Diesel Warm Start and Idle Problem - Yanmar 4JH3-TE

[sv.Crake]

I've got a strange problem and I'm looking for some ideas:


Engine: Yanmar 4JH3-TE


Symptoms in short:



1. When engine is hot after running under load for a few hours, Idle speed drops to very low RPM. Engine stalls when brought back to neutral (single control level so going back to neutral brings throttle back all the way).

2. Once it has stalled out this way, Engine will NOT start again till it has cooled down some. ~ 30min to 1 hour. It will crank fine but not fire at all. Once a bit cool, it fires back up no problem and Idle is back to normal.



In a bit more detail:

The engine initially starts and runs great, in and out of gear and idles fine at. Testing it at the dock I have no problems. The engine idles nicely. If I take the boat out and run it under load for a while when i bring the throttle back all the way now the idle speed is WAY too low and the engine struggles a bit and then dies. Once it stops, I can't start it till it sits for 30min - 1 hour. IT will crank and crank but not fire. WD40 down the air intake does not seem to help get it going. After a waiting period it fires back up perfectly, instantly and the idle is back to normal. Once hot, if i keep the throttle advanced further than normal (hard w/ single control lever) the engine is fine i can keep it running. But if i let it drop too low and it dies i am screwed and have to anchor and wait.



I bought this boat somewhat recently, previous owners never really used it much so i'm dealing with light use but heavy neglect.

Engine is 2001, only 500 hours on it. I had the high pressure fuel pump and injectors rebuilt recently. All normal overhaul stuff I have done. Fuel is super clean, etc etc.

[Stu Jackson]

Boating forums are funny: you never hear of a certain "something" and then all of a sudden there is a rash of questions about the same symptom. I've seen this question three times in the last week without ever having heard of the issue in the prior three decades!


Good luck.


https://forums.sailboatowners.com/th...hlight=obscure

[sv.Crake]

Thanks Stu. Can you link me to those threads. I've been hunting but not found them.

[GreenWave]

Is there a possibility your fuel pump is overheating or failing somehow? How did your engine behave before the work you did?

[HeinSdL]

I had something similar a couple of years ago. I am not sure exactly what happened but I think I had some air in the filter which expanded when the engine compartment got hot and the engine would cut out due to some air getting sucked in. No idea about the validity of this theory but in any case I then bypassed the primary filter completely, fuel supply line directly into the lift pump on the 4JH3E and the engine ran fine. I then replaced all the primary filter infrastructure plus added back up and a fuel conditioning system and have been OK ever since.


Edit: if you are cranking the engine excessively without it firing don't forget to close the raw water inlet...

[Andreas W]

This is one possibility. Another is that the problem is in the governor.

Originally Posted by HeinSdL

I had something similar a couple of years ago. I am not sure exactly what happened but I think I had some air in the filter which expanded when the engine compartment got hot and the engine would cut out due to some air getting sucked in. No idea about the validity of this theory but in any case I then bypassed the primary filter completely, fuel supply line directly into the lift pump on the 4JH3E and the engine ran fine. I then replaced all the primary filter infrastructure plus added back up and a fuel conditioning system and have been OK ever since.


Edit: if you are cranking the engine excessively without it firing don't forget to close the raw water inlet...

[sv.Crake]

Before the work - when i bought the boat it did not run at all and had not been run in 2 years. After getting it running it has had this problem. It has gotten less severe after running the engine for 100hrs but not gone away.

[sv.Crake]

I don't think its an air issue. I've re-done the whole fuel system from tank to engine and the problem has not gone away. (pressure washed tanks, new fuel lines, filters, etc etc)

[Stu Jackson]

Originally Posted by sv.Crake

Thanks Stu. Can you link me to those threads. I've been hunting but not found them.

My reply #2 was just that, I do not understand this^^^.


Here's the text of what I wrote in that link:


On September 20, 2019, I was motoring back from a few enjoyable nights at my favorite local anchorage when I experienced a fuel starvation issue for the first time in my boat. We have sailed Aquavite since 1998. The engine simply sputtered and died, would restart after a few minutes and die again. There were no previous issues, ever.

I replaced the fuel pump. I had corrected the fuel flow from the tank to the primary when we first got the boat. I replaced the primary filter last year. I replaced the secondary filter. When a test sail proved fruitless, I had to go further.

I remembered reading the Racor manual ages ago about a "fuel check valve" that's cleverly hidden at the inlet of the filter housing. It's called a ball check valve, which keeps fuel from emptying from the filter if the tank is below the filter, which makes sense. I undid all the new fuel hoses I'd just put in (!) for the new fuel pump and unscrewed the primary filter and bowl, and then removed the housing.

