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YANMAR 4JH3-HTE Diesel Engine RPMs drop and then it quits
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YANMAR 4JH3-HTE Diesel Engine RPMs drop and then it quits
We ran under engine for 30hrs motor-sailing from Brunswick GA to Chesapeake Bay. We turned the engine off when we got a bit of wind to sail. It was off for an hour. Running one hour it first time suddenly reduced RPMs and died. First thought was that we caught a fishing line. But that didn't seem to be the case. We started the engine again and it ran fine under load for a couple of hours then it failed again reducing RPMs. I took it out of gear, put the Morse throttle more forward, it didn't speed up and died. We continued under sail for two more days. It failed a few seconds after starting and trying to increase RPMs w/o load except for the alternator. I have checked so far: RACOR fuel filters are clean and no water. I have not switched to the alternate RACOR filter. The ONAN Gen-set ran fine several times for one to two hours each since the first engine failure. It feeds from the same fuel line. I checked the fuel filter at the YANMAR engine. - no air bubbles when bleeding and pumping with the manual pump - no debris and no water from the bottom drain valve - the fuel sensor shows open for both cases, engine off, engine running and dying. The panel doesn't show an error light even with switch disconnected, open ended or short circuited. I don't know whether it is wired up at all or lamp is dead. - I disconnected, cleaned contacts, and reconnected the magnetic shut off valve connector. My assumption is, that the magnetic valve only shuts off fuel while activated by pushing the STOP button on the panel. - Engine temperature always was around 80°C - Oil and cooling liquids are all looking healthy - engine fails with and without mechanical load - the engine is from Year 2003 and has 2750hrs - we had the engine serviced a week before we sailed: engine oil changed, fuel filters checked, main engine belt exchanged, impeller changed. The mechanic didn't put the new quarter $ size rubber disc. I installed it later. Visual inspection after we experienced failure I discovered that the starboard forward engine mounting bolt is rusty; looking above I found a small corrosion caused water leak of the elbow water mixer for the exhaust, just below where the flange/pipe from the turbocharger comes in. This seems to be a few drips only and must have been going on for a while given how rusty the engine mount nut and bolt look. So I don't think this is the root cause of my problem. We are now anchored south of Fisherman's Island at the mouth of the Chesapeake Bay near Cape Charles in a calm. Outlook for some wind tomorrow evening. I am running out of ideas and looking for suggestions from fellow AMEL owners. -- Michael & Robyn SY RIPPLE SM2K # 417 |
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On Mon, Jun 8, 2020 at 10:15 AM, Michael & Robyn wrote:
YANMAR 4JH3-HTEHere's a link to a discussion of, seemingly, the exact same problem / same engine. Perhaps some useful thoughts. https://www.cruisersforum.com/forums/f54/yanmar-4jh3-hte-187238.html Good luck with it. Craig |
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Michael, What you are experiencing must be a loss or restriction of fuel. I am curious why you did not switch to the other Racor filter. The Onan uses half the amount of fuel and uses an electric fuel pump. I believe it is possible that it could have enough fuel while the Yanmar may not. Also, you said that you checked the Yanmar filter. I do not think that visual checks of this filter are possible. I will attempt to list all of the possibilities for restricted fuel...maybe some that you have not thought of Order: beginning inside the fuel tank:
I hope that this helps you. Hopefully, someone else will add to this if I have left something out.
On Mon, Jun 8, 2020 at 10:16 AM Michael & Robyn <SY_RIPPLE@...> wrote: YANMAR 4JH3-HTE Diesel Engine RPMs drop and then it quits |
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Michael, You may test the fuel system flow if you press the manual pump on engine filter while running down. If the rpm is increasing again, replace first all your filters. Giovanni Testa Sv Eutikia SM2K 428 Il Lun 8 Giu 2020, 17:16 Michael & Robyn <SY_RIPPLE@...> ha scritto: YANMAR 4JH3-HTE Diesel Engine RPMs drop and then it quits |
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Giani, That is an excellent idea.
