Bazz
New Member
Posts: 3
Jeanneau Model: Sun Odyssey 42i Performance
Yacht Name: Skywalker
Home Port: Port Shelter
Country: Hong Kong
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Post by Bazz on Nov 1, 2019 8:43:35 GMT
I have a Yanmar 54HP engine in my SO 42i which has been serviced regularly but has developed a starting problem whereby it will only start from cold with full throttle and the throttle pumped as soon as the engine fires. Even with this procedure the engine does not start every time. However, once started the engine runs very well. I have replaced the engine battery, the fuel pump and bled the system. Any thoughts on how to fix this would be very welcome.
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Post by MickeyB on Nov 1, 2019 8:51:23 GMT
Unsure on that exact engine, but check the temp sensor - the air mix is different on cold/warm engines.
Does it try to fire, or just turn over. Does it turn 'heavy' or normal?
Mike
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Post by MickeyB on Nov 1, 2019 9:08:48 GMT
Actually just remembered something - I once helped an old man who put ice cubes onto the injector pump. The engine then started happily - his conclusion was that something was getting stuck in there...
Or it could be a vapor lock, although some people think this is a myth so I am unsure.
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Post by Chris Meyer on Nov 1, 2019 13:41:31 GMT
We had a similar problem on a Beneteau 321 (Yanmar 3GM30).
Others did as well.
It is a poor design in the wiring harness between the starter button and the solenoid. Ran a wire straight from the starter button to the solenoid 15 years ago and never had that problem again.
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Bazz
New Member
Posts: 3
Jeanneau Model: Sun Odyssey 42i Performance
Yacht Name: Skywalker
Home Port: Port Shelter
Country: Hong Kong
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Post by Bazz on Nov 4, 2019 0:06:50 GMT
Many thanks for your thoughts.
The engine turns over normally and consistently. After a few seconds it fires but it does not continue to start. I have tried pumping the throttle at the instant it fires and sometimes it starts successfully and sometimes not. If not then you have to wait for a minute or two before trying again. Once it does start then it will tick over normally and run well. If you stop the engine after it has been running and restart, it will start immediately on tick over with no need for pumping of the throttle.
I think a vapour lock is possible but I have bled the system a couple of times with no improvement.
I have been told to switch the ignition on for 15 seconds to prime the pump before trying to start but this does not appear to make any difference.
Any other thoughts?
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Post by Syrah on Nov 4, 2019 1:17:29 GMT
It sounds a bit like what I experience just after changing fuel filters, i.e. during the period where I’m still trying to get rid of the last pockets of air from the system. (Diesel is a low volatility fuel and so this is not technically vapor lock. It’s really air lock).
The Yanmar engines in 42’s of that period are supposed to be self priming, so this shouldn’t be an issue after starting unless there is an air leak reintroducing the problem after stopping for some time.
Looking at a Diesel engine in simplicity and trying to step through each part:
Fuel is injected
Air is mixed
Compression ignites the charge
Exhaust out
If it’s fuel starvation
How long since the fuel filters were changed?
Is there a problem with one of the fuel filter seals leaking air?
Are the fuel lines in good condition, with good airtight connections?
Is it a problem associated with injector cleanliness?
Are there any issues with the air inflow control system? Cable loose? (Doesn’t really explain why it runs OK once started)
What is the ambient air temperature in your location at the moment?
Once running it will restart.
Is it perhaps a very cold environment and needs to use glow plugs prior to starting?
Injection timing issue? (I’d expect this would impact it running once started though)
Exhaust: valve condition? Probably a long shot, but perhaps check compression of cylinders as a final step if you can’t find anything else
What engine is it? JH4 series? I have a pdf of the service manual for this engine series if that would help
I’d be looking at the simplest reason first. To me that would be air getting into the fuel system.
Hope this helps. Good luck
Wayne
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Post by alex1949 on Nov 4, 2019 9:02:41 GMT
Hi Bazz
All suggestions are ok,all connections should be tight.
One thing that I would reccomNd is to bled not only the top point where we we always do but olso bled seperately all fuel pipes that goes from injection pump to all the cylenders.
