JD 3020 gas gauge issue

[Jefd]

Hi all!
My 3020 gas gauge is not operating correctly. On startup, it seems to read ok'ish. Once the tractor runs for awhile, the gauge pegs out at the full mark. I have replaced the sending unit and still have the same issue. I switched from a generator to an alternator a few years ago. Do I need to have some resistance on the gauge line or are the JD sending units that junky?

 

[Geo-TH,In]

Many on here will tell you I'm no expert on anything. So my opinion is worth every penny you are paying me. LOL
Most gas gauges are an ammeter and the sending unit is a variable resistor attached to some kind of a float.

A full tank the float is the highest and the variable has little resistance and ammeter fuel gauge, shows max current, Full.
If the sending unit is good, then too much current may indicate you have a higher than normal voltage from the alternator.
If the ammeter is bouncing all over the place, you may have a bad sending unit or a bad connection.
Sometimes the tank is connected to ground.
My opinion is worth every penny you are paying me.

Do diesels have a gas gauge or a fuel gauge?
If Polarity is an issue, the fuel gauge should be backwards

 

[Fixingfarmer]

The Deere ones are generally though of as very high quality and very expensive. I wonder if your problem is closer to the gauge itself. Was it negative ground before the alternator switch?

The gauge will need to match the polarity I believe the sender won’t care the sender is much more expensive and not usually solving my 4020 3010 issues. You also will need to add a ground wire at the new gauge I usually go to the support bracket with a 3/8 bolt through an eyelet. Instructions will come with the John Deere gauge. Don’t skimp on the gauge consider what you already spent as a learning experience and use my struggles of trying 3 aftermarket gauges on one tractor before the oem update one working.

 

[John T]

To your question: I switched from a generator to an alternator a few years ago. Do I need to have some resistance on the gauge line

Converting from a generator to alternator, provided alls wired correct and working properly, should NOT require any additional resistance in the gauge line. I DO NOT think the conversion is the cause of your problem.

Far as I know even New Generation that used Generators were still POS Ground, however most alternators are for NEG Ground SO THERE MAY BE PROBLEMS !!!!!!!!!!!!!!!!!!!!!!! NOT due to any slight different charging voltage, BUT TO POLARITY ISSUES ?? I dont think the sending units variable resistance is polarity sensitive, while the gauge itself may be, not sure.

Did the gauge issue occur when you converted to alternator ??????????? Was it the same with Generator orrrrrrrrrr Alternator ???????????

In the case polarity is NOT the issue ?? I have often seen poor or resistive tank or sending unit grounds or connections be the cause of such problems. The sender needs a good ground regardless if direct wired orrrrrrrrrrr it relies on the tank itself being grounded. Since the sending unit was replaced Id take a look to insure the sender (direct or via a good tank ground) is well grounded and check all the wiring and grounding connections.

John T

 

[Jefd]

Thank you all for the help. The tractor was a positive ground before the switch to an alternator. The alternator has a built in regulator, so I'm wanting to know what voltage I should be reading. Should it be around the 14 volt mark? Also, I will try a new gauge and make sure it's grounded. I only have 1 wire going to my tank for the sending unit. How can I ensure the tank is grounded? All help is appreciated! Thanks again, Jeff

 

[John T]

Assuming the alternator is NEG Ground there may be some reverse polarity issues when you converted, but I'm not going into all that for now. Thats a whole other thread.

Subject to RPM, Alternator, and Battery condition, I'd expect in the neighborhood of around 14 charging volts on the battery as you indicated at RPM, but I don't think that's (slight voltage difference) the cause of your gauge problems.

If there's ONLY ONE wire to the sending unit, I suspect that's to the senders variable resistor (which wires to gauge) and it gets its ground by being mounted to the metal tank which of course needs a good case/frame ground itself. I have ran a jumper wire with a good bond from the metal sending units case to the grounded battery post to insure a good case/frame ground connection in case the tank isn't well grounded. TRY THAT FIRST. Use an ohm meter to see if theres a good no/low resistance from the tanks clean metal to the grounded battery post. If not, try the grounding jumper wire

Again I don't think polarity of the senders variable resistance is an issue HOWEVER polarity of the gauge MAY OR MAY NOT BE A PROBLEM I JUST DONT KNOW.

Try to run a wire from the senders metal case to the grounded battery post see what happens ........... Whether or not the gauge is polarity sensitive I cant say................when you switched from POS to NEG ground the coil polarity needed changed, any ammeter leads need swapped

Hopefully some New Gen Fuel gage and polarity experts can help out Im more of a Two Banger guy sorry I cant help more

John T

 

[Fixingfarmer]

Polarity of the gauge has to be correct. the sender will not care.
I think Your new sender probably has a ground terminal as well that can go to chassis if you feel like it or disregard it’s not a problem as long as you haven’t switched to a poly tank that’s what the new post is for to ground the sensor in a plastic tank. One could also just use one of the screws but I think they do include that as a reminder to run the wire if you are doing that fuel tank replacement. As John t said the tank on yours should be grounded.

