Yanmar 4JH4-HTE - Hard to restart after 30 min

[WickedG]

Hello everyone.

First post therefore, I’d like to start by thanking everyone for the knowledge and experience shared throughout CF. It’s been really helpful.

Have a 110 HP Yanmar 4JH4-HTE. Engine will start with the turn of the key even after a month without using it. Don’t even need to preheat/glow (live in Florida, US).

Most of the times it will restart immediately when hot, BUT after 20 or 30 min, once its starts to cool down (and some times when hot as well), the starter will turn but engine won’t start.

It takes between 10 to 20 attempts to get it running again.

Some times it’ll start and will run at low revs (aprox 400 RPM). Revs wont increase even if I apply full throttle. After a minute or so, revs jump to idle (aprox 800 RPM) and everything works just fine.

As you can tell, I’m no diesel nor mechanic expert but I presume this has to be a fuel related issue. I can tell you my fuel is ok, filters are clean, hoses are ok. My mechanic also checked the wiring and everything seams fine.

As a side comment -and though I cant really say it helps- I “feel” that working the fuel Priming Pump somehow makes the restart process a bit easier.

NEXT STEP: Mechanic suggested replacing the solenoid (aprox u$d 300).

Does this make sense? Any other suggestions?

Thanks in advance for any help/comments.

[TheOffice]

sounds like a fuel supply problem - possible a tiny crack in a hose or fitting affected by heat from the engine. Could be a PIA to track down.

[sony2000]

It could be a starting to fail, fuel supply check valve.
Also as mentioned, try snugging up the connectors on the fuel supply lines.

[Snore]

Sounds like a fuel line leak. Engine starts from fuel close by. It stalls when the air trapped in the system gets to the engine. Your cranking is purging the air caught in the system.

From experience --- the low rpm (and sounding like crap) is when the first cylinder gets fuel. It fires, carrying the engine until the fuel supply line purges the rest of the air. Then rpms will go up as each successive cylinder gets fuel.


A few questions--

Is there signs that the solenoid has a leak?

How long have you had the boat?

How long has the problem been going on?

What work has been done on the fuel system? Replace or add filters?


Sent from my iPhone- please forgive autocorrect errors.

[Kokanee]

It does sound like air sucking into the fuel lines.
One tip of heard works well, though never tried it myself, is installing a temporary clear bit of fuel line at several points in your fuel lines. Check for any air bubbles in passing through each hose. Any bubbles will confirm the problem is upstream from there.
Clear hose on both the inlet and outlet of your solenoid will tell you if it is the culprit.

[unclemack]

Originally Posted by WickedG

As a side comment -and though I cant really say it helps- I “feel” that working the fuel Priming Pump somehow makes the restart process a bit easier.

NEXT STEP: Mechanic suggested replacing the solenoid (aprox u$d 300).

Does this make sense? Any other suggestions?

Thanks in advance for any help/comments.

Stop solenoid is certainly possible if it's beginning to stick - price sounds high but I don't know your engine. Check electrical contact is good first.
Next time it won't start try lightly tapping the solenoid body while somebody turns the key.

Other posters' suggestions are just as likely - better to diagnose by testing and doing the simple stuff - nipping up joints, nailing down by bleeding whether working the pump actually does help - rather than throwing new parts at it until something sticks.
Intermittent faults can be a pain to find though.

Mechanics these days often just replace this, replace that and then when and if it's finally fixed - you still get to pay for all the parts you didn't actually need.


_

[wiekeith]

I had a similar problem with my 4JH4AE engine. It turned out that Yanmar were aware of the problem and suggested a replacement secondary fuel filter housing. I replaced this and the problem went away.

This may not be your problem, but I thought it worth a mention - it took me a while to get the official information from Yanmar.


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.

[sailon46]

Same problem fixed it by changing the secondary filter, now engine puts out 4000 + no load, 3500+ load and no starting problems

[01kiwijohn]

Yep, sounds like it's losing its' prime. I really doubt the solenoid will fix that.
The new style yanmar filter is a consideration but I would start at the priming fuel pump. After all, the engine was running ok up until recently, right?
It has a couple of check valves, and a diaphragm. If the diaphragm is leaking slightly, it may show up as though the engine is "making oil". Pull the stick and take a look.
Otherwise, re-kit the pump, with new check valves and diaphragm. It is not a very difficult task, any auto mechanic should be able to do it in about 15 to 30 mins., once removed.
If happen to be in the Tacoma area, drop buy & I'll show you how.

[Privilege]

Another possibility is that you are getting a vacuum in your fuel tank due to a clogged air vent. When the engine is running, it sucks in the fuel creating a vacuum in the tank. When you turn off the engine, the vacuum sucks the fuel back away from the fuel pump. Try removing your fuel cap the next time you try to start it when warm.

[Snore]

^^^^^

Yup did not think of that.


Sent from my iPhone- please forgive autocorrect errors.

[WickedG]

Thanks everyone.
Tested all the above suggestions; still have the same problem.
I additionally tested blowing the return lines so as to verify there was no fuel clogging. Also opened the injectors and verified fuel was coming out (though I cant tell if the volume is correct).
My mechanic gave up. Looks like I'm headed to Yanmar's official service (Miami, FL area).
Any suggestions?
Thanks again.

[Privilege]

Maybe try getting a jerry can with clean fuel and running a hose directly from that to your fuel pump on the engine, priming it with the little priming lever on the side. (Don't worry about the return line). If you still have the problem then you can be sure that it's an engine problem. At least then you can eliminate the possibility of it being a problem with the fuel tank, supply lines, fuel filter etc.

[sailorboy1]

maybe consider just getting an electric fuel booster pump

[hpeer]

Originally Posted by Privilege

Maybe try getting a jerry can with clean fuel and running a hose directly from that to your fuel pump on the engine, priming it with the little priming lever on the side. (Don't worry about the return line). If you still have the problem then you can be sure that it's an engine problem. At least then you can eliminate the possibility of it being a problem with the fuel tank, supply lines, fuel filter etc.

To this I would add you could try the priming lever to see if you get immediate fuel coming out or air. That will tell you if the leak is on the fpdelivery or the secondary filter side.