Release the pipe just before it get connected to the cylender,than pump using the hand pump till you see no buble diesel flow and tigh pipe agsin while slowly hand pumping.Do same four lines.It happens to have air blocks trapped overthere sometimes.Try it and let us know if.....
Alex
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Post by John on Nov 4, 2019 15:45:50 GMT
Hi Bazz ,
This is a great Yanmar engine and boat , I hope you will get many years enjoyment from it .
I have serviced the same engine last week and had air in the system , if after changing the fuel filters there is air in the system remove the fuel return pipe then turn on the ignition ( but not starting ) let the air bubbles through until you see fuel only a small bucket needed to catch fuel , then reconnect the fuel return pipe and start the engine , easier if you have someone to turn the key . This is worth trying next . Maybe check all circlips are tight as well Hope this helps .
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Post by panoramix on Nov 4, 2019 16:47:46 GMT
If the engine runs well once started, fuel, air, filters, connections and timing are oke.
For starting you really need good battery and good compression. So my advice, do a compression test.
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Post by Mistroma on Nov 5, 2019 14:52:42 GMT
I know that some 54HP 4JH4AE versions had a small priming pump fitted on top of the fuel filter mount. The seals on the piston could leak and allow air back into the system. I had this problem many years ago. The engine became harder to start and required a lot of throttle. Re-starts would be fine for several hours before the problem returned. Yanmar confirmed that it was a known issue with the seals on some of these small hand pumps. I had a replacement filter mount fitted under warranty and this self-bleeds, so no pump required. The only difference in use is that you can't manually prime the filter after a filter change. I partially fill the new filter prior to fitting and then let the small electrical pump run to complete the process. It could be the source of your problem if there's a black button on the top of your fuel filter bracket similar to the one below.   |
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Post by pagoda54 on Nov 6, 2019 22:40:05 GMT
I know that some 54HP 4JH4AE versions had a small priming pump fitted on top of the fuel filter mount. The seals on the piston could leak and allow air back into the system. I had this problem many years ago. The engine became harder to start and required a lot of throttle. Re-starts would be fine for several hours before the problem returned. Yanmar confirmed that it was a known issue with the seals on some of these small hand pumps. I had a replacement filter mount fitted under warranty and this self-bleeds, so no pump required. The only difference in use is that you can't manually prime the filter after a filter change. I partially fill the new filter prior to fitting and then let the small electrical pump run to complete the process. It could be the source of your problem if there's a black button on the top of your fuel filter bracket similar to the one below. Is there any revised part number for the "improved seal" filter top housing - or have Yanmar simply altered the seals since introduction of the engine? Could the seals be replaced themselves? I see another project lining up! |
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Post by Mistroma on Nov 7, 2019 21:30:06 GMT
I asked exactly the same question about the part number for future reference. Unfortunately, the dealer was sent the part with no part number in the documentation and Yanmar weren't much help in providing a number. I checked the replacement carefully but could not see any numbers stamped on it. It wasn't a great concern because Yanmar fixed it under warranty.
I diagnosed the fault myself by simply thinking it through and came to the conclusion that an air leak was the most likely answer. I checked all connections and hoses without success. I reasoned that fuel would drain back from the engine as the tank is at a lower level. Any leak in the engine would suck in some air. The pump seemed to be a likely candidate. I could imagine air entering the seals around the piston rod but still sealing under pressure when the engine was running.
I tested this theory by pushing thick grease around the piston where it enters the pump body. It worked well and the engine started easily once more after sitting overnight. Of course this quick fix only worked for a short time but did prove that the pump was leaking air. Yanmar accepted this and said that they had seen the problem before.
I would probably have tried to dismantle the pump if it had not been a warranty issue. I expect it would be possible to replace the lip seals and fix the pump.
The trick with grease is a quick and easy way of checking the pump seals (assuming that you do have this small hand pump on the filter unit).
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Post by pagoda54 on Nov 7, 2019 21:45:09 GMT
Thanks for that additional info.
Looking at the Yanmar Parts diagrams/lists it would appear the "new style" as fitted to 4JH5 models is 129004-55612. Minus the plunger pump on top.
I think I'll strip the old housing down and look st the seals/materials etc.
