L3940 fuel sender replacement

PHILIP8N · Jul 5, 2016

My 2009 L3940 with 250 hours was beginning to have odd fuel level readings, reading fuel level that was less than actual tank level. Bar graph would go up and down between 1/4 and 1/2, or fuel light would come on at any given time. Even with tank completely full, I would never get a reading above 1/2. Okay, ready to replace fuel sender. The old fuel sender part number was TD060-31201. The new fuel sender part number is TD060-31202, price was $90 from Messicks. The hardest part of the job was trying to figure out how I was going to remove fuel sender as it sits at the very back of the firewall/bulkhead. My initial thought was to call my brother and remove hood. Fortunately, you can remove hood closure rod and prop assembly, and hold hood open with a 62 inch long 2x4 that will allow access to the fuel sender. Once old fuel sender was removed, I can see that rust has taken its toll. Most likely from me hardly ever keeping tank full, as I like to run out in the fall ready to add winter #1 fuel, and as I like to run out in the spring ready to add summer #2 fuel, white bottle Power Service year around. New fuel sender along with a new fuel filter was installed, as well as performing 250 hour service. Just wanted to share in case anyone else ever has this problem, the 2x4 hood prop is the way to go. Philip.

The Fred · Jul 5, 2016

Yes we rarely see any rust like that in a Diesel tank.

Not that it helps you but I have never used #1 Diesel in mine, just straight #2 with Power Service added at time of fuel delivery. My fuel tank is 330Gallon outdoors that also heats my shop all Winter.

Have never had an issue even at the extremes we get here (-30f).

Nice write up thanks! Fred

KenB2920 · Jul 5, 2016

I know hey are the same, but I swear the new one looks bigger than the old one in the photo.

Good post. Hope I don't need it but I'm saving it.

I completely removed the hood on my 3540 but I know that one was shorter than my now 5240.

okiecraig · Jan 30, 2025

PHILIP8N said:
My 2009 L3940 with 250 hours was beginning to have odd fuel level readings, reading fuel level that was less than actual tank level. Bar graph would go up and down between 1/4 and 1/2, or fuel light would come on at any given time. Even with tank completely full, I would never get a reading above 1/2. Okay, ready to replace fuel sender. The old fuel sender part number was TD060-31201. The new fuel sender part number is TD060-31202, price was $90 from Messicks. The hardest part of the job was trying to figure out how I was going to remove fuel sender as it sits at the very back of the firewall/bulkhead. My initial thought was to call my brother and remove hood. Fortunately, you can remove hood closure rod and prop assembly, and hold hood open with a 62 inch long 2x4 that will allow access to the fuel sender. Once old fuel sender was removed, I can see that rust has taken its toll. Most likely from me hardly ever keeping tank full, as I like to run out in the fall ready to add winter #1 fuel, and as I like to run out in the spring ready to add summer #2 fuel, white bottle Power Service year around. New fuel sender along with a new fuel filter was installed, as well as performing 250 hour service. Just wanted to share in case anyone else ever has this problem, the 2x4 hood prop is the way to go. Philip.

I know this is 9 yrs old, but glad to see it to use as a guide for doing the same job on my l3940. Only the price for the part is now $136!

TMGT · Jan 30, 2025

I'm about to do the same, $136! Darn

rScotty · Jan 30, 2025

okiecraig said:
I know this is 9 yrs old, but glad to see it to use as a guide for doing the same job on my l3940. Only the price for the part is now $136!

I'm going to save that OP writeup in case I ever have to do that job. But the corrosion bothers me. Is that much water that common in fuel? I thought fuel was oily enough to prevent rust.
I buy our fuel at a high volume gas station because I'm betting that passenger car diesel fuel is better.....but it's a bet based on ignorance.

Just as an aside, the US Bureau of Labor Statistics - they are the ones who track inflation - anyway, BLS has a great site, easy to navigate and even has classroom tools.
Using the inflation calculator on their website, $90 from when the original post was written would be $118.04 today with inflation. So whoever is charging 136.00 is just adding to the problem.

Still, I'm thinking either price seems reasonable for that part brand new. It would probably cost any of us about a quarter of that to rebuild the old one.