L3800 HST/Engine issue I'm baffled

[KubotaMainer]

Hello All,

This is my first post to OTT but have found lots of helpful information here in the past. I am creating this post because I cannot find the answer to my problem and am hoping you can help. Here's the details. 2012 kubota l3800 HST with FEL and BH77 backhoe. 430 hours on the clock. Now the issue...

I was recently using the tractor and was driving up my driveway in mid range at about 2400 rpm when randomly the tractor RPMS spiked very high and was unresponsive to decreasing the throttle lever and was not responsive to turning the key off. After about 6-8 seconds the tractor died on its own. After a few seconds I restarted the tractor, it puffed a little white smoke but otherwise seemed fine. Went about my business no further issue. A few days later I am using the tractor in low range to move some dirt. Decide to switch to mid range and the tractor repeats the same issue above. After this occurance I put 10 hours or so on the tractor in both mid and low range with no issue. Then just yesterday I am using the tractor and need to travel up the road a few hundred feet so I put it in high Range and as soon as I press the HST pedal it revs wildly and is unresponsive to throttle or key shutdown. Eventually it dies but this time does not want to restart. It cranks over a turn or two and stops. Repeat 15 seconds later and it turns over hard 2 or 3 times. Wait a full minute and try and the tractor starts hard and is knocking loudly puffing lots of white smoke. After a few seconds it clears up and the tractor is fine. I don't dare use it in mid or high range and it has not acted up in the slightest in low range. Fluids are all at correct levels, I do not see any damage to the linkages underneath and I am baffled. What are your thoughts.

Thanks in advance!!

Kyle

 

[Jim L.]

Kyle

First thought is that this is a risky situation where the engine shows no response to a shutoff. For troubleshooting, you can have the hood (bonnet) up, air filter out, and something to jam into air intake to starve the engine of air (and not get sucked into engine).

Second thought is governor, injection pump, fuel camshaft, engine stop lever, stop solenoid, speed control plate, rod and nuts from accelerator?

I think that it would be best not to operate until this problem is solved because you can lose the engine.

 

[North Idaho Wolfman]

Your issue has Zero to do with the HST or the range.

The only things that can cause the issues that your explaining would be damage to either the fuel injectors or the Injection pump.

I'm leaning more towards some debris in the injection pump hanging up the rack.

 

[SidecarFlip]

Kyle

First thought is that this is a risky situation where the engine shows no response to a shutoff. For troubleshooting, you can have the hood (bonnet) up, air filter out, and something to jam into air intake to starve the engine of air (and not get sucked into engine).

Second thought is governor, injection pump, fuel camshaft, engine stop lever, stop solenoid, speed control plate, rod and nuts from accelerator?

I think that it would be best not to operate until this problem is solved because you can lose the engine.

Did that once with a 6-92 Detroit and a coat. Ate the coat....lol

 

[KubotaMainer]

Thank you for the replies! Based on your suggestions I did some searching and
Located a few posts of guys with similar year L3800a having issues with the fuel systems on these tractors. They were having a white smoke issue which I understand can mean incomplete combustion of fuel. Would it make
Sense to think that either the pump or injector is staying open causing too much fuel to enter the cylinder causing the uncontrollable engine rpms? Also after each time I restart the engine there is the white smoke almost as if the cylinder was overfilled with fuel. The most recent time it felt hydrolocked (hard time turning over).

Thanks again!
Kyle

 

[thepumpguysc]

The easiest thing to do is pull the injectors.. Have a look at the tips.
Handle them carefully.. u don't want to "mash" the end of it.. or clean it w/ a wire wheel.
See if there are any difference in the coloration of the tips.. THAT may give u an idea of which cylinder/injector is giving u trouble..
U CAN hook them back up outside of the engine & watch them squirt.. but be careful, u don't want the spray hitting u.. or its off the emergency room.

 

[North Idaho Wolfman]

Thank you for the replies! Based on your suggestions I did some searching and
Located a few posts of guys with similar year L3800a having issues with the fuel systems on these tractors. They were having a white smoke issue which I understand can mean incomplete combustion of fuel. Would it make
Sense to think that either the pump or injector is staying open causing too much fuel to enter the cylinder causing the uncontrollable engine rpms? Also after each time I restart the engine there is the white smoke almost as if the cylinder was overfilled with fuel. The most recent time it felt hydrolocked (hard time turning over).

Thanks again!
Kyle

If it hydro locked and you kept forcing it to turn over, you could have done some internal damage, bent rods and broken piston lands are what happens when they hydro lock.
Pull all the injectors, do as thepumpguysc, said and also do a compression test on each cylinder.