Diesel tractor over revving, why?

[Perry Holbrook]

I've got a 23 HP diesel Kioti tractor, 3 years old. As I was operating the backhoe at about 1/2 throttle, the engine suddenly over revved, smoked for less than 10 seconds and then died. I checked all fluids, temps, etc looked over the engine for any obvious problem and all was fine. To my surprise, it started right up and ran fine for the rest of the job.
The next time I used it, it happened again, this time when I was trying to make it happen by operating the throttle from idle to fast and back a few times in rapid movements.

The only thing that was a little different is I had filled the fuel tank that was near empty with fuel that had been in the fuel can over the winter.

Can anybody tell we what could be happening and what my next step should be?

Thanks.

[Tom M King]

I know nothing of that tractor but if it has not a tremendous amount of hours on it and a mechanical fuel pump, I would change the fuel pump. After checking the air intake to see if it's contaminated, I would change the mechanical fuel pump. It sounds like it's getting too much fuel for some reason. Might have been flooding out when it smoked and died.

[Bill Dufour]

First easy step, did any water come out of the filter drain. Drain the fuel tank and let any water settle out before pouring it back in.
Bill D

[Tom M King]

I’m interested to hear about the water. None of my tractors will let any water get past the filter. Too much water and they won’t start or would quit running.

[Tom M King]

How many hours on it?

[Jim Koepke]

Are you sure there wasn't any fuel contamination of any kind?

jtk

[Michael Schuch]

Since the RPM of a Diesel engine is only controlled by how much fuel it gets if the Diesel engine is overrevving either the fuel injection pump is sending too much fuel OR the engine is burning something else as fuel... i.e. engine oil.

Water in the fuel could cause the engine to cut out but it shouldn't cause the engine to overrev.

The engine probably has some sort of governor that cuts the fuel when the engine overrevs causing it to die... so the engine doesn't run away uncontrolled. I would guess the base cause of the engine cutting out is the overrevving.

I would suggest trying a forum that has more expertise on Diesel tractor engines than a woodworking forum. https://www.tractorbynet.com/

[Perry Holbrook]

How many hours on it?

The tractor has 250 hours

[Perry Holbrook]

Are you sure there wasn't any fuel contamination of any kind?

jtk

I'm guessing it is somehow related to the fuel. Don't understand how water would made the engine rev up. I looked at a diesel fuel conditioner at the auto parts store yesterday but thought it might be better to drain tank. But before doing that, I wanted to ask those smarter than me if I was on the right track. As far as going to another forum, I have great respect for members on this forum and know that someone will have the answer to most of lifes problems.

[Tom M King]

That’s still a new one. I’ve put over 3,000 hours on my utility tractor myself. The hour meter was broken when I bought it when it was 12 years old 33 years ago.

No question it’s a fuel issue.

[Ronald Blue]

I do believe it's a fuel issue. Not exclusively water though but with it happening right after adding fuel it most likely is. Does it have a fuel/water separator? If there is a drain where you can access and drain some fuel off, if there is water in the fuel it will come out first. So only drain a couple gallon if it's a valve you can close in to a clean container. The water will be easy to see if it's there. Get a new fuel filter as well. Whether you choose to drain all the fuel will be up to you but unless it's a large tank I probably would. You can still use it to start brush piles on fire etc. But it doesn't take much water to create issues. The surging and smoking are definitely a contaminated fuel symptom.

[Tom M King]

I've never seen a tractor fuel tank that didn't have a draincock at the bottom of the tank. You have to get under it, but even on the old ones it's pretty easy to operate. You can drain some out in a glass jar, and it's easy to see water in it. I've never seen a diesel that didn't have good enough filters on it to keep all the water out of the injectors though. At 250 hours, the fuel filter should not be a problem. I don't see any way this is a water issue, but don't claim to never be wrong.

I would check for oil in the intake before I would worry about it being a water issue.

Does it have both a lift pump and an injector pump? The "lift" pump is usually a mechanical pump. That's what I would put the priority on checking after a quick look over the linkage system to the injector pump.

[Maurice Mcmurry]

My little diesel Ford has a hand throttle and a foot throttle. Several times I have run over a stick or sapling that got stuck in the foot throttle linkage which has caused an unexpected rev. It does not smoke or die. It is alarming. I did a google search "2021 23 HP diesel Kioti tractor over rev smoking dying" The majority of the results are about bad fuel.

[Jim Becker]

When that's happened with my Kubota BX22 over the years (same HP engine) it's generally been in the fuel system...debris or bad fuel. Clean/change the filters and you may need to deal with debris in the tank at the outlet which can be a super pain in many tractors.

[Jim Becker]

I've never seen a tractor fuel tank that didn't have a draincock at the bottom of the tank.

Alas, that's not a thing with many subcompacts that utilize blow molded tanks that are complexly shaped and generally live under the seat, draping over the drivetrain.