HPDI 200 - how smooth should it run at low RPM?

SoLucky

GreatGrady Captain
Joined
Dec 8, 2020
Messages
44
Reaction score
21
Points
8
Age
56
Model
Seafarer
Definitely check the O2 sensor and O2 Sensor Draw Tube. I have found that this is the culprit of my idle issues and cold start issues when the carbon has built up and starts to clog the air flow.
I have tried everything to reduce the carbon, but now down to each season, do a Seafoam decarb, pull the O2 sensor and clean out all the carbon, soak the parts overnight, except the O2 sensor itself, must be careful not to damage it. When put back together, starts perfectly and idles right at 700rpm like it should.

Thanks, ROBERTH and everyone else for sharing your knowledge with me. Collectively y'all have already made a world of difference in how it runs. Setting the TPS right helped a lot. I think it was running very rich at lower throttle openings (since the TPS was out of calibration) and that was causing the engine to stumble. Once the O2 sensor is clean and working properly I expect the small remaining stumble/roughness will go away. I'll pull the O2 sensor, housing, and spindle in the "draw tube" this Sunday and clean it all up. And, if I have the time, I'll splash the boat and test out the results.
 

ROBERTH

GreatGrady Captain
Joined
Jun 10, 2006
Messages
1,123
Reaction score
53
Points
48
Location
Raleigh, NC
Model
Sailfish
I use Ring Free religiously and still have lots of carbon. The O2 sensor itself is always clean. It is the chamber that is clogging up not allowing the sniffing to work properly for the O2 sensor to get an accurate sniff and make the adjustments. That is my theory so far.
I just don't get the carbon buildup. I run my engines hard, but I do troll a lot. I run nearly 2 hours out and back and always go as fast as the seas allow. Was running 38mph this past weekend back from 30 miles. That is about 4600 to 4800 rpms. I usually give it a 1 mile blast on the way back to the dock.
Even then I still get carbon buildup that requires the decarb and cleaning of the chambers.
 

seasick

Well-Known Member
Joined
Aug 19, 2008
Messages
6,297
Reaction score
616
Points
113
Location
NYC
I use Ring Free religiously and still have lots of carbon. The O2 sensor itself is always clean. It is the chamber that is clogging up not allowing the sniffing to work properly for the O2 sensor to get an accurate sniff and make the adjustments. That is my theory so far.
I just don't get the carbon buildup. I run my engines hard, but I do troll a lot. I run nearly 2 hours out and back and always go as fast as the seas allow. Was running 38mph this past weekend back from 30 miles. That is about 4600 to 4800 rpms. I usually give it a 1 mile blast on the way back to the dock.
Even then I still get carbon buildup that requires the decarb and cleaning of the chambers.
Have you checked the oil pump linkage adjustment? Excess oil will also cause carbon buildup. Also check that you are running the correct spark plugs.( how do they look?)
Also research the issue with that spool that connects the chamber to the O2 sensor. Some years ago, a new version was made for SX motors. The shape of that part was changed. I am nor certain if it applies to your motor
 

SoLucky

GreatGrady Captain
Joined
Dec 8, 2020
Messages
44
Reaction score
21
Points
8
Age
56
Model
Seafarer
I'm a little tardy with an update. I cleaned the O2 sensor, chamber, and the "spindle" tube (I don't know its official name). I ran the boat this past Saturday and low RPM running is somewhat improved, but still a bit rougher then I would like. I have now replaced the O2 sensor with the $30 equivalent from NTK. Splicing on the Yamaha connectors took about 10 minutes and saved $300. I haven't run it yet, but will be heading out striper trolling on Friday, which will be a good test.

Next up will be what Seasick suggests -- checking the oil pump linkage. I think mine is over oiling, as the plugs were quite damp with oil when I changed them a few weeks back and their color wasn't right. Those plugs may have been the wrong temp. New ones are from SIM Yamaha. They sent NGK BKR-6ES11-00-00 -- are those the correct hotter plugs?

Things are trending in the right direction and with a few more tweaks she should be purring properly.
 

ROBERTH

GreatGrady Captain
Joined
Jun 10, 2006
Messages
1,123
Reaction score
53
Points
48
Location
Raleigh, NC
Model
Sailfish
Hi Seasick, I have adjusted the oil linkages. They were off and I am saving a lot of oil last year. So I know that is not it now. The plugs burn pretty clean, never oily. They are the recommended plugs, same as what came in it. NGK BKR7EKU. I installed the new OXYGEN SENSOR DRAW TUBES 68F-11353-00-00 because the originals looked a bit worn and not seating properly. When I serviced the O2 sensor this season, the draw tubes looked perfect, just some carbon on them but it came off easily. I have definitely improved the carbon, but nonetheless, still have the buildup. Same in both motors. I know many others with these same engines are having the same issue.
 

