L3901 Fuel Sensor

Cherrybark

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L3901, Shredder, Grapple, Hydraulic Tree Shear, and the usual
Mar 15, 2019
6
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East Texas
L3901 died deep in the woods - naturally. Towed back to barn and discovered clogged fuel line from tank to water separator. Shot a bit of air up the line to temporarily clear the blockage. Cleaned water separator, put on a new fuel filter and successfully ran for a few minutes.

After a couple of hours on YouTube and in the forums, I expect to find a rusty fuel sensor unit has been dropping flakes, or maybe, chunks of rusty metal in the tanks. This seems to be an all-too-common problem. I considered removing the sender unit and, if it is a rusty mess, fabricating a cover and relying on the hour meter or a wooden dowel to keep track of fuel. But it's winter and I have time to clean the tank and install a new sensor. And I'll be much happier with everything working.

Two questions: Can someone provide the correct part number for the sender unit on an L3901? I haven't been able to find a drawing with part number in the Kubota "Service Parts Catalog".

Is there a fuel "proof" spray paint that can be used on the sensor unit to prevent this rust? Or does the risk of contaminating injectors make this a potentially dumb idea?

Once again, I promise myself to take the time to top of the tank and add stabilizer when parking the tractor. Though parts of that sender unit will always be above the fuel level.
 

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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curious and it's cold here....
from the cda website....l3901DT


No code has to be inserted here.
cost is $150 Cdn.
go online to Messicks, might be different part number 'south of the 49th' ? Also check which l3901

as for 'spray', see WHERE the rust is coming from. maybe the 'rod' ? where ever, clean with alcohol, then 2-3 coats of some 'diesel proof' coating. Maybe 'clear coat' or 'epoxy' ?? Use brush not spray, don't want to covet the sensor.
 

lugbolt

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ZG127S-54
Oct 15, 2015
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can't really paint it, at least not all of it.

Can't really use a dowel because of the way the tank is shaped and where the filler neck is.

Only option, make the sending unit out of stainless steel so it won't rust. Maybe some 308? But Kubota makes them out of cheap steel which will rust again, I did a ton of them back in the day, a lot of new on the lot tractors too. Not a particularly fun job either, but not terrible. Didn't pay squat and sometimes they didn't pay at all (Kubota/warranty) which was at that time par for the course.
 

North Idaho Wolfman

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I haven't heard of the L3901's having a fuel sending unit issues but there is a first to everything.
Yea no painting or coating it.

1737514293127.png
 

North Idaho Wolfman

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I did find a used one online and it looks like it might rust a little.

1737514516756.png
 

Cherrybark

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L3901, Shredder, Grapple, Hydraulic Tree Shear, and the usual
Mar 15, 2019
6
1
3
East Texas
Thank you all for the helpful advice. Before I get all worked up about defective parts, perhaps I should pull the tank, clean it, and maybe discover it's some other debris.

This is a screenshot of the fuel sending unit from a helpful YouTube video showing how to remove the fuel tank.


1737550859504.png
 
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GreensvilleJay

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Equipment
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
12,369
5,347
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Greensville,Ontario,Canada
YUCK !!!! That's ,well, GROSS.
Like the possible SS308 welding rod 'upgrade' ! Well, if under 14"(welding rod length ?)
Don't understand why it can't be painted, providing proper cleaning and fuelproof 'paint' is used.

If it's $150 up here, maybe $100 , south of the 49th, buy new one not worth installing a' rust proof' version
 

Cherrybark

New member

Equipment
L3901, Shredder, Grapple, Hydraulic Tree Shear, and the usual
Mar 15, 2019
6
1
3
East Texas
To conclude the Saga of the Suspicious Sender. Followed the "hood, steering wheel, and dash removal" portion of the above video. The hardest parts were removing the hood and trying to remember where my pully puller tool was. The steering wheel didn't come off with a couple of gentle taps.

The sending unit didn't look bad at all. The bit of brass brushing was probably unnecessary. A flashlight revealed some odd flake of material laying on the tank bottom near the fuel outlet. Fished out the mysterious trash with a bent coat hanger but couldn't figure out what it "had" been.

Put everything back together without having any unused parts. Always a relief.
 

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GreensvilleJay

Well-known member

Equipment
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
12,369
5,347
113
Greensville,Ontario,Canada
curious, so got this...
..there's a U shaped connector on the wire near #120. I'm assuming it's the GROUND for the fuel sensor.
It needs to be properly attached, otherwise the reading can be weird,wrong or none at all.
 

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Cherrybark

New member

Equipment
L3901, Shredder, Grapple, Hydraulic Tree Shear, and the usual
Mar 15, 2019
6
1
3
East Texas
I believe the float arm is attached to a variable resistor and that "U" wire provides an electrical ground to the sensor. Required since the tank is a plastic. Happily, my ground connection was more secure "ring" connector rather than that spade.
 

lugbolt

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Equipment
ZG127S-54
Oct 15, 2015
5,327
2,002
113
Mid, South, USA
the rusting issue can be caused by a couple things. One, leaving the tractor sit for a long time with just a little fuel in the tank in high moisture areas, and two when they ship the tractors over here from china or I mean japan, they are subject to salt in the air (saltwater) which can corrode the bare metal surfaces. That is one reason the entire transmission and engine are painted as an assembly.

I wish they'd coat the metal with, something, to keep em from rusting but it adds a little bit more cost to the sending unit which is paid for by the end purchaser. So they keep pumping them out as-is and deal with it on the back end (warranty) as needed and/or let the customer eat the cost after it's out of warranty. It was a known issue and honestly it wasn't "that" common, although I did my fair share of the sender replacements for sure. 3301, 3901, 4701, lots of 3301's.
 
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