2009 Yamaha HPDI 150 2 Stroke Stalls at Almost WOT

[ljlkrl05]

I bought a 2009 Yamaha 150 HPDI 2 stroke from the original owner and put it on a used Stratos bass boat I bought from the original owner, but different person than the motor.
I put a Yamaha control box and hotfoot with new throttle and shift cables on the boat.
The motor runs strong and smooth up until I get the hotfoot to a certain position, almost to the wide open position, then the motor loses power.
If I let off the hotfoot just a little, the motor picks back up and runs fine again. If I never press the hotfoot to that certain position, the motor never misses a beat.
I get about 60 to 62 mph at 5200 to 5300 rpms before the problem occurs. I am not looking for more speed, but I am concerned about damaging the motor.

This is what I have done so far to eliminate the problem, with no success:
Changed spark plugs
Changed VST filter
Changed Strainer above VST tank
Cleaned the filter behind the VST tank
Changed fuel filter in under cowling water separator
Changed basket filters on high pressure fuel pump
Changed basket filters on injectors
Sync & Link and adjust TPS according to Yamaha service manual
Checked resistance of spark plug caps. One is about 5.8 but still in spec, all others near middle of 4 to 6 k ohms.
Remove fuel tank from boat and clean it
Verified vent line is clear
Remove anti siphon valve from pickup tube
Remove screen from bottom of pickup tube
Cut bottom of pickup tube at a slight angle on bottom
Replace fuel line from tank to motor
Replace primer bulb with Yamaha brand bulb
Replaced 10 micron water seperator assembly and filter in bilge
Replaced the shift position indicator switch under the cowling. It had a crack in a wire near the switch.
Purchased YDS and cable and monitored fuel pressure at the high pressure pump. It stayed right at 700 psi and did not drop when the problem occurred.
There are no trouble codes in the computer.

I am about to remove the injectors and send them off for cleaning and testing.

I am considering adjusting the stop bolt on the hotfoot so it will not travel far enough to hit the problem spot, but it is driving me nuts knowing the motor should not be doing this.

I have seen many posts on different forums with similar problems, but none of them match this one exactly, at least not that I can find.

I welcome any suggestions you may have.

[99yam40]

Sounds like you covered the stuff I was thinking of.

might explain better what you mean by the motor loses power.
Do RPMs drop a little, a lot, how far, or shut down completely?
Does the sound of the motor change?
any vibration?
Do gauges show anything strange?

And post a complete motor model # just to be sure everyone knows exactly what motor you have

[ljlkrl05]

Sounds like you covered the stuff I was thinking of.

might explain better what you mean by the motor loses power.
Do RPMs drop a little, a lot, how far, or shut down completely?
Does the sound of the motor change?
any vibration?
Do gauges show anything strange?

And post a complete motor model # just to be sure everyone knows exactly what motor you have

Motor is a VZ150TLR
RPMs drop, I do not know how far because it scares me to just hold it there to see.
I have not heard the sound of the motor change, but will try to pay closer attention next time I run it.
It feels to me like it loses fire but the YDS says all plugs are firing at the time.
Gauges do not do anything funny.
I was thinking it might be the TPS but am not certain what to look for when I test it with a volt meter. I put my son in the seat working the throttle in the driveway with the motor off and laptop connected. I was watching the TPS voltage on a meter and the laptop. I told him to move the throttle slowly to where he thinks it starts acting up, since he drives it more than me.
The TPS voltage was at about 3.8 when he got to where he thinks it acts up.
I will have to run it and watch the laptop while he is driving to verify this though.

Someone else told me to check the flywheel, said it could be loosening up at high rpms, but I don't know about that.

[99yam40]

Hopefully rod will see your thread and post soon

[rodbolt17]

remember
yds will record the last 13 min or so of run time.
so hook it up,run it till it fails.
hit the save button.
I had a VZ250 some years back that would run 13 min exactly above 5200 before it failed.
turned out to be over voltage from the pulser coil.
don't ask how long that took to find.

[ljlkrl05]

remember
yds will record the last 13 min or so of run time.
so hook it up,run it till it fails.
hit the save button.
I had a VZ250 some years back that would run 13 min exactly above 5200 before it failed.
turned out to be over voltage from the pulser coil.
don't ask how long that took to find.

I plan to go run it this weekend with the laptop.
Could the injectors cause something like this?

[ljlkrl05]

While removing the injectors to send them off for cleaning and testing, I found this wire to my #1 injector damaged. I wonder if this could be the problem?

[99yam40]

It is a problem that needs to be fixed, if it shorts to ground I think it might cause some major problems when it looses a cylinder

[ljlkrl05]

It is a problem that needs to be fixed, if it shorts to ground I think it might cause some major problems when it looses a cylinder

I fixed it. Wondering if it was causing any issues.

[matteogiannix]

solution?

I fixed it. Wondering if it was causing any issues.

Hi did you finally find out what the roblem was. I am experiencing a similar problem with my 150 hpdi outboard

[pstephens46]

Start a new thread. That guy is long gone.

Give exact model number

And it sucks he never came back and reported his outcome.

[ljlkrl05]

Start a new thread. That guy is long gone.

Give exact model number

And it sucks he never came back and reported his outcome.

I tell you what, I read so many reports of the same or similar issue I was having with no outcomes it was frustrating.

My issue finally resolved itself when the top right piston came apart and knocked a hole in the cylinder wall into the one below.

I don't know what caused it, but I guess it was running lean and got too hot.
I spent so much time and money trying to figure it out and nobody I took it to saw a problem.
I sent my injectors to Brocato and they cleaned and adjusted them so I cannot say for sure if it was an injector problem or what.

All I can tell you is find the best Yamaha mechanic you can and let them go through it with a fine tooth comb.

I have since bought a new Mercury Pro xs 150 with a 6 year warranty.

[ljlkrl05]

Hi did you finally find out what the roblem was. I am experiencing a similar problem with my 150 hpdi outboard

If you are interested I have a Yamaha service manual and the diagnostic software and cable for this motor I will sell you.
I replied to your question a minute ago.

[matteogiannix]

I tell you what, I read so many reports of the same or similar issue I was having with no outcomes it was frustrating.

My issue finally resolved itself when the top right piston came apart and knocked a hole in the cylinder wall into the one below.

I don't know what caused it, but I guess it was running lean and got too hot.
I spent so much time and money trying to figure it out and nobody I took it to saw a problem.
I sent my injectors to Brocato and they cleaned and adjusted them so I cannot say for sure if it was an injector problem or what.

All I can tell you is find the best Yamaha mechanic you can and let them go through it with a fine tooth comb.

I have since bought a new Mercury Pro xs 150 with a 6 year warranty.

Thank you very much.
Just one question, as I am not sure I got everything right (for language reasons, I am in Italy). Before having the piston/cylinder problem, you sent your injectors for cleaning/adjusting and had the problem fixed, is that correct? So we can say that in your case it was an issue with the injectors?

[ljlkrl05]

Thank you very much.
Just one question, as I am not sure I got everything right (for language reasons, I am in Italy). Before having the piston/cylinder problem, you sent your injectors for cleaning/adjusting and had the problem fixed, is that correct? So we can say that in your case it was an issue with the injectors?

I cannot say it was the injectors.
I sent them in to have them cleaned as part of the troubleshooting.
When they came back and I installed them, the motor seemed to run smoother, but I still had the same problem of losing power at top end.