Clever way for fuel level measurement? weight?

Looking for some alternative ways to determine fuel level in my Radical without having to drain and refill. Best idea I could think of is to bring my scales to the track and determine by weight. However that's a lot of work, sort to speak not to mention having to run all the wires.

Pots on shocks was another idea, but not sure how accurate that is.

Any thoughts? The fuel bladder is not accessible and a very complex shape. I can't throw a dip stick or equivalent, nor install a fuel level sender.

Arax

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What about using a math channel to calculate it? My 2004 PFM did this on MoTeC. There was no fuel flow meter if I recall correctly.

fill the cell to start. Then use an electric pump, pump out to your required level.

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Originally Posted by 99sh

Looking for some alternative ways to determine fuel level in my Radical without having to drain and refill. Best idea I could think of is to bring my scales to the track and determine by weight. However that's a lot of work, sort to speak not to mention having to run all the wires.

Pots on shocks was another idea, but not sure how accurate that is.

Any thoughts? The fuel bladder is not accessible and a very complex shape. I can't throw a dip stick or equivalent, nor install a fuel level sender.

Arax

Sent from my Pixel 7 using Tapatalk

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In my opinion, the best way to do this is to make an efficient way to pump the tank using your fuel pump. Then each session you can pump the tank out, record fuel used, and refine the fuel usage for different tracks. Very accurate and simple.

-Mark

Install a Jiffy-Tite (3000 or 5000 series) female connector in an easily accessible section of your fuel line using a T fitting. Then use a mail Jiffy-Tite connector with a hose barb and long clear hose that will reach a fuel jug. The car fuel pump can be used to pump out existing fuel. We also used this as a fuel sample port. Fill your fuel cell to full capacity, then pump it all out to determine your actual useable fuel capacity as most fuel cells have some unuseable ullage. Then you can load up the specific amount of fuel you need for the particular on-track session.

Not sure what level of accuracy you are after, but bear in mind that fuel specific gravity varies by up to 7% depending on brand, octane, additives, where you buy it, etc., so weighing the car for residual fuel can be variable.
Pumping out into calibrated jugs is the way to go if you can add fittings to the fuel system.

If the fuel pickup is at the bottom of the bladder you could put a Tee in the line with a clear vertical sight gauge.
A shut off valve on the Tee to inactivate after checking would be worthwhile.

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Originally Posted by jrh3

If the fuel pickup is at the bottom of the bladder you could put a Tee in the line with a clear vertical sight gauge.
A shut off valve on the Tee to inactivate after checking would be worthwhile.

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Other than pumping out, this is a clever alternative.

If you are running significant ballast in your car, remove it, or some off it, so that you can run full fuel all the time.

If you religiously monitor laps/minutes run, I would think that you can establish very accurate fuel consumption numbers so that pumping out could be an occasional activity. I know our cars have less power, but we use less than 1/2 gallon difference at all tracks in a 25 minute session. To me, it is easier to pump out than it is to monitor minutes of usage, but this is a multi-car team with rotating mechanics, etc. If you get all your hardware organized, it becomes a 5-10 minute job, while you do a nut/bolt check or eat a sandwich.

Are you unable to add a fuel level sender by rule, or is it more of a practical constraint?

If it's the latter, a submersible hydrostatic pressure-based sender could be the ticket, perhaps with an additional interface to correct for the geometry of your fuel cell and environmental conditions.

Similarly, a custom capacitive sensor could be the ticket as long as you can get at least a few wires into the bladder extending from its bottom to its top to serve as sensing and reference plates. I'm currently in the process of implementing such a system on one of our race cars.

Jeff

1. Fill all the way...drain and refill......it's the best way
2. If not going to do so......problemchild has the easiest way - it will just take a while to get an approximation.........go out full every time, come in and see how much you add versus the time spent on track...........be sure to find a few sessions where you'll be out on track for 30 - 35 minutes.......it will take many sessions to figure your mileage versus time.....but it would less mechanical work than fill - drain - refill
3. Run until you run out of fuel......fill.........remember engines leaning out can get hurt.......3a) maybe after a long on track session, bring it in, shut it off, let it cool, run at idle until out of fuel.....fill.
4. One needs to know just how big their bladder is. (Especially when preparing for a long tow to the track :ha:)

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Originally Posted by jrh3

If the fuel pickup is at the bottom of the bladder you could put a Tee in the line with a clear vertical sight gauge.
A shut off valve on the Tee to inactivate after checking would be worthwhile.

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For this to work, the 'sight gauge' would need to be vented back into the top of the fuel cell.

Curious what clear material you would recommend? A vibration or other type failure of this sight gauge would drain your fuel cell into the vehicle while running and you might not know it until very too late :(

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Originally Posted by Lotus7

For this to work, the 'sight gauge' would need to be vented back into the top of the fuel cell.

Curious what clear material you would recommend? A vibration or other type failure of this sight gauge would drain your fuel cell into the vehicle while running and you might not know it until very too late :(

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Closing the manual valve on the tee after filling would eliminate the failure problem .
Aerobatic biplanes having used this system without a valve for a very long time.

Unless you make the sight gauge removable, like a sampling port or such, I foresee a problem at tech...
" A piece of GLASS in your fuel line ???"

How about some clear line sold by 'OnFireGuy' :D
https://www.amazon.com/Premium-Perfo.../dp/B00M1W542E

Run it from a port at the bottom to the filler vent....

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Originally Posted by BeerBudgetRacing

How about some clear line sold by 'OnFireGuy' :D
https://www.amazon.com/Premium-Perfo.../dp/B00M1W542E

Run it from a port at the bottom to the filler vent....

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Of course…..

What I did on my 598 S2 that had a strange filler is the following. I inserted a 1/4" hose down the filler neck to the bottom of the cell. I left it in the cell at all times and had enough extra to pull out a few inches. I then would use an electronic pressure gage available from Amazon along with a pressure bulb from a blood pressure cuff. As the level of fuel rises, the pressure required to overcome the increase in depth increases. Calibrating by 1/2 gallon increments allowed me to hook up to the hose, couple of pumps to reach the maximum pressure (air coming out of bottom of tube) and you have what is in the cell. Worked great and was amazingly repeatable. Just my $0.02.

PS Many large tank gages work the same way.