DennisG01

GreatGrady Captain
Joined
Sep 1, 2013
Messages
4,508
Reaction score
495
Points
83
Location
Allentown, PA & Friendship, ME
Model
Offshore
I use Ring Free religiously and still have lots of carbon. The O2 sensor itself is always clean. It is the chamber that is clogging up not allowing the sniffing to work properly for the O2 sensor to get an accurate sniff and make the adjustments. That is my theory so far.
I just don't get the carbon buildup. I run my engines hard, but I do troll a lot. I run nearly 2 hours out and back and always go as fast as the seas allow. Was running 38mph this past weekend back from 30 miles. That is about 4600 to 4800 rpms. I usually give it a 1 mile blast on the way back to the dock.
Even then I still get carbon buildup that requires the decarb and cleaning of the chambers.
Hmmm. I wonder the difference is, then. I also use Startron (and usually more than recommended). But the last time I pulled my O2 sensor and draw tube out, they were clean. I even took the draw tube with me to the Yamaha dealer when I picked up a new gasket and the service manager took one look at the tube and said "You must be using RingFree" :)

If I get the chance, I'll pull it out again and check as it's been a couple years, now.
 

ROBERTH

GreatGrady Captain
Joined
Jun 10, 2006
Messages
1,123
Reaction score
53
Points
48
Location
Raleigh, NC
Model
Sailfish
Yeah, I am in the same mode of thinking. Seems some engines have this issue and others don't. I have 2 and they both do the exact same thing.

I use Startron and Ring Free Plus together. I started switching over to the new Marine Techron to see if it helps. Hard to say right now

The only thing I can think of is the oil. I was using the Pennzoil Semi Synthetic for a few years. Switched over to Amsoil and using it now. It does a bit better with the Amsoil which is a full synthetic. I was reading an article a while back about the Yamalube 2 stroke oil has a lower ash content to control the excessive carbon. Was thinking to swith over to that for while once I burn through my Amsoil. I found it interesting the Amsoil, which I love says absolutely nothing about the ash content. So maybe this could be something......dunno..

What oil are you using?
 

georgemjr

Well-Known Member
Joined
Jan 2, 2009
Messages
399
Reaction score
13
Points
18
Location
Bay Shore, Long Island NY
2X the oil. I was a religious Yamaha fanatic, ring free/yamalube, but I switched over to a synthetic oil as I found the yamalube created too much buildup and the synthetic burned cleaner.
 

ROBERTH

GreatGrady Captain
Joined
Jun 10, 2006
Messages
1,123
Reaction score
53
Points
48
Location
Raleigh, NC
Model
Sailfish
Ouch Dennis! That is way more than even the Amsoil....lol. I go through 2 gallons each offshore trip. Amsoil compared with the XD100, but again, the additives would be different I am sure.

Would be great to find out if anyone has used the 2M oil and does not have carbon buildup.

Here is what I was referencing about the Yamaha 2M oil regarding the claim of less carbon buildup. Somewhere else I found some discussion about the lower ash content.


Without a doubt, Yamalube 2M is the oil to use in Yamaha HPDI engines. While it’s possible to use other brands of two stroke oil without voiding the warranty, Yamalube 2M oil is the clear choice of boat owners who want the most out of their engines. There are several subtle differences between Yamalube 2M oil and the oil of other leading competitors. One central difference is the additives in Yamalube 2M that reduce the buildup of carbon in the engine. In addition, there are other additives to reduce condensation in the gas tank, and ensure the engine continues to operate at peak performance. It’s possible to save some money purchasing a cheaper two stroke oil, but the money saved on purchasing an inferior brand of oil is far insignificant to the cost of boat ownership. Yamalube 2M oil preserves the condition of the engine, and overall the engine will require less maintenance over its lifetime.
 

ROBERTH

GreatGrady Captain
Joined
Jun 10, 2006
Messages
1,123
Reaction score
53
Points
48
Location
Raleigh, NC
Model
Sailfish

SoLucky

GreatGrady Captain
Joined
Dec 8, 2020
Messages
44
Reaction score
21
Points
8
Age
56
Model
Seafarer
Replacing the O2 sensor and adjusting the oil pump linkage seems to have done the trick. The oil pump linkage was set 1/4" too long and causing over oiling at idle / low revs. The engine is running very nicely now with a smooth idle and no surging as I slowly throttle up and no blue smoke at idle, either.