On Mon, Jun 8, 2020 at 1:21 PM Giovanni TESTA <giovannitesta53@...> wrote:
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Thank y'all for the suggestions and the link.
This morning I rechecked the probe I took from the engine fuel filter. It was sitting overnight in a small glass jar with a sealed lid. In daylight I was able to spot a ~3mm diameter water bubble at the bottom of the jar. I took probes from both RACOR filters. The unused one was clean and no water. The other one had a bit of dirt and added a few more very small water bubbles to my jar. Bill, you asked why I didn't switch to the other RACOR filter. First the filter didn't look dirty from outside shining a flash light against it. Second the pressure gauge was showing no significant low pressure. And in case of dirt in the fuel I wanted to keep the second filter as my last reserve for a docking under engine maneuver. We ran the Onan Gen-set last night again for an hour. Today I did bleed the fuel with the manual pump again. Cleaned the air intake filter, which did not really show significant dirt. I started the engine and it would run for a few seconds without load except the alternator. I tried several times. It would start at the second attempt and run for 10 to 20s and then drop RPMs. Putting the throttle forward made the engine speed up. But it would not last and die. One could hear that it was running on one or two cylinders. I ran the Gen again for an hour to keep batteries charged. Then a few more attempts. When the RPMs where dropping I put throttle forward. Finally I succeeded trying to keep it at 1500 RPMs. After 10 to 15 min it sometimes speed up to 1625 ... 1650 RPMs. After 30 min it run constant at 1650 with the initial throttle setting that gave 1500 RPMs. One could occasionally hear a missed ignition. After a total of 45 min the engine ran fine still at 1650 RPM. Since batteries where charged to 90% I reduced to idle for a few min and the engine ran smooth at 850 RPM until I shut off. We will see how it behaves tomorrow. I observed a small puddle of diesel fuel at the rim of the manual pump which I had hit by accident diving for probing the RACOR filters. My current assumption is that I have a small air leak in the fuel lines, maybe the manual pump itself. Or the air was introduced when the mechanic checked the RACOR filters. To Giovannis point, I had pushed the manual prime pump to help the engine start. Will send an update tomorrow how it went. Thank you and kind regards -- Michael & Robyn SY RIPPLE SM2K # 417 |
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Paul Dowd and Sharon Brown
Could I ask for some clarification on the use of the Racor filter gauge. My understanding is that this is a vacuum gauge and the higher the reading the more fuel blockage there is. Reading below runs counter to this interpretation. So how does one read this gauge and at what reading should I be concerned enough to swap filters?
Cheers, Paul S/Y Ya Fohi - Amel 54 #98 - Grenada
From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of Michael & Robyn
Sent: 08 June 2020 22:45 To: main@AmelYachtOwners.groups.io Subject: Re: [AmelYachtOwners] YANMAR 4JH3-HTE Diesel Engine RPMs drop and then it quits
Thank y'all for the suggestions and the link. SY RIPPLE SM2K # 417 -- Cheers Paul Ya Fohi - Amel 54 #98 |
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Hi Michael & Robyn, This won't be new info, but will reinforce Bill's thoughts. I've had similar problems twice in the last 11 years if ownership. The first time was very much like your problem. It turned out to be a very small leak in the fuel line that never dripped fuel, but sucked air when rpm got over 2K. After I ran out of ideas, a mechanic bled the injector connections and saw a few bubbles. It took going through the entire fuel system to find the problem. I wonder now if I could have pressurized the system and found a leak. The second time the Yanmar only died when we were motoring and running the Onan to use the microwave. The Racor fuel filters inspection bowls looked clean and free of water. I opened the second Racor and voila, problem solved. I cut the offending Racor open when we got to port, and found the filter material disintegrating. Before that I changed the Racors only every few years. Now the get changed at least every year and before a passage. Good luck, let us know what you find. Kent SM 243 Kristy On Jun 8, 2020 11:15 AM, Michael & Robyn <SY_RIPPLE@...> wrote: YANMAR 4JH3-HTE Diesel Engine RPMs drop and then it quits |
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James Alton
