Yanmar Problems

[Charlie]

I have a similar engine the 4JH4E. On mine the lift pump is located on the injection pump. It runs with a cam from the engine and is a diaphram pump. If there is a leak in the diaphram your engine will get diesel fuel in the oil. It is hard to detect. A mechanic in Mexico had me change the oil run the engine for a half hour and then compare the viscosity between the half hour old disel and new lubricating oil. I ended up installing an electric fuel pump and bypassing the mechanical lift pump. When the oil level was too high I had a problem with the RPM's. My theory (unproven) was that the oil level was so high that it blocked a breather tube. Good luck resolving the problem.

[Dockhead]

Thanks for all the suggestions.

I am so far convinced that there is no problem in the fuel system from the tank to the Racors, because there is no vacuum and the filters are squeaky clean. The secondary filter was just replaced and had no effect on the problem.

Furthermore, the amount of fuel necessary to pull 3000 rpm with a load is probably what -- 10 times the amount of fuel needed to pull 3000 rpm with no load, right? So if the RPM is being limited by fuel, it would be impossible to see 3000 rpm with load but also see a cutoff of RPM with no load -- should rev freely up to redline, if the engine will make even 2000 rpm with load.

I really don't think it's a fuel problem. I have not checked fuel return and just didn't have time to do it before we had to do our crossing, but will do it as soon as I can just to be sure.

Meanwhile, the engineer in Jersey (a great guy; Tom and Fox Marine in case someone needs a Yanmar engineer in St. Helier) consulted with Yanmar technical support, and they suggested that it was likely to be -- of all things -- the stop solenoid. They said that these may have a partial failure which restricts fuel flow under certain conditions.

I don't believe it, but these are not expensive, so I think I will just change it to eliminate that question.

And if that doesn't work, and assuming I have successfully tested fuel return flow, then I think I will pop out the injection pump and have it tested. My hunch now is that it is a governor problem -- or something else in the injection pump.

I can't really think of anything else. In summary:

1. No exhaust restriction -- whistle-clean exhaust elbow and muffler
2. No air flow restriction
3. No turbo problem
4. No fuel problem at least as far as the Racors
5. Symtoms not consistent with fuel problem
6. No problem with compression -- judging by extremely easy starting as always
7. Anyway, runs perfectly, smooth and healthy, up to whatever RPM it starts cutting out at.

The only thing I can think of is injection pump or governor.

What do you guys think?

[Dockhead]

Originally Posted by Charlie

When the oil level was too high I had a problem with the RPM's. My theory (unproven) was that the oil level was so high that it blocked a breather tube. Good luck resolving the problem.

Interesting. The first time I had this problem, I had oil thrown around in the engine compartment from, I thought, my having overfilled the engine before departure. Yanmar dipsticks are very tricky to read. I reduced the oil level, and the engine ran perfectly for another year and a half.

I thought the oil was gumming up the turbo.

But that does not seem to be the problem here -- we washed the turbo (twice; once professionally) and ran the engine up with the breather and air filter off. So no way oil could have gotten into the turbo from the sump. Problem was there all the same.

I do not seem to be making oil (or burning it, either). Oil level is very consistent and sometimes I don't add any at all between 100 hour changes.

[chrisjs]

I assume you have already checked your prop for barnacles??
We keep our trawler in Fall River, MA and need to scrape the prop every 3-4 weeks in the season. It only takes a relatively small crop of barnacles to kill speed and create a major drag on the engine/transmission. Sometimes it hard to back out of our slip after 4 weeks of inactivity!!

[Dockhead]

Originally Posted by chrisjs

I assume you have already checked your prop for barnacles??
We keep our trawler in Fall River, MA and need to scrape the prop every 3-4 weeks in the season. It only takes a relatively small crop of barnacles to kill speed and create a major drag on the engine/transmission. Sometimes it hard to back out of our slip after 4 weeks of inactivity!!

We lifted out end of June and scrubbed, although bottom and prop were clean. Dived the prop recently in St Peter Port. Clean as a whistle.