My next project is replacing the oil tank strainer/filter. Parts ordered, will tackle that in a few weeks when I have the time.
 

seasick

Well-Known Member
Joined
Aug 19, 2008
Messages
6,297
Reaction score
616
Points
113
Location
NYC
Replacing the O2 sensor and adjusting the oil pump linkage seems to have done the trick. The oil pump linkage was set 1/4" too long and causing over oiling at idle / low revs. The engine is running very nicely now with a smooth idle and no surging as I slowly throttle up and no blue smoke at idle, either.

My next project is replacing the oil tank strainer/filter. Parts ordered, will tackle that in a few weeks when I have the time.
I am curious about your offshore trips. When you used up 2 gallons of oil, how much gas did you burn? Also, is this boat a single motor?
Thanks
 

ROBERTH

GreatGrady Captain
Joined
Jun 10, 2006
Messages
1,123
Reaction score
53
Points
48
Location
Raleigh, NC
Model
Sailfish
Seasick, in my case when I use 1 gal per engine on a long offshore trip trolling for hours on end, I burn about 100-110 gallons usually. Those are hard running as fast as I can stand and usually with bow down pushing the waves down with a bit of bow steer in some cases. These NC seas are always a challenge when I seem to get a chance to go. On calmer days, I don't burn as much fuel and oil.
 

seasick

Well-Known Member
Joined
Aug 19, 2008
Messages
6,297
Reaction score
616
Points
113
Location
NYC
That works out to about 50 to 55 gals per motor and 1 gal oil per motor or a ratio of about 50-55 to 1. For a lot of low speed trolling, I would expect that ratio would be closer to 100 to 1. It's not an exact science since I don't know the percentage of cruising speed versus trolling. It does seem that the oil adjustment was too high a a rate though. It will be interesting to see if any by how much the oil consumption declines now that the oil linkage has been calibrated.
 

ROBERTH

GreatGrady Captain
Joined
Jun 10, 2006
Messages
1,123
Reaction score
53
Points
48
Location
Raleigh, NC
Model
Sailfish
Actually, I did the oil adjustments before last years season. Even after mechanics have checked a couple of different times, both times they said it was correct, but when I checked, it was not ok per the manual so I made the adjustments.
Before, I would use more than 1 gallon per motor on this same amount of fuel and type of trip. Maybe 1.2 gallons would be pretty close. Now, I am just under a gallon so significant less oil consumption. Yet, still the carbon buildup, but I don't think it is as bad.
 

naesb81

Active Member
Joined
Jan 14, 2020
Messages
33
Reaction score
8
Points
8
Location
Boston
Model
Express 265
I took the boat out today and it runs better now with the TPS voltage calibrated and the butterflies synchronized. Still kind of a loping idle, but smoother than it was and no hunting/surging. Next up will be the O2 sensor and housing -- I'll clean those up good and may swap to the new sensor I bought if the current one is too dirty. My last two Yamahas have been four strokes, so I'm used to a quietly purring engine and a smooth idle... so maybe I just need to get used to the 2-stroke idle?

I also tried to start in both forward and reverse and it wouldn't crank, so the neutral switch is good. Overall it runs very well. 4 people on board, ice & drinks, with light chop and running into a 14 mph wind we topped out at 38 mph at 5100 rpm with engine trimmed up most of the way. Running back with the wind and waves we hit 41-42.

How rough is rough? you can certainly tell that the HPDIs are on 4 in idle, once kicked into gear it should sound different and smooth out. Run it next to an ox66 and determine if you still think it is rough :). If you are topping out at 5100, you are likely running on all 6. If you have not changed your VST in a while, that may be preventing full top end.

That being said, here is my write-up of issues and solutions with my HPDIs not making max rpm. you have an idle "issue" so it may not be the same but it is worth knowing how the HPDIs work. There are lots of things that could contribute to that. Great motors that love good fuel and good voltage. Mine fouled a lot of plugs with Yamaha Lube.


there is a neutral switch in the binnacle which prevents the motor from starting in gear and a shift position switch in the motor. There is a slide on a track that closes that switch when the motor is in neutral.

It's part #47 on the diagram. I will be on the starboard side of the motor. Check the continuity of the switch. Manually operate it ON while you have the meter on it. Put it in neutral, check the continuity of the switch. Shift to forward, check the continuity again. It should be closed (ON) when the boat is in neutral, open (off) when shifted into gear.