Paul,
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Most of the vacuum gauges that I have seen used on filter installations show a yellow band starting at around - 6 psi but that is not engine specific, just general. In my experience, with clean filters the drop should be almost nothing with the size engines we have and the correspondingly relatively small fuel flow. I have replaced a number of these vacuum gauges that were not functioning properly so I don’t actually have much faith in them. I do think that you are likely on the right path and are getting very good advice here. An air leak or a restrictive filter can certainly cause the symptoms that you are describing but there are other possibilities, a plugged fuel pick up tube, bad injection pump etc. . If changing the filter and trying to fix the air leak does not help, consider bypassing as much of the fuel system as you can to see if that corrects the problem to narrow things down. Running the engine from a jug and a short fuel line connected to the fuel pump can sometimes help reveal the true problem and to determine if the problem is with the engine or the fuel system. Best of luck to you. James SV Sueño Maramu #220
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Update on Fuel issue.
We ran the engine for a total of 14 hours on our passage into the Chesapeake Bay and up north to Cambridge MD. Three hours of these were at 2100 RPM. NO further issues. Thank you all for your helpful suggestions. I have no proof but the most likely explanation is that the air was introduced when the mechanic took the RACOR filters out for visual inspection and put them back in stating that they are in excellent condition and do not need to be changed. I assume our heavy rolling had pushed the air toward the engine. To James point I have a suspicion that our fuel vacuum gauge may have failed too. Given how little fuel our 100hp diesels consume and with a full tank I expect not much of a vacuum unless the filters would be really clogged badly. I consider to replace the mechanical gauge with an electronic vacuum sensor and wire it up to an instrument at the engine control panel. I still have to investigate why the sensor on the engine fuel filter doesn't show on the engine control panel. Reading Kent's post I will definitely change the RACOR filters and the engine fuel filter. My question now is how do you get the air out of the RACOR filters after changing the cartridge? -- Michael & Robyn SY RIPPLE SM2K # 417 |
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Hi Michael,
Just follow your RACOR manual (by the way, it is a RACOR brand filter, not a RAZOR filter) and that will tell you to unscrew the "T" bolt on top of the housing, remove the top, take out the old filter, insert the new filter, top off the bowl with clean diesel fuel, and then put the top back on. Very straightforward. Of course, having opened the fuel system you will need to bleed it before running the engine, which will also bleed any residual air from the RACOR filter housing. And Bob's your Uncle. Cheers, Craig |
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Mark & Debbie Mueller
To bleed the air out of the Racor after installing the new filter slowly open the Racor shut off valve allowing fuel to slowly gravity feed from the fuel tank into the filter bowl. I let the filter sit for a few minutes to allow any air in the filter element to escape, bring the fuel level to the top of the bowl, and put the cap on filter. I open the bleed screw at the Volvo and use the hand pump to insure that no air is in the system. I have done this when when changing the Rcaor by itself and when changing the Racor and the filter on the Volvo, No problems so far.
-- Mark Mueller Brass Ring A54 |
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Ian Shepherd
Michael, I had a fuel starvation problem with my Yanmar, but it was in starting, not whilst it was running, though I seldom use the engine other than for leaving and arriving at the dock. It was due to air in the engine fuel filter housing. I had changed the engine fuel filter, and whilst all looked well after bleeding, the problem was traced to the O-ring at the bottom of the filter housing. Having change the O-ring and made sure that it was properly seated, I have not had a problem since. You might want to check this area also as from what I read, your mechanic had taken the engine fuel filter off. Regards Ian Shepherd SM2K 414 Crusader -Cyprus On 14/06/2020 05:48, Michael &
Robyn wrote:
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