But more importantly, the problem - not developing full revs - exists in neutral (see Post #1). So clearly not a result of a fouled prop.

[SailorHarry]

Have a good look for your fuel lift pump. My 4JH2E pump is under the fuel injection pump. You did not mention engine years or hours, but I rebuild my lift pump every 2200 hours to avoid failure. You can have an air leak between the fuel tank and the suction (inlet) to the lift pump and never see any diesel weeping out, so carefully check all fittings, and especially around the fuel selector valve (if you have more than one tank) or shut-off valve.

If you subscribe to Ocean Navigator mag, see my article on rebuilding lift pump, or I can email the text to you. Good luck. Harry Hungate

[Dockhead]

Originally Posted by SailorHarry

Have a good look for your fuel lift pump. My 4JH2E pump is under the fuel injection pump. You did not mention engine years or hours, but I rebuild my lift pump every 2200 hours to avoid failure. You can have an air leak between the fuel tank and the suction (inlet) to the lift pump and never see any diesel weeping out, so carefully check all fittings, and especially around the fuel selector valve (if you have more than one tank) or shut-off valve.

If you subscribe to Ocean Navigator mag, see my article on rebuilding lift pump, or I can email the text to you. Good luck. Harry Hungate

Thanks, I have PM'ed you with my email address. I would be very interested to read your article.

My engine is a 4JH3HTE built in 1999, presently with about 1300 hours. The lift pump is integral with the injection pump; it is a roller cell type, I think, without any diaphragm.

[Dockhead]

Update: Took the injection pump off and took it to a professional fuel injection machine shop, the one used by all of the marine engineers around here. Verdict: Pump is good as new without any faults of any kind.

Back to the drawing board.

[jeremiason]

When was the last time you checked the injectors?

I have the Yanmar 4JHE3 75 HP version and two of my sister ships had the same described problems. Turned out to be injectors.

[Charlie]

Hi Dockheard:

As said before I have a 4JH4E. I removed my injectors and have a pop tester. It has a maximum pressure of 3000 PSI. The range for the injectors is 3060 PSI and up. Three of my injectors are popping at around 2100 and the fourth I cannot get to pop at all. 2 of the four are dripping fuel. I have rebuilt injectors on my Mercedes (1987 300 td) but am not an expert. These Yanmar ones are hard to take apart because of a special fitting that requires a wrench that is not standard. I will take pictures of the injectors and post them here. I am thinking out loud -- but if the timing of the injection pump is off just a little would the advanced or retarded timing of the pump throw off the power under load. Also if the pressure of the injectors was off would this cause the same problem?

[Dockhead]

Originally Posted by jeremiason

When was the last time you checked the injectors?

I have the Yanmar 4JHE3 75 HP version and two of my sister ships had the same described problems. Turned out to be injectors.

Thanks for the suggestion. I replaced the injectors and nozzles entirely last year. Since the problem occurred once prior to this, and then flared up again this year -- after injector replacement -- it seems to me unlikely that this is the problem.

On the other hand, since I've already been through almost every obvious problem, perhaps it's not inconceivable that I have had two bad sets of injectors. Argggggh.

[Dockhead]

Originally Posted by Charlie

Hi Dockheard:

As said before I have a 4JH4E. I removed my injectors and have a pop tester. It has a maximum pressure of 3000 PSI. The range for the injectors is 3060 PSI and up. Three of my injectors are popping at around 2100 and the fourth I cannot get to pop at all. 2 of the four are dripping fuel. I have rebuilt injectors on my Mercedes (1987 300 td) but am not an expert. These Yanmar ones are hard to take apart because of a special fitting that requires a wrench that is not standard. I will take pictures of the injectors and post them here. I am thinking out loud -- but if the timing of the injection pump is off just a little would the advanced or retarded timing of the pump throw off the power under load. Also if the pressure of the injectors was off would this cause the same problem?

