2007 225 VMAX HPDI Troubles....

[tyfoford]

New Yamaha owner here. I purchased this engine on a new to me boat about a month ago. The engine has around 290 hours on it and was rebuilt last spring (no compression on cylinder 5) when the engine had 260 hours. At the time of the rebuild, the shop replaced all filters and performed a normal 100 hour service, including fuel bulb and spark plugs on top of a new power head. I test drove the boat and the engine exhibited no issues. I drug it home and ran the boat on the same tank of gas a few times with no noticeable issues. I filled the tank (50 gallon capacity) with 20 gallons of 91 gas to fill the tank completely. All previous owners and myself have added ring free and marine stabil. Since then, the engine idles rough and stalls often. Once it stalls, it is near impossible to get it running again without letting it sit first. When I attempt to start it, it sputters like it wants to fire, but it just won't go. If I can get the boat started, in gear, and apply a touch of throttle, it runs at all RPMS without any hesitation or loss of power. In fact, it runs better than any engine I have ever owned. I ran it nearly three consistent hours this last weekend trying to get the gas out of it to add new. I suspected it was bad gas, so I figured if I emptied it and added new, the problem would likely go away. I have added nearly 40 gallons of gas since then with no change. I finally called and scheduled a service last weekend, but they can't get me in until the 30th, which was expected. I ordered all new filters and plugs yesterday in hopes I could change them all this weekend and possibly resolve the issue before I take it to a shop and spend mega money. Can anyone recommend any other things to check other than filters and plugs? The bulb remains hard and it seems odd to me these filters would already be causing issues after only 30 hours of use. I plan on also trying to completely drain my gas tank this weekend (headache....) to start over to eliminate that potential problem, too. PLEASE HELP! I want to like the Yamaha, but so far, first impressions aren't good.

Thanks

[mrdeath]

Bad low pressure fuel pumps will cause those symptoms. There are 2 of them on the port side of the engine. Pretty easy to replace and surprisingly inexpensive as far as Yamaha parts go. I think they're around $40 a piece.

[rid 05 198]

Not sure. Update when you can on what you found.

[tyfoford]

I replaced low pressure fuel pumps today with no change. Afterwards, I got all excited when I found my spark plugs were fouled. I changed them out, but no success... compression test showed good pressure readings. New filters and fuel bulb aren’t here yet, so I haven’t replaced those. I have now added spark as a suspicion. Possible stator trouble? At idle, I am getting low rpms both in and out of gear, but I suspect the tps is set correctly (was set last March at the time of the rebuild) and the idle issue is causing lower, inconsistent rpms. Still willing to hear any recommendations. Boat goes to the shop on the 30th. Fingers still crossed for a fix very soon.....

[reelmin5]

Install/replace a Yamaha 10 micron water/fuel separator filter before you go thru the trouble of replacing all those filters!

[tyfoford]

New fuel/water separator is on the way, too. Just haven’t received it yet. I think I may pull the old today just to see if I can find anything. Shipping is the only thing holding up my project at this point. I will report back once I find anything more so others with similar issues might get some ideas.

[Thamelau]

I would recommend checking your oil supply throttle linkage system. I think these motors usually fail safe, and dump too much oil. If your linkage broke, it could dump too much oil when starting and idling, but when you push on the accelerator a bit, the fuel/air/oil mixture gets closer to ideal, and she runs.

Just an idea of a potential repair that would be a cheap and relatively easy system to check out.

[tyfoford]

Ah. That actually could be the exact system I am having trouble with. I pulled the plugs this weekend and noticed they were very oily and "fouled", but when I would rev, it would blow everything out. This was even the case when I put new plugs in, ran for 5-10ish minutes at idle, killed the engine, then checked the new plugs. Found them "fouled" again, but not as bad. Is there a known part that typically goes bad in this system?

[tyfoford]

Note: I checked compression and everything checked out, so even though plugs were oily after idling, I don't suspect any powerhead or piston issues.

