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Fuel transfer indicator


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My Jodel has three fuel tanks, i.e. one main, and two wing tanks. The engine runs from the main tank, and an electric Facit pump is used to transfer fuel from the wing tanks to the main. There is an indicator light to tell me that the pump is running, but there is no way to easily tell if it has finished transferring fuel and is running dry, or is still pumping fuel. I don't believe it is good for the pump to run dry, but can't think of an easy was to determine this. Does anybody have any ideas?

 

 

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This is probably a pretty crappy solution, but its quick and dirty:

 

Does the current drawn by the pump change when its pumping air as opposed to fuel? might be easy as sticking a (milli)amp meter on the pump.

 

 

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This is probably a pretty crappy solution, but its quick and dirty:Does the current drawn by the pump change when its pumping air as opposed to fuel? might be easy as sticking a (milli)amp meter on the pump.

That might just work! The spec says the pump draws a max of 1amp at full load, I don't know what it draws when dry, but it is a 'pulse' type pump and the frequency of the pulses is slower when loaded than when not, without the engine running you can hear the difference. With your idea, even if the current doesn't alter much the needle might oscillate at different speeds for loaded and unloaded pulses. Thanks, I will track down an ammeter and give it a try.......that was quick, very quick....this site is just brilliant!

 

 

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I guess the main problem with that is you'd need to remeber to look at it and turn the pump off, and if the difference isn't big you might have a hard time noticing.

 

What about using a small microcontroller to count the pulses, and turn a light on when a slower pulse rate is detected - or turn the pump off? not really quick and easy, and a lot more effort to set up, but in the end a lot more convenient.

 

 

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I guess the main problem with that is you'd need to remeber to look at it and turn the pump off, and if the difference isn't big you might have a hard time noticing.What about using a small microcontroller to count the pulses, and turn a light on when a slower pulse rate is detected - or turn the pump off? not really quick and easy, and a lot more effort to set up, but in the end a lot more convenient.

That sounds ideal, but well beyond my capability, to me changing AA batteries is a big deal, let alone building microcomputers. It must be a common problem though, the Facit pump is just about the most common one in use, and there is probably a market for some smart cookie to build and sell such an indicator.

 

 

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What you are looking for is some proof that the pump is pumping. I would think a pressure gauge would be the answer. Either use 2 or put them in a common line between the wing tanks and the main tank. They would read a pressure when transferring and it would fall back to zero when the flow stops.

 

 

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What you are looking for is some proof that the pump is pumping. I would think a pressure gauge would be the answer. Either use 2 or put them in a common line between the wing tanks and the main tank. They would read a pressure when transferring and it would fall back to zero when the flow stops.

Yes, but I hesitate to put anything actually in the fuel line in case of failure. An electrical system that has no mechanical effect on fuel flow was what I had in mind. I suppose I could use an automotive fuel pressure gauge with a bypass line and shutoff in case of failure, but that is still adding complexity when what I was looking for was 'quick fix' of some kind.......lazy I suppose.

 

 

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hmm... how about just routing the fuel line up to the top of the dash? you'd see the fuel flowing easily enough then.

Actually there is a sight gauge tube in the dash, but the problem is that it doesn't show the top 1/4 of the nose tank, so once it is filled beyond 75% you can't see the level, and there is no visible indication of flow as there are no bubbles etc in the line just 100% fuel. I intend to try the ammeter idea this weekend with a multimeter, just to get an indication, and if it works I will buy a 2" ammeter from a car accessory shop and mount it in the panel.

 

 

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I had the same problem with the drifter belly tank (not knowing when the transfer finished) and had my fuel transfer pump blow up after running dry. I have fixed this problem by routing the mizer fuel flow in my A/C between fuel transfer line. I only use Mizer for caliberation of fuel flow at different RPM occasionaly. now the Mizer tells me exactly how much fuel is getting transferred and I hav'nt lost any more fuel pumps.

 

cheers

 

 

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