Put old Diesel in the Tank, Kubota M4700

BotanyMechanic

New member

Equipment
Kubota RTV900, M4700
Sep 11, 2024
3
0
1
East Texas
I've just taken over a property, and there was a transfer tank there with Diesel in it, Kicking myself for not checking it first, I assumed it was fine and Wish I had assumed the opposite and just drained and replaced it. I went top off my M4700 from it and then got about 200 feet before the engine started knocking, and I think it was white smoke that was coming out? I don't recall clearly now.

I turned it off, and it has not started since. I siphoned the gas out of the tank (it looked like muddy water for a while at first), removed the fuel bowl and let that drain until it was a slow drip. Fuel filter was replaced, as the old one had a bunch of orange sludge on the paper. I then added 5 gallons of Fresh diesel (I know the capacity is much more though) with Power Service Bio Kleen and Power Service Clear Diesel. I filled bowl with the fresh treated diesel, and bled it as per the operators manual. It turns over, but It still did not start.

Is there anything else I can check or try? Another way to bleed it maybe? I have not purged the injector pumps. I'm going to try again to start it in the morning, hoping the additives just need a minute.
 

Flintknapper

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Premium Member

Equipment
L2350DT
May 3, 2022
1,783
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Deep East Texas
I would 're'-bleed the system and try again with a fully charged battery.

IF it doesn't start (or try to start), then you may be in for some expensive repairs.

Sounds like initially... the fuel system was subjected to some nasty water in the fuel.
 

Jsjac

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Equipment
B2650
Feb 13, 2022
178
250
63
New Hampshire
You said you drained the gas?? I hope you ment diesel fuel?
If it was actually gas that sounds expensive to me.
 

GreensvilleJay

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BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
Apr 2, 2019
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it's going to be expensive...
sigh..
Unless that transfer tank had a lock on all the openings, you should have drained it.
No telling what is in it.
When kids kept stealing my gas cans, I got fed up, dumped 2#s sugar in the new one.....
..can was stolen that night....
 
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Runs With Scissors

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Equipment
L2501 TLB , Grappel, Brush Hog, Box Blade, Ballast box, Forks, Tiller, PH digger
Jan 25, 2023
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I am trying to wrap my head around the "knocking" sound part.

I could understand it just running rough, but what would make it "knock" ?

If the fuel filter was clogged, wouldn't it just stumble and die, like it was ran out of fuel?

I think a thorough cleaning/inspection of the fuel system is in your future.

If that checks out, then I have 2 theories.

1. It was "basically" pure water in that container, which was put in, and when the injectors sprayed "pure water" into the cylinders they did not 'combust" and effectively 'hydro-locked" the motor.

2. There was gasoline (or some other similar fluid) in that container and that fluid "detonated" and caused similar damage to hydro-locking.



Edit: Maybe a compression test is in order? Just to save the time/money of a fuel system "rebuild" on an engine with a bent rod.
 

D2Cat

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L305DT, B7100HST, TG1860, TG1860D, L4240
Mar 27, 2014
13,886
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40 miles south of Kansas City
Your fuel filter should have stopped any crud from getting past there. Since you changed the filter and have clean fuel I would spend some time bleeding the fuel line to the injection pump, making sure that line has clear fuel. Then bleed the fuel lines at the injectors (just loosen the line nut a few turns at each injector). Have the throttle lever at maximum fuel, turn engine over for about 15 seconds, wait for 1/2 minute for starter to cool off. Repeat this process until there are no air bubbles at the injector nut. Be patient, this could take 5 or 6 procedures. You will probably see one line with no bubbles so tighten that line and continue for the remaining lines. When all lines a clear of air it should fire off. May run crappy for a minute or two then clear up.

You are fortunate to have an older fuel system without the modern "conveniences" of govt. regulations!
 
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