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Old 19-07-2012, 02:56   #1
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Yanmar Problems

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?
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Old 19-07-2012, 03:16   #2
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Re: Yanmar Problems

Have you checked your air filter?

Is there an in tank filter or gauze

my guess is fuel related
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Old 19-07-2012, 04:36   #3
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Re: Yanmar Problems

Yes, I think certainly it is fuel related -- as it usually is with diesel engines.

I have removed the air filter wire mesh and it runs the same.

I have now inspected the turbo -- it does not seem to be stuck. It turns by hand and at idle the turbine is already spinning. The impeller blades were slightly dirty so I washed them according to the Yanmar instructions. I washed the filter gauze. There was a little oil in the air filter but not enough to gum up anything, I don't think.

I don't know what's inside the tank -- it's very inaccessible. I had the tank cleaned when I bought the boat, and I've never had a drop of water or any dirt in my Racors. I don't think that it could be a blockage there or else the vacuum gauge on the Racors would show a vacuum.

I am thinking maybe really it's the lift pump, but I checked again and the oil is clean, no diesel in it.
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Old 19-07-2012, 06:01   #4
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Re: Yanmar Problems

A couple of more data points:

1. Oil is seeping out of the turbo. Not a lot. But the oil in the air cleaner which we had all thought was coming from the breather seems maybe is coming out of the turbo. Bad seal? So maybe the turbo is getting gummed up after all? Today I am getting about 3400 rpm without a load and about 3150 with a load. The turbo doesn't seem to be whistling as sharply as it usually does -- I might be imaging that, or then again it might not be spinning up like it should.

2. I can't find the lift pump! It must be electric, and must be with the tank somewhere (the tank is really hard to get to; built into its own space which can be accessed only by taking out the microwave). If this is true, then it means that the vacuum gauge on the Racors is meaningless. So it could be possible that the fuel pickup is clogged. Seems unlikely, as there is no gunk in the Racors -- you would expect some crap to get through, wouldn't you? But I thought I could prove that this is not the case, based on the vacuum readings, but if the lift pump is between the Racors and the tank, then all bets are off.
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Old 19-07-2012, 06:36   #5
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Re: Yanmar Problems

It does seem odd that even out of gear you can't get more revs and I would think even with a turbo problem out of gear it should still rev. I like to try the simple things first. Make sure that you are getting full throttle travel. It might have slipped. If it's happening with heavy rolling look also for "stupid" things like something moving that might be catching the throttle cable or maybe something pinching the fuel line when the boat rolls. If it's a mechanical engine and you have the workshop manual you should be able to check the govenor settings.
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Old 19-07-2012, 06:55   #6
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Re: Yanmar Problems

Quote:
Originally Posted by Dockhead View Post
A couple of more data points:

2. I can't find the lift pump! It must be electric, and must be with the tank somewhere (the tank is really hard to get to; built into its own space which can be accessed only by taking out the microwave).
I think the fuel pump is the same as my 4JH4AE. If so it is electric and looks like this.

The service handbook is here
http://www.scribd.com/doc/44874027/Y...Service-Manual
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Old 19-07-2012, 07:18   #7
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Re: Yanmar Problems

I once had a piece of black gunk clog up my fuel line. The filter was pristine. It clogged it at the 90 deg. bend at the top of the fuel tank. You would notice that by the vacuum gauge if you don't have an electric fuel pump pushing fuel into the racors (which you should not have). Racors are built to be on the low pressure side of a fuel pump.