The filter housing is the Racor 220 / 225 Spin On Series, using the ubiquitous Racor R24 Series filters, installed on most Catalina 34 boats. On the top of the housing is a large plastic screw, identified in the manual’s first page diagram as the “Flow Check Valve” and on page four, it is replacement part list Item 3, part # RK20011, “Check ball valve and plastic cap.”

I unscrewed the check valve plug and O ring and found 33 years of accumulated tiny black particles that kept the ball from rising and allowing fuel to flow. It didn't take much crud at all to stop the ball from working properly. It's a very small chamber about the size of a quarter and the ball is smaller than a dime. There was actually no "bad fuel" issue, just decades of what I would consider to be normal stuff found in any liquid. I cleaned it out, and things are back to working properly.

If you have fuel starvation issues, or anything that reduces your engine RPMs, consider this obscure fuel filter housing ball check valve as part of your diagnostics.

PS The Racor 500 series housings do NOT have check valves in the housing, but the manual says to install a check valve in the inlet of your fuel hoses to the housing if your tank is below the filter.

[thunderhoof]

Are you sure there is no engine overheating or lack of lubrication oil? Although I agree that is probably a fuel delivery problem please check the water discharge for excessive steam and that the oil level is near the correct level. This really is a worst case scenario where the engine overheats to the point where it starts to bind up. I would hope that you would hear/see lots of alarms before this happens.

[Bravo46]

An off the wall suggestion, but look to see if there is a screen on the end of the pickup tube in the fuel tank. If there is any kind of junk in the fuel tank it will accumulate on the pickup screen and starve the engine of fuel. After a bit of time, the junk falls off and all is good again, until the fuel suction accumulates the debris again. Chuck the screen. That’s what Racors and primary filters are for.

[Reefmagnet]

It's possible that a bad injector pump can cause that issue. The 20-30 minutes before restart is a symptom. Something to do with changes in clearance with heat affecting fuel delivery.

[kish]

[QUOTE=Stu Jackson;3212670]My reply #2 was just that, I do not understand this^^^.

<snip>
PS The Racor 500 series housings do NOT have check valves in the housing, but the manual says to install a check valve in the inlet of your fuel hoses to the housing if your tank is below the filter.[/QUOTE]

This is not correct. Can you link to that manual that advises that?

The Racor 500 series have a check valve

https://www.parker.com/literature/Ra...ine_Series.pdf

[etoimene]

Interested in the subject. Similar issue of Yanmar 4JH4-HTE stopping in idle after long runs. I'll check the fuel filter first.

[hpeer]

Just to add another possibility, especially for Bosch Fuel pumps. I have a 4JH4. That has a wax timing advance, “cold start, anti-smoke” element. The element works much like a thermostat. When cold the timing is one way, when it warms up, the wax melts and the timing changes a few degrees. About 10° IIRC.

If the fuel pump timing were to out even a bit it would start but then shut down when the timing changed.

Your timing could be off so that it will not start when hot. It starts cold, warms up and runs, but will not start hot. It then needs to cool down again to restart.

In my 4JH4 there is a cooling water circuit that runs to the fuel pump, near the fuel adjustment, throttle linkage. At one point it rattled itself to death. And the anti-smoke timing advance was not working. Engine ran fine that way.

It’s simple enough to look at this critter and observe its action or inaction. And maybe you want to lay hands on the fuel pump to make sure it is secure. You adjust timing by rotating the fuel.

Just an easy thing to check.

File:BoschVE-coolantKSB.jpg
Coolant operated KSB fitted to a 2.1 Renault engine in a Winnebago camper
KSB 'Kaltstartbeschleuniger' Cold starting timing advance system.
First used 1975. A number of different methods are employed to advance the timing for cold starting and low speed cold running.
Mechanical System. A lever is pulled which turns a cam that pushes the timing piston to provide about 5 degree advance at no load. At above approximately 2200rpm this has no effect on timing.
Mechanical KSB seal replacement

'Wax Motor' system. A solenoid is activated but is held open by a wax plug that melts as the engine warms allowing the solenoid valve to close. While the valve is held open the transfer pump pressure regulation valve is overridden allowing higher pressure to be made within the pump housing. These higher pressures provide a 5 degree advance that reduces with engine speed. When the engine is stopped the power to the solenoid is cut, opening the valve. As the engine cools the wax solidifies.

https://www.appropedia.org/Bosch_VE