So I want to run only the critical gauges in my dash, that means no fuel gauge. My question: is there a way to wire a warning light that illuminates when my fuel level goes below a specific point? What kind of sender/sensor would i need? thanks david
It would be possible with a standard fuel level sender but you're talking custom electronics now. Try and find an electronic hobbyist to design a comparator circuit for you.
Running out of gas is pretty critical to me, but you could find a relay that trips at a certain ohm of resistance, then use whoevers style of gauge has that resistance as a lower fuel level. http://www.electrokits.com/Misc/12-Volt-Relay-Schema
how about using a stock sending unit-- take off the windings for the resistance, and solder a ground strip at a certain level, so when it reaches that point it will provide a grnd for a small light of your choice
It would probably be easier to put in a fuel guage than do this...but.... In the engine lab i work, we use liquid sensors all the time. Pretty reliable. We use them to fill tanks automatically when they reach a certain level, or trip a safety, if there's a leak. You'd have to weld a bung in the gas tank, though, to put the sensor in at the level you'd want it to send a signal. Then send power to it, and then to your warning light. They come in normally open, or normally closed configurations, you'll want normally closed, so it's not energizing a circuit when there's liquid present. GEMS is the manufacturer.
I agree with it being easier to install a fuel level gauge, even if it's hidden somewhere. Some motorcycles use a fuel level warning light. It requires a Thermistor to be mounted inside the tank, usually from the bottom. Should be an NTC Thermistor, meaning Negative Temperature Current. Basically it's a resistor that relies on temperature. When surrounded by fuel...it's cool. When the fuel level drops, the temperature of the thermistor goes up, as well as the resistance, and the light comes on. I think with a little research & Radio Shack parts you could make a warning light work with the stock sending unit at a preset resistance.
Suggest use sender ( plus tank if need be ) with the extra connection from a car with a fuel light, My current hack is a BX turbo, has warning light for fuel level, previous had a Triumph 2500TC also had fuel warning light, even my bike (YZF1000) has a fuel light, there must be others.
Be very careful in what you do to turn that indicator lamp on from the volatile atmosphere of that fuel tank. If you do something that is switching on that 12 volt dash lamp, the contacts in the switch will most likely spark at this point and you have a potential bomb on your hands.
Simple solution. No light at all. get yourself a 5 gallon tank and put it somewhere out of the way. Fill it and use it as a reserve tank hooked up with a tank switcher. When it starts to sputter switch tanks and start looking for a gas station.
Also depending on what you are building and the location of the fuel tank, there is a mechanical fuel gauge often used on boat fuel tanks. You might explore using one of these gauges mounted directly to the top of the fuel tank.
just put in a reserve tank, when the main tank runs out you switch to reserve. worked for early VW bugs
just thinking out loud....how about just using a VDO sender. you would need a indicator light that has two wires and not self grounding through the base. put power to one side of a indicator light and the other side a wire to the sender for a ground. the sender has 10 ohms empty and 180 ohms full , so when the tank is full the 180 should make the light glow dimly if at all. and when empty the 10 ohms is close enough to zero ohms that it should glow brightly you could experiment with a couple cheap resisters from radio shack and see if it works
How do the low fuel lights work on newer cars? Are they some complicated computerized gizmo, or could it be adapted to your application? My newer jeep has a little fuel pump that lights up, it works good, the fuckers on all the time it seems. Personally, the gauge on my 39 Pontiac hasn't worked in nearly 20 years, I just watch the odometer, go a 100 miles or so and fill it back up (400c.i. engine and a 12 gallon tank). I also carry a small can of gas with me just in case.
Alot of foreign cars use a reserve lamp. This is probably the best route to go, its already built in. Most older VWs and Porsche senders have the lamp circuit Mark
This is what I would do....make the sender a "go, or no go" circuit....as soon as the fuel gets low enough it grounds a lamp circuit through a relay. Simple.
Trip odometer. But seriously, fuel level ain't nothing to fawk around with. You like leaving your pride and joy along the road and walking for gas? For me it's a sickening feeling to imagine what could happen once it leaves line of sight. One thing you cannot control is how far the next station is when your light comes on. good luck
Could also hook up a temporary gauge and figure out roughly how many miles you get to the gallon then just keep your eye on the odometer... Say you've got a 10 gallon tank and get 20 miles to the gallon you know you need to start think about gas every 175 miles...
IF you know of someone that is electronic savvy they can build you this little electronic box or you could just install a fuel gauge, I would say that is a critical instrument. <cite>www.fizzindi.demon.co.uk/MX-5 Fuel%20Warning%20Light.doc </cite>
thanks everyone, I know fuel level is critical for everyday driving etc....but, i want the dash to be nice and clean. My plan was to run a speedo, tach, water temp and oil pressure gauge in a auburn style insert and thats it (nothing else will fit in the panel). I could and may run some gauges outside the insert but that will add visual clutter which i do not want. a fuel gauge is still an option for me, but i wanted to see if this was possible.
I don't tink I have owned an old car with a (fully) working fuel gauge. You should have a rough estimate of how many mile you get on a full tank right? Take that rough number and then drive and fillup accordingly. Am I missing something?
How about "hiding" a real gauge behind the dash somewhere and putting a discrete hole thru the dash/panel right over where your critical fuel level is. Then when it gets to that point, the needle will "light up" or be seen thru the hole, notifying you're at that point. You could also get an electronic guru to design something to use the fuel gauge sender's resistance to trigger an warning light too. Or just have a good pair of walking shoes handy.......
www.fizzindi.demon.co.uk/MX-5 Fuel Warning Light.doc There's your comparator circuit, complete with instructions.
My 70's triumph had a fuel gauge and a warning light. The warning light started to flicker at about 1/3 tank, blinked steadily fron 1/4 tank and came on solid as the tank got toward empty. Being 70's there was no electronic gadgetry involved, just the sending unit in the tank which had an extra wire running from it. If you could find a similar setup you could run the right sort of sender in the tank, forget the gauge, and just hook up the warning light wire to a small light. I don't know, but I'd guess many imported cars, English European etc, would have a similar setup if the US cars didn't. Cheers, Glen.
Bravo. right outside the old envelope there. Got a friend that has an autometer gauge, but travels with a 1 gal plastic tank. He runs the truck completely out, then dumps in the gallon. when I asked why he had the gauge at all, his response was "it came with the set"
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