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Yanmar 4JH4AE starting problem

Mistroma

Well-known member
Joined
22 Feb 2009
Messages
3,575
Location
Currently in Scotland, boat in Greece (Ionian)
I put the following on a Jeanneau forum but thought I'd put it here as well as it relates to Yanmar engines and isn't just a Jeanneau problem.

I know that it affects "a few 54HP engines made in 2008" (according to Yanmar). However, it may affect others which have a priming pump on the fuel filter and tank fitted lower than the engine.

*******************
Symptom: Engine needs a lot of throttle to start and then dies immediately. Problem only evident when engine has not been started for several hours.

Engine affected :4JH4AE 54HP (& possibly larger HP versions up to 110HP) circa 2008. Only versions with fuel filter priming pump (see picture).

The engine on my 2009 42DS (built 2008) became difficult to start after only 2 seasons. The engine would start but immediately die and then required full throttle and some cranking to get it running.

The problem seemed to be due to air in the system but everything from tank onwards seemed tight & leak free. The engine would start perfectly if it had been run in the past 10 hours or less.

I reasoned that the shaft seal on the pump might be passing air as the tank is fitted lower than the filter. To test this idea, I bled the system and plastered grease around the pump shaft. It worked perfectly for about a week. I also ran into someone who had reported the same problem to his Yanmar dealer. He confirmed that it was a known problem on some engines made in 2008 (and other years for all I know).

Yanmar fixed the problem under warranty and said that it only affected a few 4JH4AE engines. However, I've spoken to 2 other owners with same problem so thought that it would be worth sharing.

My engine now starts perfectly without touching the throttle. No selecting full throttle, trying to start and then wiggling the throttle to keep it running.

The "fix" was to replace the small priming pump on top of the fuel filter. The new unit has a "T" which bleeds air back to the tank return line. Filter changes used to require bleeding by use of the priming pump and bleed screw. I think that the new version just needs the ignition circuit on for a few minutes until the electric pump pushes all the air out.
 

noelex

Well-known member
Joined
2 Jul 2005
Messages
3,661
I had the same problem a year or so ago.

I posted this on another forum.Which may help


Solution to Yanmar 4JH4AE starting.

Background

My Yanmar has had starting problems since new. These 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 fuel system, such as the primary fuel filter, many of them several times produced no improvement

Service bulletin

Then I came across this service bulletin issued by Yanmar. The air leak was on the engine not the peripheral components.

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 50 HP engine use a different secondary filter system.
Why some and not all 4JH4AE are effected is not clear.

Solution

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


Fitting the part

The new filter housing is a direct bolt on for its predecessor. Some of the fuel hoses need changing, but anyone with a little knowledge could do this.
There were no instructions with the part, but if you download the 4JH5E manual, the fuel hose connections are obvious.
The system for bleeding the engine is also completely changed, but this is also covered in the 4JH5E manual.

Problem solved
Given this was an intermittent problem it will take some time to be sure that it is fixed, but I am confident that my starting wows are a thing of the past. I will certainly post if this is not the case.


Update : I can confirm it has fixed the problem


Links

Here are some links on previous posts on this issue.
http://www.cruisersforum.com/forums/f54/54hp-yanmar-starts-on-3rd-or-4th-try-42795.html

http://www.cruisersforum.com/forums/f54/yanmar-starting-21329.html

http://www.cruisersforum.com/forums/f54/yanmar-unresponsive-42798.html

This is a photo of the new filter
 
Last edited:

kyleview

New member
Joined
13 Feb 2011
Messages
176
Location
Scotland
Interesting - I had this problem in early 2008 when I bought a new boat with this engine. The Yanmar agent in Falmouth also noticed during the first 50 hour service and contacted Yanmar, but never got to the bottom of the problem. It just then disappeared and luckily I have not seen since. I now service the engine myself and after changing the filter and priming all seems OK. I am going to print off the above 2 posts and put in my engine folder for reference!

Thanks
 

svhoneybee

New member
Joined
14 Oct 2013
Messages
3
Location
Hobart
An old thread, but I am now experiencing the same problem with a 4JH5E, installed in 2011. Bleeding the fuel system doesn't help. The problem started after a standard service, a year ago when the engine had done about 650 hours. Anyone else experienced this witha later model engine? Any hints?
 

noelex

Well-known member
Joined
2 Jul 2005
Messages
3,661
The problem on the 4jh4AE was cased by a defective seal on the priming pump this was changed for 5E so you will not have the same problem.

Air in the fuel system can be very frustrating to track down so I feel your pain.

If it happened after a service I would suspect the primary fuel filter letting in air. What sort of primary filter do you have? Some of the CAV style filters can be especially hard to seal properly when a filter is changed.
 

svhoneybee

New member
Joined
14 Oct 2013
Messages
3
Location
Hobart
Noelex, the filter is a CAV, but I didn't change it with the last service. As I only changed the filter that is mounted on the engine, I am left thinking that the problem is there. I thought that these engines were supposed to be self bleeding, but it doesn't seem to work in my case (or maybe it does - the engine runs fine once it is going). I'll have another go at manually bleeding it.
 
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