[rid 05 198]

Note: I checked compression and everything checked out, so even though plugs were oily after idling, I don't suspect any powerhead or piston issues.

my oil linkage end joint was broke, allowing movement.
IMG_20210420_130711691.jpg

[Thamelau]

I second rid's idea on the linkage. I have broken those things as well. Also, if it is just out of adjustment, it may allow over extension past 0 sending it into a safety mode. I do not know for sure, but what I am getting at is to check the linkage end and the adjustment.

[Charlie206]

What you describe sounds very much like a TPS or link and sync issue.

[Thamelau]

What you describe sounds very much like a TPS or link and sync issue.

This is another great idea.

[tyfoford]

All filters have arrived and I plan on replacing them this weekend. I also plan on checking TPS voltage and performing a link and sync procedure if the filters don't solve my issue. I ordered a Yamaha service manual, but it won't be here until next week. I have scoured the internet for a procedure to follow but the process in the link below is the only thing I can find that sort of explains the process. Can anyone confirm this process is accurate? If not, does anyone have any leads to better information on how to perform the procedure? Any leads would be super helpful and appreciated. I would love to get everything completed this weekend so I can start enjoying my new boat ASAP and so I can potentially save some money by not having to take it to the dealership. I am pretty capable of small to medium sized mechanical projects, so I would love to do this myself.

Thanks to everyone so far for the replies!

http://www.bbcboards.net/showthread.php?t=778399

[SCOTT196]

Take it to Hydrotec in Nixa if you cant fix it yourself .

[Thamelau]

It sounds like you are a pretty handy guy that would benefit from having YDS 1.33 software. You can find it for like $30 on eBay and the one I purchased included a ton of Yamaha Manuals.

[tyfoford]

Boat and motor finally went to the shop last week. They ran diagnostics and everything checked out squeaky clean. While running in the shop, they noticed my idle issue, but they expect it to be worse (it is) on the lake and expect to have to trouble shoot with the computer under normal use. They plan to lake test it next week and have already been on the phone with Yamaha, so fingers crossed. I would love to have my boat in working order within the next few weeks. I already missed the crappie spawn, so the rest of my summer fishing is at jeopardy now.

[tyfoford]

For anyone still following, my boat is still in the shop, but they are making progress. During a lake test last week, they ran the engine with a timing light and the computer hooked up. No codes were present and the timing appeared to be normal. The area Yamaha rep actually came to the shop unexpectedly last week and they recommended low pressure fuel pumps or an injector cleaning. I already replaced the pumps, so the injectors are headed to Hydrotec tomorrow for service.

While I hope this solves my problem, I do find it odd my injectors could already be fouled. When the motor was rebuilt last March, 30 hours ago, the injectors were supposedly cleaned and service as well as the VST, etc. Is it likely the system could have been fouled in only a year/30 hours of use? I figured in 30 hours, the fuel was cycled enough that I wouldn't be seeing any ethanol or stale gas problems.

[tyfoford]

New updates. Shop called last week right as they were preparing to ship my injectors off for cleaning and said they thought they found the problem. When I replaced the low pressure fuel pumps, I apparently didn't put a gasket behind the lower pump which was creating a slight air leak. ROOKIE MISTAKE. The shop installed the gasket and reset the tps voltage. I was able to pick the boat up and they said I should be good to go. My boat is running better as of this weekend, however, the idle is a touch high at 900 rpms out of gear and still varies about 50 rpm up and down (idle speed from 850-950) just like before. I suspect if I have the tps voltage adjusted again to get it down to the normal 750ish rpm, I will see the same issues. Can I continue to run with a slightly higher idle or is it too hard on my lower gears to shift in and out with an idle speed that high? I plan on shipping the injectors and doing a full filter clean at this point just to cover everything maintenance related. I am feeling more motivated to do the full service myself now than I was a month ago.