HPDI Fouling Plugs

[Twin R]

I have twin 2001 150hp HPDI that have been fouling plugs at low rpm from *****ing for long periods of time. Any recommendations on how to resolve? Engines have roughly 200 hours on them. The plugs only had 20-hours of runtime on them.

Also, when one of the engines is fully tilted, oil leaks out of the cap/sensor combination. Will a tied wrap resolve this issue?

[Hamfisted]

Buy yourself a service manual from www.YamahaPubs.com. Check the oil pump linkage adjustment (should be against the stop at idle...). If that doesn't solve it there have been issues of the oil pump leaking oil into the crankcase and causing plug fouling on the HPDI motors. You may need to clean your O2 sensor as well.


Mike

[Twin R]

Thanks Mike,

I've got a service manual ordered and will dig into the other items this weekend.

Have any thoughts about the Ring Free additive?

Thanks again for the feedback.

[jb123]

worth every penny.

[Hamfisted]

Personally I use Sea Foam (Advance Auto stores...) rather than Ring Free. It's stronger and cheaper, when I use to run Ring Free I still had plug fouling problems in the HPDI. Switched to Sea Foam and the motor seems to run cleaner and no plug problems at all.


Mike

[Ken]

Mike,
What's your routine on using Sea Foam? All the time? 1 oz per gallon? Shock treatment once a year?
Ken K

[Hamfisted]

Ken I use Sea Foam all the time. I run it in the gas tank with every refueling, trying to use 1oz per gallon or so. I use Amsoil HP and the HPDI motors don't seem to burn as much oil anyway. I don't get any smoke, anytime. 750 hours.


Mike

[Twin R]

Mike, You were right on, about the adjustment on the oil linkage. It was about a 1/4 open on one engine and a 1/3 on the other. After making the adjustments, it seems that the motors run smoother at lower rpm. Why was this adjusted like this? Is this the break-in period for the engine and is readjusted after runtime? Curious of why?

Also, thanks for the feedback on the Ring Free. Always looking to save some monies if another product is as good or better than what the manufacture recommends.

I also have some more never ending questions.

1. The water sensor is flashing on the fuel totalizer gauge. Over the weekend, I cleaned the fuel water separators on each engine and it seemed to stop, then it came back on Monday. Glancing through my service manuals I got yesterday, it looks as if sensor is defective and I need to replace the whole fuel cup. Would this be correct?

2. You mentioned earlier about checking the O2 sensor. Should I still pursue and check this? Or just change it to make sure it is operating without any defects?

3. I notice you can buy software and hookup a laptop to the motor and do some diagnostic checking. Is this of value? Plus since I have twin engines, I could see the benefit of help identifying certain things like which water sensor has failed, which the flashing sensor on the fuel management doesn't differentiate the motors. Plus check items like the O2 sensor.

Thanks again for your help.