Governer problem M25 /Kubota D950

[pullark]

Hello All,
I have a problem with my engine after running it for extended period ,say 3 or 4 hrs. What happens is engine starts and runs fine but when I throttle off (after motoring for some time)to go into neutral the engine stalls. This is not good when going into a marina or catching a mooring.What adds to the drama is I cannot restart the engine as starter motor really labours as happens with a discharged battery. Alternator is fine and battery shows 13.4 V ...starts engine from cold just fine. It's as if the injector pump is in the fully shut position and possibly this makes it difficult to turn the engine over? Or is this an unrelated issue like a bad earth? The engine is definitely a D950 Kubota but not a Universal M25 XP. I have one of those in my Catalina 30. I suspect it is either a tractor engine or generator engine that has been marinised. The throttle/governer control is basic compared to Universal . Any thoughts on what I'm experiencing? The engine is otherwise in good conditon.
Thanks
Kevin

 

[weekendrken]

Hey Kevin

Diesels don’t use “earth” - there’s nothing electrical when they’re running, only for starting.
A governor is a high speed regulation not idle.
I don’t mean this any way other than FYI, but the apparent breaknowledge about diesels might indicate you could benefit from a professional looking at her.
Have you checked for normal idle RPM setting? Specs are on the IC30A forum.
A weak lift pump? but it would seem that would show at cruising rpm as well.
Dirty injectors? but again I think you’d gave indications at other RPM.
I’d suggest you cross post your Q? on the IC30A forum for wider input.
Do you have pix of your mongrel engine?

 

[Stu Jackson]

Could be fuel: Fuel Starvation and The Obscure Ball Check Valve

Confusing what your title says (M25/D950) and what you say about it NOT being an M25XP. The M25 IS a D850, the XP is the D950.

What adds to the drama is I cannot restart the engine as starter motor really labours as happens with a discharged battery.

Could be the wiring to the starter solenoid, there is a fuse and holder cleverly hidden beneath the alternator. I've pulled my OEM one out and relocated it.
Good luck.

PS - Ken is right about the C30 website. The C34 and C36 skippers have the same engines and also have tons of resources for you (www.c34.org and www.c36ia.org)

 

[weekendrken]

Kevin
I mis read your description about starting. If that was due to a poor ground I’d think it wouldn’t make a difference whether it was cold or run 2-3 hours.
The real question is not what the battery V is - what’s the V at the solenoid B post while cranking and the S terminal as well.
Do you have the OEM btty cables?
Sometimes a battery V can be UP but there’s no capacity to provide cranking amps. More diagnosis is needed to help you.
Can you post a vid of the starting problem
The IC30A forum wiki has an article about issues with the S circuit to the solenoid (and includes what Stu mentioned.)

 

[Hayden Watson]

FYI all Universal diesels are marinized Kubota engines. As Stu said, M25 = D850, M25XP = D950. This is really helpful when buying engine parts.

 

[weekendrken]

FYI all Universal diesels are marinized Kubota engines.

True, but not all marinized Kubota engines are M-25s or M-25XPs. As Kevin indicated, there are boat engines that are a mongrel -- i.e., a KB engine that did not come from Universal Medalist, but was instead put together from salvage "parts."

We have a C-30 owner who salvaged a Kb D640 engine and assembled his own "M3-20" (more correctly an "M3-20 - like") engine.

He's in the PNW and on the International Catalina 30 Assiciation site.

 

[pullark]

Thanks for your input guys. I realise that the engine doesn't need any electrical input when running (except for electric fuel pump if fitted). The engine is a D950 with number stamped on the block near injector pump. I am trying to establish if I have two related or separate issues. Issue #1 engine stalls when I go to shift to neutral after extended running (have an Ultraflex dual action engine/gearbox control by the way....start-in-gear lockout system not fitted). Issue #2 cannot restart because starter motor struggles to turn engine over despite plenty of juice in battery.
My hunch re issue #1 is that there's something not quite right with throttle/governer set -up and possibly its performance changes when conditions alter such as springs in mechanism losing tension with hot engine? Maybe a faulty throttle mechanism shuts off rack in injector pump so no fuel supplied to injectors? Would this cause engine to be hard to turn over on attempted restart? I would think not....engine should still spin over but just won't fire up. Do you agree?
I may have a separate and discrete issue with the starter circuit re difficulty with hot starting....issue #2 I did notice that the wire from battery switch to starter motor had a couple of gouges in it where something had chaffed or ground it in the past. This was mainly damage to the insulation rather than the wire , however I did notice the exposed wire was oily. Damaged sections were covered by insulation tape so no chance of shorting. Maybe the compromised insulation and oily wire causes massive voltage drop when the engine is hot? I have replaced this cable and engine starts (from cold) instantly as before. The real test will be what happens when I attempt to restart the motor after extended running. The suggestion about faulty solenoid or start switch wire is a good one...I will test these to see if I'm getting full voltage at the switch and solenoid. Again,is heat somehow causing an open circuit?
I take on board the suggestion about engaging a diesel mechanic. However the challenge is for the mechanic to be present when the problems actually happen. Not easy to replicate from cold start. I have spoken to a couple of diesel guys about this . One said he had little practical experience with governers in older engines and the other said diesels just need clean air and fuel to run . This was no great revelation to me and it's a true statement....but basically he was saying ..I don't want to know....too hard.
This engine is indeed a mongrel but I will get on top of it. I know from many years experience with my M25XP in the Catalina that the Kubota D950 is a great little engine. Will let you know progress as I work to solution. Thanks again.

 

[msmalter]

Your problem sounds very similar to the problem my sister-in-law had on her Beneteau 49, so I have been through the thought process already. It turned out to be an injector problem, but that doesn't mean yours has the same problem. Start with the simple and inexpensive things, then move to the more complex. Also, begin with the assumption that the stalling and the inability to restart is the same problem until you have reason to believe otherwise. The cheapest/easiest thing to check is the fuel tank vent. If the vent is clogged, air can't get into the tank to replace the used diesel, and the tank will be a vacuum that prevents flow of fuel. Next time the boat stalls, pop the fuel tank fill plug and then see if it restarts OK. When the engine is running, I believe the only electrical requirement is the electric fuel pump. When the engine stalls, can you still hear the ticking of the fuel pump? I don't know why the pump would fail to deliver a low volume of fuel when it is able to deliver enough fuel at high RPM. If the fuel pump is working correctly, then the stalling has to be related to fuel delivery to the cylinders. I would change both fuel filters. Probably not the cause, but inexpensive and needs to be done occasionally anyway. Diesels are stopped by cutting off fuel supply. Do you have a cable activated shut off (pull the cable handle) or an electric shutoff (turn off the key)? If electric, perhaps it is malfunctioning when it gets hot, causing both the stalling and failure to restart. You say that it usually stalls after 3-4 hours of running. If you purposefully shut the engine down after 1 hour, will it restart? If it doesn't, then the failure mode exists before the engine stalls. Not sure what that means, but probably good to know. I think the only things left are the high pressure pump and the injectors. I am not a mechanic and can't help diagnose those. Good luck!

 

[Hayden Watson]

Have you tried using the compression release to get the engine spinning then drop it to fire the engine?

 

[weekendrken]

If you haven’t already, get or fabricate a push button remote start switch to make troubleshooting easier.
You can either clip it to the solenoid, or remove the S wire from it and use a 1/4” disconnect terminal on the remote switch. Or if you replace the AGM fuse holder with a blade type ATC you can plug the remote switch in there and also use that point for the S wire V test while cranking.