Fuel gauge calibration

[Cougsfan]

My fuel gauge stopped working completely a while back (It went to pointing straight up all the time, well past the 100% full mark, other times it read completely empty). After he had me check the ground and electrical connections, my dealer sent me a new sending unit under warranty. With the new sending unit the gauge now works most of the time (see below), but the reading is very pessimistic. When the tank is full it reads full, but when it reads 1/4 full, the tractor only takes about 3 gallons of diesel to fill it to the top. Other than bending the arm on the float for the sending unit, is there a way to calibrate the fuel level indicating system?

Also, the fuel gauge still sometimes goes to reading straight up (just every once in a while) and the tach starts reading what appears to be twice the actual rpm (again this just happens every once in a while, not very often). The tach and fuel gauge go weird in unison. Shutting the key off and turning it back on brings everything back to normal. I suspected a loose connection on the instrument panel electrical plug but have checked them all, and even put dielectric grease on all the connectors. The dealer is sending me a new instrument panel to attempt to solve this, but I am not confident that will fix it. Wondering if any of you have any insights?

By the way, I learned that the tach works by counting the ac pulses from the alternator. That is probably how most diesel modern tractors work, but I never knew that. Beats the heck out of the forever breaking tach cable on my old Ferguson.

 

[oosik]

I know that the fuel gauge on my Kubota M6040 is NOT super accurate. But it's, at least, consistent. I have an 18 gallon fuel tank. The needle reads half a tank. It will take 12 gallons to refill the tank. If the new panel doesn't fix the condition - get the dealer to send out a tech.

 

[LouNY]

A malfunctioning fuel gauge is a royal pain.
Other then getting a rheostat and wiring it in to simulate the various readings and then twisting, pulling, pushing on the harness it is hard to find the trouble on a fuel guage.
This link has a bit of information;
Universal Fuel Sender Questions and Troubleshooting

 

[Slowpoke Slim]

I don't have the same problem you're having Cougs. When my tank is full, the gauge reads full. When my gauge reads empty, the tank is empty. But between those 2 readings, the gauge is not linear. So when it reads 3/4 full, or 1/2 full, the tank actually has more fuel in it than the gauge reflects. Once it gets down to below 1/4, then it seems to get more accurate as it goes down.

Personally, I'd rather just have a sight glass in the side and be done with it.

 

[Hombre]

I don't have the same problem you're having Cougs. When my tank is full, the gauge reads full. When my gauge reads empty, the tank is empty. But between those 2 readings, the gauge is not linear. So when it reads 3/4 full, or 1/2 full, the tank actually has more fuel in it than the gauge reflects. Once it gets down to below 1/4, then it seems to get more accurate as it goes down.

Personally, I'd rather just have a sight glass in the side and be done with it.

I think that sight glass is a "better mousetrap" idea also. My gauge seems to work about the same as yours. If mine gets down around a 1/4 tank you "might" get 6 gallons in it. That's a 12 gallon tank. So that's not to bad, at least it's on the "high" side, my diesel pickup is further off than that....:laughing: Cougsfan, let us know what you find. My first thought would of been the same as yours, a bad ground. There is something I've heard about the Korean circuit boards is that the soldering on them isn't very good, this came from a tech that works on appliances so may not have anything to do with our application but who knows.

 

[ericm979]

My 3725's fuel gauge is calibrated like yours Hombre.

 

[scatterlandsfarms]

I've heard about the Korean circuit boards is that the soldering on them isn't very good, this came from a tech that works on appliances so may not have anything to do with our application but who knows.

A appliance repairman is a want to be tractor mechanic

 

[Mr Bitz]

No calibration. No adjustments. Maybe bending the float rod, but that's your call. Don't think Branson spends much $$ on fuel gauge systems.

 

[Hayloft]

Well fellas, sounds like my 3520 fuel level indicator has similar issues. When tank is full it will read full but as level goes down the indicated level drops, but not evenly. And no matter how low the actual fuel level is, the indicator won't drop much lower than half. Yeah I don't rely on the guage. I watch fuel level visually or with a small dowell dipstick and try to refill ole Nellie once she gets to half or so.
Would be nice to identify an aftermarket fuel guage that really works!

 

[Gafn]

Gents - I posted this in another thread but here it is again...
My gauge was acting just as you guys have described.

if your under warranty - get those fuel sending units/floats replaced.
My 2015, 3520H fuel sending unit went bad - heavy corrosion on the dang thing, clogging filters lines and the like.

I ran out of fuel once with this tractor, refilled the tank and it restarted without incident...
There should be a recall on how badly the sending unit/float was corroded...