Yanmmar 4JH4-HTE 80HP 2007

[capitansurfista]

Hi, have a weird problem with this engine since it was installed new!..It stalls or almost does when hot and in low rpm shifting gears fwd or rvse. OK when cold...We have check diesel , filters, everything...anybody out there whom may know about this problem? Appreciate the help. We are in Ecuador. Thank you so much for any good ideas to try fix this problem.

[TheOffice]

Do you have the correct transmission fluid/oil?

[capitansurfista]

Originally Posted by TheOffice

Do you have the correct transmission fluid/oil?

Thank you so much for your reply and help..

I think so, SAE HD 30 its what Yanmar tech says we should use...
Engine has only 300 hours have been use very little by way. We are getting ready to take this boat an Irwin 52 to Panama in few months.

I had a suggestion on another forum about it like this:
" Re: Yanmar 3GM30. Engine stalls when warm but not when cold.
I would suspect a vapor lock in the fuel system.
Disconnect the fuel return and run the engine and let the return go into a cannister.
If return disappears or bubbles occur, change filters, check fuel pick-up in tank.
If that does not help, a new feed pump might be needed.
The return is needed both for lubrication and cooling of the injectors. If to little return, it starts vaporizing and problems like you describe happens."..

And we will try that soon next week and see ehat happens. But, why would transmision fluid cause this? I also thought about it and checked oil and its all fine...as well no smoke on exhaust...
RPM after warming engine starts to vary coming up or down a bit some RPMs anytime but not that often just ocasionally...thats another symptom of all these so I think it has to be fuel lines filters etc contous flow which is blocked by a debri somewhere....

Thank again for your time and help...

[Paul L]

Have you independently checked the idle RPM?

[Reefmagnet]

Left field suggestion. Is it possible the governor is not functioning correctly at times?

[capitansurfista]

I wouldnt go there now. Like to start by simple things...like rechecking all fuel lines, return line manifold, tank etc and doing what this guy of other forum suggested. I think it seems like bad fuel...so I am looking for another view in that line of things...The owner and last crew say they ve done all this but I will try to find out fuel system flows etc...Thank you for your reply.

[capitansurfista]

Yes, idle is OK 800 rpm shifting gears alright no sounds etc...starting engine all fine starts at once. Everything starts to happen after warming up...Got to go through everything about installation levels of tank and fuel pump to engine filter etc according to manual...and so on...thanks for your suggestion and time

[Paul L]

Originally Posted by capitansurfista

Yes, idle is OK 800 rpm shifting gears alright no sounds etc...starting engine all fine starts at once. Everything starts to happen after warming up...Got to go through everything about installation levels of tank and fuel pump to engine filter etc according to manual...and so on...thanks for your suggestion and time

Are you using the engine tach to determine th
e 800rpm or have you checked it externally? The engine tach might be off.
Do things get any better if you go to 825rpm?

[skipperpete]

Originally Posted by capitansurfista

Yes, idle is OK 800 rpm shifting gears alright no sounds etc...starting engine all fine starts at once. Everything starts to happen after warming up...Got to go through everything about installation levels of tank and fuel pump to engine filter etc according to manual...and so on...thanks for your suggestion and time

On your 4JH4-HTE there is a thermally operated coldstart device on the side of the injector pump with 2 hoses that allow coolant flow to the coldstart. When the engine reaches near operating temp the wax element expands and changes the injection timing. It would be useful to establish whether or not the mechanism is operating by checking it in the cold position and then again after the engine warms up. It’s the only thing I can think of that connects your engine problem directly to jacket water temp and it’s easy to view the lever and spring without any tools other than a flashlight and mirror.
Pete.

[skipperpete]

I agree that it’s very important to verify that the fuel supply is free of air, water,dirt particles and any problems caused by tank to engine fuel delivery AND return deficiencies.

[capitansurfista]

Originally Posted by skipperpete

On your 4JH4-HTE there is a thermally operated coldstart device on the side of the injector pump with 2 hoses that allow coolant flow to the coldstart. When the engine reaches near operating temp the wax element expands and changes the injection timing. It would be useful to establish whether or not the mechanism is operating by checking it in the cold position and then again after the engine warms up. It’s the only thing I can think of that connects your engine problem directly to jacket water temp and it’s easy to view the lever and spring without any tools other than a flashlight and mirror.
Pete.

Thank you Skipperpete. Thats new for me as I work usually with other engines smaller etc. But please could you specify what is that I should check on this thermal device to happen. How wouild I know when is working or not properly?..What should I be looking for when Engine warms up? etc...Thank you again for your help and time.

[capitansurfista]

Originally Posted by Paul L

Are you using the engine tach to determine th
e 800rpm or have you checked it externally? The engine tach might be off.
Do things get any better if you go to 825rpm?

Paul I just checked with Tach which actually is off sometimes also not working poroperly really, but only when it starts cold then goes off after few minutes...So we need to change Tach as well. But by sound I get from engine I dont think is too low or too high RPMs and by the shifting gears I feel engaging goes smooth. Everything seems to happen or does happens when engine warms up and at low RPMs. What we have been doing is engage forward or reverse when warm to avoid stalling (if we can) is get RPMs higher at same time that we engage Fwd or Rvs to dock but is pretty tricky its a %2 footer heavy...etc Thank you!

[Daziel]

Check out this post from another forum. Sounds like the same issue with same engine model and year. https://forums.sailboatowners.com/th.../#post-1333745

[Palarran]

I have the same engines (2) and one did that. I'd check your fuel lines, supply, return, and vent.

[capitansurfista]

Originally Posted by Daziel

Check out this post from another forum. Sounds like the same issue with same engine model and year. https://forums.sailboatowners.com/th.../#post-1333745

Thank you I got this from there and will check it out...
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.

Thank a lot Daziel I thought about it..it must be arund fuel inyectors and fuel pump problem related as our lines and fuel were checked manytimes and our gen runs from same fuuel tanks etc no problems there ever...