H49 engine stalls

Sep 20, 2006
155
Hunter 49 Mystic CT
I’m frustrated with my Yanmar 4jh4hte. The engine runs great, however after running for 30 minutes or more and I lower the RPM to drop into neutral and then into gear, the engine will stall. I’ll put it into neutral to restart it then into gear and it will stall again. Picture the routine of pulling into a slip. It will not stall if no load is applied so we (yard mechanic) thought it was the transmission so I had that pulled and sent out. No problem was found with the transmission and the problem still exists. As a side note if the engine and transmission is cold it runs and shifts great. I also dove on the prop to see if it was fouled (Variprop ) unfortunately it was not. So I’m stumped any ideas would be appreciated
 
Jun 1, 2009
1,363
Hunter 49 toronto
Possible idea

I’m frustrated with my Yanmar 4jh4hte. The engine runs great, however after running for 30 minutes or more and I lower the RPM to drop into neutral and then into gear, the engine will stall. I’ll put it into neutral to restart it then into gear and it will stall again. Picture the routine of pulling into a slip. It will not stall if no load is applied so we (yard mechanic) thought it was the transmission so I had that pulled and sent out. No problem was found with the transmission and the problem still exists. As a side note if the engine and transmission is cold it runs and shifts great. I also dove on the prop to see if it was fouled (Variprop ) unfortunately it was not. So I’m stumped any ideas would be appreciated
Maybe your dripless coupling is jamming the shaft.
Put the engine in neutral, and see if the shaft rotates freely.
Other possibility is something jammed in the cutlass bearing
 
Sep 20, 2006
155
Hunter 49 Mystic CT
Artboas- thanks we have checked the shaft and the dripless coupling when we pulled out the transmission. The shaft spins no problem.

Have not thrown a tack to confirm the idle rpm. Its worth a try.

I have heard of the 4jh4HTE having fuel pump issues which is really where my thinking is going right now. If anyone knows what the symptoms are of of a failing fuel pump, I'd love to hear them.



Thanks
 
Jun 4, 2004
287
Hunter 49 123
When was the last time your cleaned/serviced the turbocharger? Also check idle rpms. Mine slipped below 700 rpms making it difficult to stop using the red button and stalling as you describe.
 
Feb 21, 2009
4
2 49 Waukegan, IL
I had what sounds like the same problem with the same engine in my Hunter 49. After the engine ran for an extended period, it would usually stall when brought down to idle speed. Sometimes it would go into neutral without stalling but then it would stall when shifted into gear. Sometimes it would restart right away but often it would not start until it had rested for 30-45 minutes.
After trying all of the things that have been mentioned, and more, over a period of several years, the Yanmar Distributor suggested the problem was the Fuel Injector Pump Assembly (I think I have the name right but will check when I find the bill to confirm). They thought it had to be calibrated or replaced. I think the calibration has to be done at a regional service center.
We were enroute from Florida to the Chesapeake when we decided we had to try this.
We didn't want to take the week or two it would take to have it sent in to be checked and calibrated so we replaced it. (There were two available in the U.S. at the time.)
Since it was replaced, we have had absolutely no problem despite some pretty heavy usage on the ICW.
This unit is at the bottom starboard side of the engine, difficult to reach or see. The mechanic who did ours was a very experienced Yanmar mechanic but it took a full day to remove the old unit and install the new.
I will double check the name of the unit and re-post it if this one is wrong.
We tried everything possible for several years, found no help, and got into some pretty hairy (scary) situations along the way. Also, if this had been correctly diagnosed when the problem started, it would probably have still been under warranty.
Good Luck.
 
Sep 20, 2006
155
Hunter 49 Mystic CT
Thanks johnhen. I'm still having the problem. Restarting however is not one of them. Boat is getting hauled for the winter so I'll take it back up in the spring. I've spoken to a couple of yanmar mechanics and they didn't have any solid answers without seeing it themselves.
 
Jun 1, 2009
1,363
Hunter 49 toronto
Thanks johnhen. I'm still having the problem. Restarting however is not one of them. Boat is getting hauled for the winter so I'll take it back up in the spring. I've spoken to a couple of yanmar mechanics and they didn't have any solid answers without seeing it themselves.
 
Jun 1, 2009
1,363
Hunter 49 toronto
Here is a thought.
You might install a small electric fuel pump at the tank. This will assist the Yanmar pump which might be having problems drawing fuel from the tank.
 
Sep 20, 2006
155
Hunter 49 Mystic CT
No not yet. We boosted the idle speed to 825 and that seemed to help but no solid solution yet
The engine always starts right back up which is why I don't think its the fuel pump (yet). My next project is to pull the Variprop off and take it to the service center which fortunately is only a 45 min drive for me.
You see I'm a dope in that I didn't know I had to grease the prop each year. I went 4 seasons without doing it and I'm wondering if damage was done to the gears. If it's not switching from forward to reverse properly then 4 big blades pushing all that water could be causing the stalling.
 
Last edited:
Feb 21, 2009
4
2 49 Waukegan, IL
I wasn't referring to the fuel pump but the injector pump assembly. Even though your engine restarts easily (mine did too sometimes but not always if it had been running 6 or 8 hours) I think that is something that you really should be look into. The Yanmar distributor tech people may be good ones to talk to. The Mack Boring Co. is or was the Yanmar distributor for many of the Northeast and Midwest states. The distributor for Florida is located in Bradenton. They got my replacement injector assembly but I can't remember the name offhand. Both companies were really helpful to us.
I think they can usually service and re calibrate the assembly at their regional service centers.
Do you keep your boat in Florida? We moved ours there in 2012 and are near you on Longboat Key.
Good Luck.
 
Sep 20, 2006
155
Hunter 49 Mystic CT
Good advice. I'll check into that.
No the boat is in CT. We are considering moving the boat to Long Boat Key club and resort. Actually went there and spoke to the marina. While there I did see an H49 in one of the slips is that yours?
 
Sep 20, 2006
155
Hunter 49 Mystic CT
Well John you were right. The injectors and the and the fuel pump assembly were pulled and rebuilt. The word I got was The pressures were off on the injectors. Opening too high due to a slight lag on the fuel pump. According to the mechanic after reinstalling, the engine in now running to "spec". He tested it and it no longer stalls. I won't breath easy until I test it out next season. (I'm back in Florida now)

As an aside, once they figured out my boat they had two others that that exhibited the same problem with that engine but now they know what to look for.
 

MitchM

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Jan 20, 2005
960
Nauticat 321 pilothouse 32 Erie PA
how many hours were on the engine when it first started to show these symptoms ?