Yanmar Starting

[noelex 77]

Originally Posted by never monday

I'd like to know if the electric pump continues to run as the engine is running. If you electrically isolated. The electric pump may be pressurizing the system initially and then stopping.

The fuel pump is clicking and on the whole time the engine is running.
An update, we have not run the main engine much lately, but the problem remains. I tried bypassing the fuel shut off valve and leading new fuel hose all the way back to the main tank. No difference. As I mentioned before the problem remains unchanged with 2 different types of primary fuel filters.


Still to try some of Dans suggestions, but unfortunately I bypassed the fuel shut off valve before I read his post. The problem is seen only after the engine has been shut down for a day or so. So each idea has taken some time to try.

In summary everything from the electric fuel pump back to the tank (The suction side) has been changed with no alteration. The problem to my thinking must be in, or after, the electric fuel pump, but this should produce a fuel leak and I cannot find a fuel leak. Still puzzeled

[Vedat]

I have exactly the same problem in my 4 JH4AE 54 HP Yanmar engine. Starts and dies in 5 seconds. Only way to keep the engine going is raising the idle speed to almost 75 % of FOT. Next month, it's going to be a full year with no solution. Worst is, during this time, Yanmar dealer, with the permission of factory as he said, has changed the sealed settings of high pressure pump many times. It effected the efficiency of the engine negatively, but problem stays same. I told the dealer that it looks like there is air in fuel system, but he rejected. I still insist that there must be a tiny crack in the lines or possibly in fuel filter which doesn't lead to a visible fuel leak.

Originally Posted by noelex 77

I have just installed a new Yanmar 54hp engine. It is running beautifully apart from a slight problem when starting. It will start immediately run for a few seconds then stop. It is then slow to start (5seconds or so of cranking) then runs perfectly.
My diagnosis is that there is a small air leak in the fuel system.
I have swapped the generator fuel line for the main engine and the problem persists. This eliminates a leak in the primary fuel filter fuel shut off valve etc.
This means the leak must be in the high pressure part of the fuel system so a leak should be visible but after a very careful look I cannot find any fuel leak. I have also tried tightening the secondary fuel filter and all hose clamps on the fuel lines.
Where should I go from here any suggestions appreciated. Is it possible there is some other problem? OR some internal leak?
The engine installer was fantastic but I would have to turn around and backtrack to get back to him, so I would like to solve the problem myself if possible.

[noelex 77]

Originally Posted by Vedat

I have exactly the same problem in my 4 JH4AE 54 HP Yanmar engine. Starts and dies in 5 seconds.

Thanks for the input. Let me know if you find a solution. I have completely changed the "boat side" of the fuel system, and it seems the problem remains, although it seems to have gone intermittent, if the engine is started every day its mostly OK, but when left for a few days it usually displays the symptoms.. This sounds better, but really only makes only it harder to track down.
There are some excellent technical people on this site and I am slowly working my way through all their suggestions, but it sounds like there may be some internal fault.

[Vedat]

Originally Posted by noelex 77

Thanks for the input. Let me know if you find a solution. I have completely changed the "boat side" of the fuel system, and it seems the problem remains, although it seems to have gone intermittent, if the engine is started every day its mostly OK, but when left for a few days it usually displays the symptoms.. This sounds better, but really only makes only it harder to track down.
There are some excellent technical people on this site and I am slowly working my way through all their suggestions, but it sounds like there may be some internal fault.

What type of fine fuel filter you have in your engine? Does it have a manual pumping button for bleeding on top?

[noelex 77]

Originally Posted by Vedat

Does it have a manual pumping button for bleeding on top?

Yes large push button on top of secondary fuel filter.

[Vedat]

Originally Posted by noelex 77

Yes large push button on top of secondary fuel filter.

I never understood the use of a manual bleeding pump on fuel filter though there is an electrical lift pump to bleed air in case. So I suspect there is something wrong with either electrical pump or fuel filter. Looks like they don't cope each other. Let's stay in contact.

[noelex 77]

Originally Posted by Vedat

Let's stay in contact.

Happy to hear any theories. I we let you know straight away if I solve it.

[Vedat]

Originally Posted by noelex 77

Happy to hear any theories. I we let you know straight away if I solve it.

Replacing secondary fuel filter with the one having no push buttons at top seems to solve the problem. Keep the filter element, change only the bracket with the proper one. After lots of wrong trials, that's what the factory recomended this time. My engine starts fine for the last 3 days. Hope this is the final and real solution.

[noelex 77]

Thanks. I hope this is a permanent solution.
How did you get a fitting for the secondary fuel filter without the push button.
Is it a Yanmar part? did they just seal off the top?
Thanks John

[Vedat]

Originally Posted by noelex 77

Thanks. I hope this is a permanent solution.
How did you get a fitting for the secondary fuel filter without the push button.
Is it a Yanmar part? did they just seal off the top?
Thanks John

Needs some time to say it's the permanent solution. Let's hope so. Local Yanmar dealer replaced the filter bracket with some other Yanmar model's without a push button. Then screwed the existing black cylindirical filter element to this new bracket. It has 2 inlets, one to be used as a bleeding screw, and outlet in the middle of these 2. They experience the result with mine, and if it's OK, they are going to replace all the others whether they suffered from this problem or not aware yet, they said.

Hope this also helps you.

Vedat

[Vedat]

Yanmar failed again. 4JH4AE dies at idle unless you start engine with a quite high RPM. Replacing the fuel filter didn't work. It's been almost a year and Yanmar couldn't be able to diagnose the cause.

[noelex 77]

Originally Posted by Vedat

Yanmar failed again. .

Sorry to hear that. I thought you may have found a permanent solution.
To clarify the symptoms with your engine, is it only starting that causes a problem, like mine, or do you have problems once it is started successfully?

[Vedat]

Originally Posted by noelex 77

Sorry to hear that. I thought you may have found a permanent solution.
To clarify the symptoms with your engine, is it only starting that causes a problem, like mine, or do you have problems once it is started successfully?

When it starts once, I didn't experience any problem during operation.

[Vedat]

Replacing the separator with a Racor type seems to solve the problem, at least up to day. I guess old seperator sucks air in.

[gvolos]

Hi all. Could any of you nice fellows that have experienced this problem tell me if they have found a permanent fix?
Sounds like a mind blower.
Thank you.