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Would You Buy A Fuel Level Sensor For ~GBP100 That Worked Reliably ?

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Discussion Starter · #1 · (Edited)
I've been thinking about creating a fuel level sensor that works reliably for almost as long as I've owned Nell. There's a few ways to do it, but all would involve a changeover unit, where the existing pump/sensor unit is replaced with one re-sensored and re-wired to suit. The new sensor would be run by a microprocessor, hence the need for internal re-wiring, and all of the electronics would need to be sealed against attack by petrol.
The existing float system would be replaced by a full length circuit board, and there may need to be different length boards for the three variants. (TBA)
Here's how it would read:-
Gauge segment
Tornado
(18 litres)
TNT
(16 litres)
TreK
(22litres)
816-1814.2-1619.6-22
714-1612.4-14.217.1-19.6
612-1410.7-12.414.7-17.1
510-128.9-10.712.2-14.7
48-107.1-8.99.8-12.2
36-85.3-7.17.3-9.8
24-63.6-5.34.9-7.3
1 + fuel light2-41.8-3.62.4-4.9
0 + fuel light0-20-1.80-2.4
It should be possible to make the fuel light flash and the segments alternate from all on to all off when the level gets below 1/9th.
The OEM cost is ~ GBP70, but this system is expected to be more expensive at ~ GBP100
 

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Sounds like a brilliant idea. I'm fed up with having a gauge that reads 6/8 full for 100 miles and then plummets to empty in the next 60. How easy (or difficult) would this be to fit and wire in?
 

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Discussion Starter · #4 ·
Sounds like a brilliant idea. I'm fed up with having a gauge that reads 6/8 full for 100 miles and then plummets to empty in the next 60. How easy (or difficult) would this be to fit and wire in?
Easy for you, hard for me.
All you have to do is remove the pump unit from the tank and install the replacement. The connections external to the tank are unchanged.
For me, I need to know what the fuel volume vs height relationship is for each tank. Easy for my Tornado, I can do that myself, but I don't have a TNT or a TreK, so I would need someone else to do this for me.
Then it's a case of measuring the fuel height and presenting a corresponding "resistance" to the gauge.
That's about the bones of it.
 

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Discussion Starter · #5 ·
I'm under whelmed :confused:
It seems that either very few Benelli owners care about how much fuel is in their tank, or maybe there's only a very few with crook sensors?
(I'll do it anyway, but it'll be on the back burner.)
 

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Just thinking most of the bikes I’ve owned had no fuel gages so looking in the tank is still a habit :).
At the moment my gage is working, I compared it to Wyn’s when we did a run together last year. Both gages gave slightly different readings for the same milage, mine giving lower readings than Wyn’s but not enough to worry about.
So not interested it’s just a convenience while riding to save doing mental arithmetic :D.

Dave
 

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When I finally find the right Tornado this is the sort of mod I would probably want to do.

It would drive me crazy on my other bikes as I use them for touring and commuting, but the Tornado will be a bit of a toy and only burn a few tanks of fuel a year.
 

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Discussion Starter · #8 ·
It would drive me crazy on my other bikes as I use them for touring ...
Exactly the reason I want to be able to trust my gauge. I want to know that when the last segment drops off, I've got 2 litres left ( > 1.5 & < 2.5 ), which should take me 1/8 of what I've already done. If I've done 280 km, I've got another 35 up my sleeve. Then I know if I'll make it to the intended fuel stop. That can be the difference between a 4 tank day and a 6 tank day.
When I'm on a mission, I don't want to spend it topping up.

Ideally, and eventually, I'll make an injector time counter. That'll give me instantaneous economy as well as average, and an estimate of the total distance on the current tank.
 

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I think an accurate gauge would be very useful, just not for £100.
ive got into the habit of checking the tank is full before I go anywhere , then around 100miles I start thinking about filling up again. As others have commented, mine shows apparently full until around 90 miles then drops off quickly. I know I can probably get around 120 miles safely. At my age stopping for a pit stop regularly is driven by other needs anyway!fd:doh:
 

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Hey buddy...I own a benelli tnt 300 and recently i have observed that the tempreture does not show up on the cluster..howver the fan works when it heats...any one could help???
 

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Funny this I have been thinking of using an arduino to monitor resistance across a chain of contacts And mapped to volume but haven’t gone into any detail yet. Biggest problem is waterproof housing for the arduino.
My fuel gauge is pretty rubbish. Top few bars take ages to drop and the last bunch very fast, it’s not linear at all.
 

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Discussion Starter · #12 · (Edited)
Funny this I have been thinking of using an arduino to monitor resistance across a chain of contacts And mapped to volume but haven’t gone into any detail yet. Biggest problem is waterproof housing for the arduino..
If you were going to use resistance, a chain of thermistors top to bottom would do it.
Pass a current through them high enough to heat them in air and measure the resistance. That's empty.
As the fuel level rises, the thermistors are cooled by the fuel and the resistance changes.
That would require only two wires to penetrate the tank, so the existing ones can be re-purposed.

(Alternatively,measuring the

  1. inductance of the spring in the oem sensor might be feasible. TI has a chip made for the job.
  2. capacitance of 2 plates that extend top to bottom. The dielectric constant of fuel is double that of air so the capacitance changes with fuel level. The only question is the variation of the dielectric constant of different fuels - E10, 98RON, 95RON etc.
)

A FET to drive the existing gauge - adjusting the gate voltage & monitoring V & I to control the R.

Arduino or Pi for development, but the final processor should be a uC. Way smaller and more easily sealed in a housing. It's built-in supply should be protected against load dumps and reverse battery connection.


There wasn't much interest in a sensor that worked, so I haven't done anything about it. I figured I'd do it when mine died - again.
 

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Discussion Starter · #14 ·
Here's some pics of the sensor.
It's a variable resistor, so the dash is providing the source and responding to the resistance, so you need to emulate a resistance, not a voltage source.
My best guess is that the dash is providing a constant current and measuring the resulting voltage. That's how I would do it.
If you replace the resistor with a voltage source, it might not end well. Then again ......
What I was going to do, was use a FET with a resistor in the source/gnd leg, and use it to measure the current. Then measure the drain voltage and calculate the resistance. The uC will adjust the gate/source voltage to arrive at the required resistance.
It has to be a closed loop system because the Vgs vs Rds is by no means linear and temperature dependent. Font Display device Multimedia Electronic device Electric blue
 

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Hmm that original setup looks horrible. Might just go steampunk and glue fittings top and bottom and put a sight glass tube in:p
 
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