Solution to Yanmar 4JH4AE Starting

[noelex 77]

*
Background

My Yanmar has had starting problems since new. These problems, are now fixed. This was my solution.

Symptoms

The engine would start run for a few seconds, then stop. Restarting involved a lot of cranking, or could only be done after bleeding the fuel system. Once started and running the engine ran perfectly. The problem was intermittent, sometimes OK for a month or so, then a month needing a bleed for every start.

Diagnosis

These symptoms or characteristic of an air leak in fuel system. Unfortunately changing every component in the peripheral fuel system, such as the primary fuel filter, fuel lines and fuel shut off valve, many of them several times, produced no improvement

Service bulletin

Then I came across this service bulletin issued by Yanmar. There was air leak at least on some engines at the secondary fuel filter priming pump. This is part is integral to the engine not the peripheral components where I assumed the air leak was occurring..

GLOBAL TECHNICAL BULLETIN

Ref No: GTB2009002
Date: February 9, 2009

GTB2008-002
To: XXX XXXXXX marine distributors
Subject: 4JH4-AE fuel system

Yanmar wishes to inform you, that we have found occasional starting trouble on our 4JH4-AE engine
series. After investigation we found that in some rare cases, air can enter the fuel system. The reason for
this was found in the fuel-filter with priming pump.

For this reason, Yanmar has decided to change the fuel-filter and fuel line specification for the new 4JH5
engine series.





Effected engines

The only Yanmar engine effected seems to be the 4JH4AE. Other Yanmar engines, including the earlier and later versions of the 54 HP engines use a different secondary filter system.
Why some and not all, 4JH4AE engines are effected is not clear.

Solution

Yanmar have completely changed the fuel pump on the new 4JH5 engine. This engine appears almost identical otherwise to its predecessor the 4JH4AE. Fitting the new secondary fuel filter housing from the 4JH5 on the 4JH4AE fixes the problem.
Part number: 129004 - 55612
There are no additional parts needed, other than some 8mm fuel hose.



Yanmars response

Disappointingly, particularly to known problem, I got no response from several emails to Yanmar.
On suggestion of this forum an email to Mack Boring and I suspect some pressure from forum members produced some action. Many thanks to Rick from Mack Boring and Mike fromYanmar Marine Division in the US and all who posted with helpful advice.
I was sent out the new secondary filter housing at no charge, despite my engine now being out of warranty (I had spent a year trying to track the problem down). They even couriered the part to me on a remote Greek island. That’s great service and I would now strongly recommend Yanmar again. After a slow start they kept this customer happy.


Fitting the part

The new filter housing is a direct bolt on for its predecessor. Some of the fuel hoses need changing, but it is simple pluming. The fuel return line needs to be a few inches longer so you may need to join this if there is not enough play in the existing hose,or replace the whole line as I did.
There were no instructions with the part, but if you download the 4JH5 manual, (in PDF format from the web site) the fuel hose connections are obvious. The technical drawings also available from the Yanmar web site are also useful showing in diagram form the new fuel connections.
The system for bleeding the engine is also completely changed, but this is also covered in the 4JH5 manual.
After the filter housing change the fuel system is the same as the 4JH5 and completely different from the 4JH4AE.

Problem solved
Given this was an intermittent problem it will take some time to be sure that it is fixed. Just before the filter housing change the engine needed bleeding for almost ever start. All starts with the new filter housing have been normal, with no other change so I am confident that my starting wows are a thing of the past. I will certainly post if this is not the case.

Links

Here are some links on previous posts on this issue.


http://www.cruisersforum.com/forums/...try-42795.html

http://www.cruisersforum.com/forums/...ing-21329.html

http://www.cruisersforum.com/forums/...ive-42798.html

[stacy]

Noelex77. i am sorry that you have had such a frustrating time with this problem. i hope you can derive some satisfaction from the fact that you have helped numerous boaters that now have a solution to the same nagging problem. thanks from KATABATIK

[gvolos]

Great job Noelex. Thank you you for a very clear and well written post. Are you still in Greece? If you are in the Athens vicinity perhaps we can go for a beer sometime.
Cheers.

[noelex 77]

Originally Posted by gvolos

Great job Noelex. Thank you you for a very clear and well written post. Are you still in Greece? If you are in the Athens vicinity perhaps we can go for a beer sometime.
Cheers.

Thanks I would love to catch up for a beer sometime.
In Milos at the moment, but planning to winter in the Argolic gulf with a trip to Athens hopefully. I will give you a shout if I am in the area.
.

[gvolos]

Great! Looking forward to meeting you.
All the best.

[Frizfalklands]

Many thanks for the write up and the Yanmar bulletin.
I am.just going along the fault issue with our very own engine.
We have had a few incidents over the last few years with this issue. And recently 3 separate days one afternoon the other. So now I have to see if Yanmar will honour the replacement part some 13 years after the vessel launch. However engine hours very low 965hrs.
Otherwise it's a purchase.
Again thanks for the info al.