The shift position switch needs to be ON when the boat is started. if it is in the OFF (open) position when the motor is started, it will only ever run on 4 cylinders (2 and 3 are off) until it is restarted with the switch in the correct position. You should confirm if it is running on 4 or 6. put it in gear (it runs on 4 in neutral) and pull the plug cables one by one (start on #2 and #3 as those are the ones that would be off) if they drop you are running on 6. If no change you are on 4. if it is running on 6 you have ruled out that switch. If you confirm you are on running on 4, hold down the switch and have someone start the boat. Let go of the switch, if it kicks to 6, your switch is not correctly engaged when in neutral. You may be able to adjust the slide or switch to correct the engagement. If you are still on 4 it could be a bad switch (stick in the closed position). Jump the connection, start the boat, pull the jumper, you should hear it kick into 6 cylinders. if it does replace the switch (topping at 2500 happened to me when the motor was running on 4)

if you are running on 6, I would check fuel delivery. Your mid pump on the vst should always read 50 psi. You need to watch it as you get up to your top RPM. If it drops below 50psi, your hose, filter, VST Filter (this get clogged quickly with ethonal fuel), LP fuel pump or mid fuel pump are the likely issue. If it holds, the next check is your inline medium pressure filter then the HP fuel pump. The VDS can log this for you. It should read somewhere around 700psi. if it falls off at your top RPM, that is your likely issue. I had both of mine HP pumps rebuilt by injectorRX, solved my pressure issue.

I still had an issue topping out at 4400 RPM, turns out I had a stuck open injector. Replaced that and I was back in business.

One thing to note is HPDI like good power. If your battery is bad or the stator is not producing enough juice, it can screw everything up.

Hope this helps
 

SoLucky

GreatGrady Captain
Joined
Dec 8, 2020
Messages
44
Reaction score
21
Points
8
Age
56
Model
Seafarer
How rough is rough? you can certainly tell that the HPDIs are on 4 in idle, once kicked into gear it should sound different and smooth out. Run it next to an ox66 and determine if you still think it is rough :). If you are topping out at 5100, you are likely running on all 6. If you have not changed your VST in a while, that may be preventing full top end.

That being said, here is my write-up of issues and solutions with my HPDIs not making max rpm. you have an idle "issue" so it may not be the same but it is worth knowing how the HPDIs work. There are lots of things that could contribute to that. Great motors that love good fuel and good voltage. Mine fouled a lot of plugs with Yamaha Lube.


there is a neutral switch in the binnacle which prevents the motor from starting in gear and a shift position switch in the motor. There is a slide on a track that closes that switch when the motor is in neutral.

It's part #47 on the diagram. I will be on the starboard side of the motor. Check the continuity of the switch. Manually operate it ON while you have the meter on it. Put it in neutral, check the continuity of the switch. Shift to forward, check the continuity again. It should be closed (ON) when the boat is in neutral, open (off) when shifted into gear.

The shift position switch needs to be ON when the boat is started. if it is in the OFF (open) position when the motor is started, it will only ever run on 4 cylinders (2 and 3 are off) until it is restarted with the switch in the correct position. You should confirm if it is running on 4 or 6. put it in gear (it runs on 4 in neutral) and pull the plug cables one by one (start on #2 and #3 as those are the ones that would be off) if they drop you are running on 6. If no change you are on 4. if it is running on 6 you have ruled out that switch. If you confirm you are on running on 4, hold down the switch and have someone start the boat. Let go of the switch, if it kicks to 6, your switch is not correctly engaged when in neutral. You may be able to adjust the slide or switch to correct the engagement. If you are still on 4 it could be a bad switch (stick in the closed position). Jump the connection, start the boat, pull the jumper, you should hear it kick into 6 cylinders. if it does replace the switch (topping at 2500 happened to me when the motor was running on 4)

if you are running on 6, I would check fuel delivery. Your mid pump on the vst should always read 50 psi. You need to watch it as you get up to your top RPM. If it drops below 50psi, your hose, filter, VST Filter (this get clogged quickly with ethonal fuel), LP fuel pump or mid fuel pump are the likely issue. If it holds, the next check is your inline medium pressure filter then the HP fuel pump. The VDS can log this for you. It should read somewhere around 700psi. if it falls off at your top RPM, that is your likely issue. I had both of mine HP pumps rebuilt by injectorRX, solved my pressure issue.

I still had an issue topping out at 4400 RPM, turns out I had a stuck open injector. Replaced that and I was back in business.

One thing to note is HPDI like good power. If your battery is bad or the stator is not producing enough juice, it can screw everything up.

Hope this helps

Thanks... great info. Hopefully I won't experience problems with upper rev range power, but if I do you have provided an excellent tutorial on how to diagnose and correct. Much appreciated.

If you read through the rest of this thread you will see that my problem has been solved. The root cause was likely over oiling at idle as the oil linkage was well off from spec. A contributing factor could also have been my O2 sensor. I can't say for sure which was the bigger factor as I took care of both at the same time.

Many thanks to everyone who chimed in. Your knowledge and willingness to help out makes this site an incredible resource!