 

[John T]

Polarity of the gauge has to be correct. the sender will not care.
I think Your new sender probably has a ground terminal as well that can go to chassis if you feel like it or disregard it’s not a problem as long as you haven’t switched to a poly tank that’s what the new post is for to ground the sensor in a plastic tank. One could also just use one of the screws but I think they do include that as a reminder to run the wire if you are doing that fuel tank replacement. As John t said the tank on yours should be grounded.

Thanks for the info Farmer. Good to hear gauge polarity DOES MATTER I wasn't sure. FWIW Im in your camp polarity on the variable sender resistor does NOT matter.

John T

 

[wore out]

Thanks for the info Farmer. Good to hear gauge polarity DOES MATTER I wasn't sure. FWIW Im in your camp polarity on the variable sender resistor does NOT matter.

John T

The info above will help with troubleshooting the system as it left the factory, but doesn't get into the ramifications of a ground polarity swap.

DEERE GURU Tim S has part numbers for a matching gauge and sender when changing to (-) ground, I would give a shout out to him on the DEERE-specific Board if there are unresolved questions here.

I understand Jerry Trcka at Evergreen Restorations is knowledgeable about the polarity swap issue, as well.

 

[tim s]

Yes you need a negative ground gauge,, the senders are the same but they are normally worn out from bouncing around for years.Jerry Trcka is where you need to get the gauge/sender set.. I keep a couple sets on hand here,, customers are always happy to have the fuel gauge working..
Jerrys number is 715-635-8629

 

[Jefd]

Thanks all! I really appreciate your willingness to share your knowledge and expertise! I'll call Jerry!

 

[tim s]

To any one working with this issue the Deere replacement fuel gauge is about 3/4" bigger and fits like socks on a Rooster,,you need to bent the hold down clamp to make it "sorta" fit,, the gauge from Jerry is the exact fit and works out nicely

 

[Jefd]

I just talked with him, new gauge and sender coming my way!

 

[Fixingfarmer]

To any one working with this issue the Deere replacement fuel gauge is about 3/4" bigger and fits like socks on a Rooster,,you need to bent the hold down clamp to make it "sorta" fit,, the gauge from Jerry is the exact fit and works out nicely

I will admit that Jerry’s gauges are NOT what I had used as far aftermarket gauges THAT DO NOT WORK. Everything Ive heard about his stuff is great and it’s certainly priced comparative to Deere who does have the fitting issues. I’ve just gone to cutting off 2 legs of the bracket and depending on how the screws come out anyway getting a bit more creative with how to hold the gauge in place.

It’s too bad OTHERS can’t stock some decent ones. Perhaps working with someone like Jerry…you have a fantastic point Tim s about stocking some ahead of time that’s been my only issue as the green ones are in town.

 

[Jefd]

Ok, here’s the solution. Thanks to all who helped! I contacted Jerry at Evergreen. Got a new fuel gauge and sending unit. Wired according to instructions, now works as it should. Again, thanks to all.
Jeff

 

[miangus]

To your question: I switched from a generator to an alternator a few years ago. Do I need to have some resistance on the gauge line

Converting from a generator to alternator, provided alls wired correct and working properly, should NOT require any additional resistance in the gauge line. I DO NOT think the conversion is the cause of your problem.

Far as I know even New Generation that used Generators were still POS Ground, however most alternators are for NEG Ground SO THERE MAY BE PROBLEMS !!!!!!!!!!!!!!!!!!!!!!! NOT due to any slight different charging voltage, BUT TO POLARITY ISSUES ?? I dont think the sending units variable resistance is polarity sensitive, while the gauge itself may be, not sure.

Did the gauge issue occur when you converted to alternator ??????????? Was it the same with Generator orrrrrrrrrr Alternator ???????????

In the case polarity is NOT the issue ?? I have often seen poor or resistive tank or sending unit grounds or connections be the cause of such problems. The sender needs a good ground regardless if direct wired orrrrrrrrrrr it relies on the tank itself being grounded. Since the sending unit was replaced Id take a look to insure the sender (direct or via a good tank ground) is well grounded and check all the wiring and grounding connections.

John T

Depends on the age of the tractor. On my 1965 4020 when I switched to an alternator and went from positive ground to negative ground, I had to get a late model fuel gauge. An early diesel converted to 12-volt negative ground will also need a gauge from a late model. Later models that came with alternators have the correct gauge.