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A bit of background as to why I'm looking to build this and what it needs to accomplish.

I race motorcycles and as part of my prep work before each session of a race day (usually 3-4 times per race day), I drain the motorcycles fuel tank with a manual fluid extractor. This works with a tube inserted into the tank and a hand pump to extract the fuel. Once the tank is empty, I fill the extractor reservoir so that the total fuel is 6 litres and then I pour the 6 litres back into the motorcycle's fuel tank. This is to ensure that I have enough fuel to finish the race but not much more than I that.

So, I want to build an electric version of this that works with a fuel pump and a tube at each end of the pump. This would allow me to drain the fuel tank by inserting tube (A) into the motorcycle's fuel tank and tube (B) into a fuel container. Then once the tank is empty and the container is filled with 6 litres, I can reverse the order of the tubes to pump the fuel back into the bike.

So, my question is, what kind of fuel pump would I need to accomplish this? As far as I can work out, it would need to be an inline self-priming fuel pump, but I don't know much about fuel pumps. Also, what kind of specs would I need to look for to ensure that it does the job efficiently. Let's say it should be able to pump 10L from one end to the other in max 2 minutes.

Finally, do I need to be concerned about the fuel pump running without fuel passing through? When the tank is almost empty, for example.

Any recommendations would be appreciated. Thanks in advance.

Willem
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    Might be possible in one step: add fuel until correctly loaded. Would go something like: shove sensor & pipe on a stick into fuel port. Pump runs until sensor reaches correct level. Would need to manually fill and sense the correct reading initially, and to repeat inserting the sensor to evaluate consistency. – Abel Jun 24 '22 at 13:07
  • A great idea, but not really practical for my application. I sometimes need to increase or decrease the fuel amount that I put into the bike depending on how many laps we'll be doing. – Willem Jun 24 '22 at 13:13
  • Use two pumps - one to evacuate and the second to fill. https://www.amazon.com/TERA-PUMP-TRFA01-XL-Including-Auto-Stop/dp/B07SYM832J?th=1 – Phil Sweet Jun 24 '22 at 17:59

2 Answers2

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I did something similar and used an electric fuel pump from an older Rover v8.

Was capable of sufficient flow rate, and delivery pressure as well as it tolerated brief periods of intermittent fuel.

Very few pumps are designed to run dry for long periods of time.

Solar Mike
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Breaking the problem down, you need to sense the quantity, and you need to adjust the quantity in either direction (increase, decrease).

Moving the fuel into an external cobtainer provides an environment where it is easy to measure and control priming needs of pumps.

I still think you can manage it by sensing quantity inside the tank instead of the external container, and doing so would drastically reduce how much you need to pump, making the operation faster.

My reccomendation is to use a peristaltic pump. They do need to be primed (they self-prime but the conditions for it can be more difficult to achieve in both directions), but are essentially bidirectional and simple devices. You can pump fuel in to the tank to prime and then start drawing it out by reversing direction. Down side is that they tend to be slower (sensing fuel level in tank would help!), and spend energy in deforming the tube.

Abel
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