Cheers, Graeme
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Post by Mistroma on Nov 10, 2019 1:10:55 GMT
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Post by alex1949 on Nov 10, 2019 8:45:19 GMT
I have a Yanmar 54HP engine in my SO 42i which has been serviced regularly but has developed a starting problem whereby it will only start from cold with full throttle and the throttle pumped as soon as the engine fires. Even with this procedure the engine does not start every time. However, once started the engine runs very well. I have replaced the engine battery, the fuel pump and bled the system. Any thoughts on how to fix this would be very welcome. Poor Bazz, did you manage to solve problem ? |
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Post by pagoda54 on Nov 10, 2019 18:42:57 GMT
My thoughts entirely! I can do quite a bit of investigation first, with the encouragement of that price tag! |
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Post by mistral54 on Nov 12, 2019 11:31:10 GMT
Hi Bazz
Ths may not help but I have a Yanmar 110hp. My probem was the exact oppsite of yours . Engine always started from cold but after stopping for lunch and the engine cooled it wouldnt start. We found that priming the engine on top of the fuel filter it would start. My mechanic looked for air leaks and couldnt find any issues so he suggested that we put in a small inline fuel pump which activated on the ignition so priming the fuel beore starting. I suppose you could try priming the pump before starting from cold and if it starts straight away that will be the problem.
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Post by pagoda54 on Nov 16, 2019 20:56:18 GMT
My thoughts entirely! I can do quite a bit of investigation first, with the encouragement of that price tag! I had a preliminary look at the top end of the suspect secondary filter/priming pump assembly. The priming knob simply operates a diaphragm under the top of the filter in a chamber with two small flap valves (in-out) from the filter element below. There is no sealing mechanism round the shaft of the push-primer pump. If any air is able to pass into the chamber below the diaphragm it can only be via a poor face seal or a leaky diaphragm. I have not checked the condition of the two flap valves yet. The diaphragm looks and feels good?? The sealing faces are clean and sound. Not the end of the story yet! Graeme |
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Post by sleighride on Nov 17, 2019 20:24:02 GMT
I had similar problem on a J30 (Yanmar engine) with inconsistent starting, even if engine was still warm. It turned out to be starter itself which had “flat spots” according to the shop where I had starter rebuilt. No starting problems after the rebuild. I have always carried a spare starter after that experience, but have never had a problem since we bought our DS43 in 2002.
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Post by Mistroma on Nov 18, 2019 23:06:03 GMT
My thoughts entirely! I can do quite a bit of investigation first, with the encouragement of that price tag! I had a preliminary look at the top end of the suspect secondary filter/priming pump assembly. The priming knob simply operates a diaphragm under the top of the filter in a chamber with two small flap valves (in-out) from the filter element below. There is no sealing mechanism round the shaft of the push-primer pump. If any air is able to pass into the chamber below the diaphragm it can only be via a poor face seal or a leaky diaphragm. I have not checked the condition of the two flap valves yet. The diaphragm looks and feels good?? The sealing faces are clean and sound. Not the end of the story yet! Graeme Good to know. I did manage a temporary fix by smearing thick grease around the base of the plunger. The only thing this could achieve was to reduce the flow of air down into the pump. It only worked for a week or two but confirmed the location of the issue. Yanmar were quick to accept that it was the cause and paid for replacement under warranty. The newer design had no pump and the dealer said that a batch of the older model were known to cause this problem. He mentioned air passing the seals and I just assumed that these were lip seals. I sounds as if the problem was most likely due to a leak in the diaphragm. The trick with grease would not have worked if air had not been leaking past the plunger. Interesting to get feedback on the actual design even though I no longer have one in my system. |
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Bazz
New Member
Posts: 3
Jeanneau Model: Sun Odyssey 42i Performance
Yacht Name: Skywalker
Home Port: Port Shelter
Country: Hong Kong
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Post by Bazz on Nov 21, 2019 1:04:05 GMT
Thanks for all your thoughts on my engine starting problem. I am still on the case and will be doing a full service this week although air leaks and priming the fuel pump appear to be the favourite culprits at the moment. Keep you posted.
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