Yamaha Y2000 150 HPDI runs rough after drifting boat

[Bobmcc1000]

We have a new-to-us 2000 GW adventure with a 2000 150 HPDI 2 stroke Z150XTR. The engine is acting strangely. I have posted this issue in "The Hull Truth" as well. Hope it's OK to post both places.

If we go out and leave the engine running the entire trip we have no issues. However, when we go out fishing the engine seems to work well until we shut the engine down and drift the boat for a while. When we restart the engine after having it off for about a half hour it runs rough when increasing the throttle and refuses to go over 3500 RPM or so. This has happened twice.

The first time this happened we limped back in. We changed out the Racor and the plugs, four looked like normal two-stroke plugs, and two had a lot of carbon; they were the upper starboard side plugs. We took the boat out and ran it around the harbor, up to about 5100 RPM and it seemed to be happy.

Next trip out the same thing happened. The motor ran well until we drifted while eating lunch and fishing. Upon restarting the engine it ran rough and refused to run at high RPM. I shut the engine down and restarted it, and on the 3rd or 4th restart it ran normally again for the remainder of our trip, which was a mix of cruising and no-wake zones. We haven't been out again yet.

The previous owner told me he had the same symptoms, including the engine behaving well after a few restarts. They changed the plugs and thermostat and the screen filter in the clear tank in the engine (not the VST), and had not seen the issue since then. The engine was decarbed shortly before we bought it, and the oil linkage rod was adjusted - the tech said it was running too much oil. There were no malfunction codes in the ECU. The plugs were replaced then.

A major tune-up was done April 2012, and the filters, including VST, were replaced then. The hours weren't recorded, but it was at least 150 operating hours ago. At least 50 last year and about 100 this year. We figured we'd change the filters at season's end. (coming soon, since we're in MA)

If it matters, it was pretty rough when we were drifting; the boat was rolling a bunch.

We're using Yamalube 2M and Ring free, with stabil marine as well. Previous owner did not use ring free.

Any idea what the culprit is, and why restarting the engine a few times would cause the rough running to correct? Things to try? Things to avoid?

Thanks,
Bob

 

[cpt woody]

Re: Yamaha Y2000 150 HPDI runs rough after drifting boat

I'm not a mechanic but have a 200 hp hpdi and have had a lot of experience. 95 percent of the problems I've had are fuel constriction related. I asume a fuel restriction until proven otherwise. In my experience what you are describing, intermittent motor running roughness is a fuel contriction(s) issue. At idle, when my hpdi runs rough, it's either the water separator filter or the mid pressure canester filter. When I've turned the key on and off and then motor runs ok, almost always a partially clogged canester filter.good luck

 

[Bobmcc1000]

Re: Yamaha Y2000 150 HPDI runs rough after drifting boat

Thanks

I ended up replacing the vst filter, medium pressure cartridge filter, and lift pumps while I was in there. Not too bad a job. The vst filter screen was discolored but looked like it had plenty of clear area. The mp cartridge filter was fairly hard to blow through so I'm hoping replacing it will do the trick. Seasons over here :grumpy: and the motor is winterized, so we will have to wait till springtime to see if the problem is fixed.

Bob