Funky fuel gauge--is yours like this?

[matts70]

It's been this way for years and I've always just accepted that's the way it is. Then I started wondering, "Is everybody's fuel gauge this funky?"

From a full stock tank, I can drive 75 miles before it hits the 3/4 mark, another 25 before it's at the 1/2 mark, and then it takes 20 miles before the bottom half passes by and it's on E. It works as long as you know to expect it, but is this a common Ford Bronco fuel gauge, or has mine been defective for 20 years?

Curiosity just got the best of me while I'm sitting here.

 

[bknbronco]

Is it on empty when the tank is empty and exactly on full when the tank is full?

You can take the guage out and adjust the pointer on the empty and the full marks.

 

[matts70]

When full, it's right of "F". When it's bone-dry, it's left of "E".

 

[rjrobin2002]

Ours sound a lot a like. Mine only goes to 3/4 tank when full and stays there a while and fall fast. When it hits "E" the tank is empty. I consider it good enough.

 

[zombie66]

Same here. Mine would always be above the F mark on full but when it hit the 1/4 mark that was mine on empty. Glad I had the auxillary tank to use while I figured that out.

 

[Muddy]

I have the issues. I alway just chalked it up to design of the sending unit.

 

[Scoop]

My guess is you need to adjust the pick up level of the sending unit in the tank. PO maybe installed a new sending unit and did not adjust it correctly?

 

[miikee73]

Same here. Mine would always be above the F mark on full but when it hit the 1/4 mark that was mine on empty. Glad I had the auxillary tank to use while I figured that out.

Mine was doing that also,with a little expermenting with an OHM meter,I pulled the sending unit out of the tank and bent the float arm. Works like a champ now. I've had several different cars that the gauge fell at different rates,I think it is a design flaw. You just don't calculate your distance according to how many miles you got on the first 1/2 tank.
At least the EB gauge is small,I drove a '71 GMC 4x4,for 18 yrs,the gauge had about 3+ inches of sweep,and I swear going down the hiway I could see it move.

 

[yakelys69]

I built a microcontroller to program my tank and gauge separately. It works and has been tested with with both the stock gauge & autometer gauge along with bc broncos aftermarket sending unit and should work with the stock sending unit. It took me over 6 months to get it correct and has worked seamlessly for 1 year now. If there is interest I can have some boards made and talk to the site admin about being a sponsor if needed.

 

[DirtDonk]

I think that's a great idea yakelys. Assuming that the wires are in decent shape, the other methods work too, and are "free" (sort of), but if someone can purchase a compensating device that's simple to wire in, not too big, and (most important for most EB owners) not too expensive, then that'd be a good way to go.
If we can simply hook something up without pulling tanks, pulling gauges, and fiddling with things repeatedly, I'd bet there would be a market.

I'm thinking that it would have to come in at below $25 to appeal to a large enough group to be worth your time. But if you can't make some money at it at that price, it's not worth your time anyway.
If you know how much you have into it, and how much you'd like out of it, with how much time you have to spend on it, then let us know how much you think it would cost (retail) for you to sell it.
Then let the comment segment start.

I'm assuming it goes between the switch and the gauge then? So that one unit would effect both tanks on dual tank models?
Then again, maybe it's more for a single tank application. If both the sending units are working differently and making the gauge read inconsistently, that would make your work-around a little less effective?

More info is good.

Paul

 

[Broncobowsher]

I built a microcontroller to program my tank and gauge separately. It works and has been tested with with both the stock gauge & autometer gauge along with bc broncos aftermarket sending unit and should work with the stock sending unit. It took me over 6 months to get it correct and has worked seamlessly for 1 year now. If there is interest I can have some boards made and talk to the site admin about being a sponsor if needed.

I could see it theoritically possible with an ATtiny.

Recently I have been playing with the Arduino. I am in the process of going a step further. Running a stepper motor based on sensor readings. The fun thing is the senders are not real liniar. The temp sensor I calibrated is fairly good mid range but the tails had opposing slopes. Takes a bit of creative programming. Other uses include auto ride height air suspension on the utility trailer (any load, same ride height and a soft ride for it as well).

As for mass production, this could get interesting. You are actually pulling 2 calibration sources (maybe 3) as you are trying to get a gauge that probably won't match other gauges to read a level sender (or two) that probably isn't matching other senders. There are a lot of curves that need to be calculated and matched up doing this. But I am sure you can really dial it in too.
I am guessing you are simply using a pull up resistor on the sending unit and reading voltage off that. PWMing the output signal? Did you delete the original IVR when doing so? Any issues with temperture compensation with the bimetalic springs in the gauges?

 

[yakelys69]

I made it for a 1 tank setup, but should be able to change it just a bit for a 2 tank setup. I will work on my costs this week and start its own thread next week. It has a similar function to a slosh module built in and allows for variances in gauges / senders I have two stock gauges that require different values for 1/4 1/2 & 3/4. Sorry matts70, I think this is the only way to get a non-linear gauge to work with a linear sending unit. All new senders seam to be linear from what I understand.

DirtDonk thanks for the reasonable reply.