this thing yourself or do a lot of forum searching and reading

 

[Maxxblade]

Re: Yamaha OX66 stalling

Thanks for the info. Do you know where I can get a service manual that will not break the bank?

 

[99yam40]

Re: Yamaha OX66 stalling

Look the one you need up on Yamaha site and punch that # into your search engine to see what all it finds

 

[Maxxblade]

Re: Yamaha OX66 stalling

Look the one you need up on Yamaha site and punch that # into your search engine to see what all it finds

Sorry for the delay, Seasonal business.

I got it to do it again and when the motor does not start and the pump does not spin up there is no voltage going to the + side of the HP pump. I jumped a wire and spun it up, turned the motor over while it was spinning and it did not start. I also disconnected the kill switch.

 

[99yam40]

Re: Yamaha OX66 stalling

What do you mean by disconnected kill switch?

Need to find where the 12 + is being lost going to the pump. Should be there anytime key is turned on

 

[Maxxblade]

Re: Yamaha OX66 stalling

The kill switch with the tether or lanyard to kill the motor if you fall overboard. Does the power to the pump come from the ECU?

 

[99yam40]

Re: Yamaha OX66 stalling

Did you just pull the lanyard off or did you disconnect some wiring?

12V + should be from switch or relay not ECU. ECU should control the negative side to tune pump on and off

 

[Maxxblade]

Re: Yamaha OX66 stalling

I disconnected the kill switch from the ignition since completing connection is what stops the motor. Where is the relay so I can check it. How do I test the ignition switch?

 

[Florida Tim]

Re: Yamaha OX66 stalling

I Just found this forum but this happened to us today. After a day of tracing potential problems determined that the fuel pump relay was bad. This pump would not spin up on key on. It is supposed to run 5 seconds and then turns off until you start the motor. It is labor day week end the Florida keys but we found a couple of used relays. But neither of the worked perfectly. They would be intermittent or work and the die. What is happening is the the relay is getting old and building up resistance. I think this in turn drops the voltage to the fuel pump causing a greater current draw and slowing the fuel pump. Goes on until relay overheats and cuts power to both the fuel pump and the injectors. Dead. Got a mechanic to make a new one using the wires from one of the old non working relays. He used a seimens relay from a mercury. About the same size and fits in the space. Seems to be running well now. Hope this helps.