Could it have anything to do with the level of the fuel in the tank? The bit about it happening after rough water could point to something in the tanks. Possibly something else but I don't know what. Have you checked that the fuel valve is opening all the way, is the throttle cable connection tight and adjusted properly?
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Old 19-07-2012, 07:45   #8
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Re: Yanmar Problems

My guess is gunk in the fuel tank....Gets stirred up in heavy motion otherwise it sits on the tank bottom doing no harm...
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Old 19-07-2012, 07:54   #9
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Re: Yanmar Problems

I forgot to ask whether your vacuum gauge has a needle that gets set to the highest vacuum reading? If it does not then it could still be gunk in the tank.
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Old 19-07-2012, 17:05   #10
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Re: Yanmar Problems

Quote:
Originally Posted by DeepFrz View Post
I once had a piece of black gunk clog up my fuel line. The filter was pristine. It clogged it at the 90 deg. bend at the top of the fuel tank. You would notice that by the vacuum gauge if you don't have an electric fuel pump pushing fuel into the racors (which you should not have). Racors are built to be on the low pressure side of a fuel pump.

Could it have anything to do with the level of the fuel in the tank? The bit about it happening after rough water could point to something in the tanks. Possibly something else but I don't know what. Have you checked that the fuel valve is opening all the way, is the throttle cable connection tight and adjusted properly?
Throttle cable is fine, and there is about 400 liters of fuel in the tank. Neither of these problems.

Fuel valve is a good tip. I have an emergency shutoff in the lazarette. I'll check that tomorrow.
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Old 19-07-2012, 17:34   #11
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Re: Yanmar Problems

Turbo Charger. It is driven by oil. Leaking, Look there IMHO
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Old 19-07-2012, 17:34   #12
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Re: Yanmar Problems

To eliminate a clogged tank intake pipe, run the engine via the Racor outlet hose in a bucket of clean diesel. Also run the injector return line hose into a clean container and look for contamination or bubbles coming out of it.

If the engine runs OK at full speed under load, then you can suspect a clogged fuel pipe. I've cleared them by blowing back through the hose into the tank, sometimes using a bicycle or dinghy pump when there's a heavy blockage.

In some cases I've removed the inlet pipe and fabricated a coarse filter around the end to capture blobs of goop that can be a result of biocide conditioning encountering a lot of water. I also pump out the tank with a long reach stirrup pump scouring the tank bottom, usually through the fuel sender aperture if there are no inspection ports. All the garbage lies on the bottom of the tank, sometimes defeating a fuel polishing rig.

This simple procedure will at least eliminate one problem area, easy to fix if it is the primary problem.
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Old 19-07-2012, 17:39   #13
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Re: Yanmar Problems

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Originally Posted by rtbates View Post
My guess is gunk in the fuel tank....Gets stirred up in heavy motion otherwise it sits on the tank bottom doing no harm...
yeah, that's where my money is too.... pickup tube in the tank gets clogged. Could even be something left in t he tank when manufactured....
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Old 19-07-2012, 17:42   #14
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Re: Yanmar Problems

If you have oil in the turbo you have a problem with the oil pump, and you should scrape out all of the carbon in the turbo and check seals as it will cause power loss, (recently had the same problem with the diesel in my truck) and you should drain all fuel from the tank, stem clean it, and check all the hoses and connectors to ensure there are no blockages such as algae that would allow some fuel through but become worse the more pressure is put on it. It may seem like allot of work but it is worth looking at.
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Old 19-07-2012, 18:27   #15
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Re: Yanmar Problems

Yeesch... Lets not get ahead of ourselves.....

No vacuum noted on the Racor= eliminate everything from there to the tank... EXCEPT a possible air leak>>>> Pressure test the line from injection pump to tank

Yanmars will certainly not turn up under load with a clogged turbo/intake, but will almost always hit the rev limit when full rack/no load. The 4 cyl engines have always had an issue with turbo corrosion from salt "humidity" once shut down because the mixing elbow is so close.... BUT the turbo is free spinning and the intake is clear, so forget the air side for now.

Going back to fuel and air... I would think that an air leak bad enough to limit your RPM under load would also make the engine nearly impossible to start, which brings me back to fuel restriction.

As mentioned previously, perhaps the throttle is not opening fully due to a linkage issue>>> Disconnect the cable and run her up manually at the injection pump.
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