Yamaha 150 VMAX Just Died

[99yam40]

Well, I am no long able to tap on the VST Tank to enable the VST fuel pump to run, so I can start the motor, and see if we are maintaining 12+ volts when the problem occurs.

not sure how the motor will start and run if you cannot get the pump to run.
if the pump will not run. see what it is missing + or the ground

[Captain Steve]

Pump

Yesterday, when running the above tests that Rodbolt suggested, I was able to tap on the VST with the palm of my hand, it would run for 3-5 seconds, and I could then start the motor. But if I idled up on the throttle, it would die. Today, I am no longer able to get the pump to run by tapping on the VST. Therefore, unable to determine if I have voltage at the red wire when the motor dies at idle up.

What I have just checked and confirmed, when I turn the key on, there is no power at the blue wire (same as yesterday).

Can you tell me where the blue wire goes, or where I might should be looking for a lose ground or a short? Should I start removing the VST? Rodbolt mentioned a "Relay", where can I find this relay?

Thank you.

[99yam40]

check the red wire to see if it still has 12V+.
the relay should be what gives it this voltage.

Use the meter to check for voltage.

if you do not read any voltage on the blue wire then either there is no pos voltage to the pump red wire, the brushes are not making contact and letting it show up on the blue wire, or the blue is grounded as it should be to make the pump run and will not show a voltage difference.
But should not stay grounded except for the 1st few seconds of key on.

[scofflaw]

Grab that spare motor from your buddy

[Captain Steve]

Voltage & Spare Motor

Red wire has continuous voltage supplied to the VST.

I will go pick up spare motor Wednesday or Thursday. I would just like to confirm that the pump is actually the problem, if that is possible.

I appreciate all the help.

[99yam40]

If you jumper a ground to the blue wire connector at the motor and it does not run when 12V+ is on the red wire to the pump then I would say the pump is bad.
as a matter of fact you can jumper the + and neg to the pump to see if it will run, by passing everything else

[Captain Steve]

Jumped Voltage to the pump

Ok, as suggested, I have jumped 12 volts directly to the pump, and nothing happens. Absolutely nothing. Nada!

I jumped blue to ground and red to +.

So hopefully you guys have diagnosed the problem, and I can get it fixed and back on the water by Wed/Thur.

I will update you all when I go pick up the pump from my buddy.

Thanks all!

[pstephens46]

Wonder what the outcome was here?

[Captain Steve]

Outcome

My apologies for not updating all with the outcome.

Wednesday of last week I went and pulled the fuel pump from the VST Tank of my buddies blown motor and stuck it in my motor. Fired up on first crank and I have been running the boat with it every day since, and she is performing great!

Thanks for everyone who has helped! You guys are awesome and I very much appreciate it.

Cheers,

Captain Steve