Hmm. Well, remember the problem is not power under load -- it's revs, and the problem exists also without any load at all. Other than the governor, I just can't figure out what could possibly cause this.

But injection timing? Maybe. I just don't know enough about diesels to say. In any case, the pump will be put back on tomorrow and I will have a real pro -- the Yanmar main dealer -- set the timing. Who knows?

[delmarrey]

Originally Posted by Dockhead

We are at anchor behind Isle Brehat, in North Brittany. Yesterday we bought the most delicious things at the weekly market in Tregieur, and I cooked them last night, freshly killed chicken with delicious Roscoff onions in olive oil, fresh green beans. Ah, life is sweet.

Except that I am troubled again by my main engine, a Yanmar 4JH3 HTE, 100 horsepower turbocharged and intercooled, next to last generation so purely mechanical fuel injection.

I have had this problem off and on for two years -- the engine will lose revs. It happened once in a storm at night in extremely rough conditions -- engine wouldn't rev past 2300 or so so I shut it down. When we got into port I discovered that the engine had puked oil all over the place, apparently through the breather. I came to the conclusion that the turbo was gummed up by the oil. The problem went away by itself.

Later from time to time the engine would fail to make max revs (3800 rpm), but would usually run up to 2800 or 3000, which is all I ever use anyway. I assumed that the turbo was acting up and needed washing (on the list). It seemed like it would happen especially after rough weather or after a period of running at low RPM.

Since about a month ago, I have had the problem of the engine refusing to rev over 3000. I was planning to wash the turbo this week. But now it's suddenly really bad again -- like two years ago. It might run up to 3000 briefly out of gear, but falls off again to 2300 - 2400. Will maintain 2300 -- 2400 in gear, but seems to stumble. At 2200 it's better. It happened at a nerve-wracking moment -- just as we were passing through a narrow gap in the rocks on the NW side of Brehat. And it happened after a series of hard rolls from the swell.

I am afraid it might fail altogether, then I would be in a nice pickle in this challenging place -- 14 meter tides and rocks as far as you can see. I don't even know where to look for a Yanmar engineer (or parts) around here -- maybe in St. Malo, or maybe make a run for Jersey in the West wind we have now.

The first thing I did was check the Racors -- clean as a whistle (as always -- we get good fuel around here) and not a drop of water. I have dual Racors with the vacuum gauge -- I switched to the other filter. No change. And no vacuum shown, which leads me to believe that there is no problem downstream of the Racors (or downstream of the lift pump, I guess).

There is no unusual smoke, temperature fine, oil pressure fine.

What could it possibly be? Here are my principle suspects so far:

1. Probably not turbo -- otherwise the engine should rev ok or at least much better out of gear, right? At this moment it makes little difference whether there's a load or not.

2. Lift pump? If the lift pump is not getting fuel through, that would account for these symptoms, it seems to me. But there is no fuel in the oil -- classic symptom of a bad lift pump.

3. Air leak in the fuel system somewhere? There are no fuel leaks, no bubbles in the Racors. But I will try bleeding the fuel system and see if that helps. We changed the fuel filter a few weeks ago and it made no difference in this problem.

4. Bad governor? Do those things go bad?


Anybody have any ideas?

I'm piping in a bit late here, been out cruising, but have you checked your exhaust hose. It's not a very common problem but sometimes the inside of the hose will delaminate causing an internal restriction/bubble, creating back pressure. All it would take is a lot of movement while the water/air is flowing.

[SailorHarry]

Hi, Google Ocean Navigator Magazine and look in the July 2011 issue for my article on rebuilding my lift pump. Good luck. SailorHarry

[Dockhead]

Originally Posted by delmarrey

I'm piping in a bit late here, been out cruising, but have you checked your exhaust hose. It's not a very common problem but sometimes the inside of the hose will delaminate causing an internal restriction/bubble, creating back pressure. All it would take is a lot of movement while the water/air is flowing.

Thanks! Didn't think of that - a hot tip. I'll check it.