Is there a lead from the sending unit for a warning lamp for low fuel? Or is there a lead in the connector to the dash for one? I'm trying to recall from memory(since I'm not near the car, and my FSM is at home).

Thanks,
Derek

Don't we all wish.........

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'85 SE - '86 Fastback SE - '99 Chevy K-1500 Z-71 - '00 HD 1200XL Sportster

The low fuel warning is a sound of the engine hiccoughing and the car starts bucking. This tells you you have no more fuel. This usually happens after 200 miles of driving with a full tank.

quote Originally posted by Old Lar: The low fuel warning is a sound of the engine hiccoughing and the car starts bucking. This tells you you have no more fuel. This usually happens after 200 miles of driving with a full tank.

lol! So from the responses I'm guessing no.

Yes!!! You will use fuel gauge sender wire. All 80's Gm's read 0>90 ohms. The hard part (GM no longer makes them)is finding the little circuit board & light that the Corvettes and others(Buick Regal, I,ve forgotten them at the moment) used. These little circuit boards simply plugged into the early 80's dashes. Basically, there are 3 contact points on the board, pos, neg, sender. Just solder some wires up, mount your idiot light, and splice in.
I went through this about a year ago, and recieved alot WHY? etc, so I didn't bother to post the build. There is also a place in Australia that produces an electronic kit to do the same, I think about $35. Ebay sells the GM circuit brds occasionally, but the people selling KNOW they are valuable! I bought mine from Corvette Central. Took a bit of searching but I found the website for the GM board.... scroll down 1/2 a page
http://tlentz.oldsgmail.com/tips.html
good luck, I'll just wait for the guys that come on to say you don't need it, that theirs gets 60 miles per gallon, etc!@ But with me, heh, a V8 eats gas the way I drive it!
Sandy

quote Originally posted by cowans: Yes!!! You will use fuel gauge sender wire. All 80's Gm's read 0>90 ohms. The hard part (GM no longer makes them)is finding the little circuit board & light that the Corvettes and others(Buick Regal, I,ve forgotten them at the moment) used. These little circuit boards simply plugged into the early 80's dashes. Basically, there are 3 contact points on the board, pos, neg, sender. Just solder some wires up, mount your idiot light, and splice in. I went through this about a year ago, and recieved alot WHY? etc, so I didn't bother to post the build. There is also a place in Australia that produces an electronic kit to do the same, I think about $35. Ebay sells the GM circuit brds occasionally, but the people selling KNOW they are valuable! I bought mine from Corvette Central. Took a bit of searching but I found the website for the GM board.... scroll down 1/2 a page http://tlentz.oldsgmail.com/tips.html good luck, I'll just wait for the guys that come on to say you don't need it, that theirs gets 60 miles per gallon, etc!@ But with me, heh, a V8 eats gas the way I drive it! Sandy

Thanks for the info! I'll take a look at that site. For me the light is piece of mind, in case the gauge is out of whack. You don't happen to have a closeup pic of the front and back of the board? I'm electronics literate, so I might be able to build the board.

When I get below 1/4 tank, my fuel pump really buzzes loud. Its done it for 7 years, works for me. I WISH I got 200 miles on a tank.................

Sure, here are some pics...
Sandy

I like the idea of having a low fuel light.... just makes the car seem more complete. I'll be on the lookout int eh junk yard for that circuit.

www.GMPartsDIrect.com doesnt have a listing for the part #. I will have to check the junkyards and see if they have any.

I like the idea of a light telling me that my car is thristy.

The Boneville HUD that I put in my car has a low fuel warning light, and I assumed it would work similar to the circuit you showed above but I haven't tested it by running low on fuel.

I dont have my fiero with me so i can't get out and look... but is there an unused low fuel light icon in the intrument cluster much like the buick's in the above link?

Wow, that looks really simple!! Sandy, do you know if there's a part # listed on the 3-pin transistor looking part on that board? Seems like that's all it is, just a few resistors to control the on/off of the transistor, and a capacitor to smooth out the input. With the values of the resistors, that capacitor, and that transistor, anyone could make the circuit for like $5. You could most likely even replace one of the resistors with a variable and set the "on" point to whatever you wanted. Nice find! I had planned on building it into a circuit for a digital gas gauge, but man that looks simpler! Oh yeah - there's no "fuel" light in the Fiero instrument cluster, but if you have an empty "upshift" light, you can replace that picture with a "fuel" light of your making, or take one out of another cluster and cut / paste it in. The little cross pieces on the cluster bezel should hide the cut lines.

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Bob Williams
Multi-colored '86 Mutt, a work in progress! (3800SC is installed and I'm driving it! AAAAAAAAAAAGGGGHHH!!! This sucker is FUUUUUUUUUUUN!!! )

[This message has been edited by Riceburner98 (edited 01-25-2005).]

quote There is also a place in Australia that produces an electronic kit to do the same, I think about $35

My old 84 Cherokee had one, but I sold the thing last Oct, and gave the buyer my book with the wiring diagram. Real accurate and you had 2 gal left after the light came on fully bright.

Question: Since it uses the sender wire for input, doesn't that mean that the low fuel indicator would be only as accurate as the sender? As far as I know, mine is ok, but my wife has run completely out in hers with a little less than 1/4 tank showing.

Any chance you would still remember the name of this Australian outfit? (Where's AusFiero when you need him?) I guess I'm like a lot of Fiero owners--so overly conscious of our inaccurate gages that I rarely let mine get under 1/2 tank. I've never run out yet, but it would sure be nice to know I was about to. Thanks Cowan! A + for you.

[This message has been edited by maryjane (edited 01-25-2005).]

Seems there is some interest! I'll try and answer some questions....
No, there is no low fuel light in the Fiero cluster. but you could use the "upshift" slot as 'Riceburner98' stated. I have a custom dash that doesn't use the Fiero guages.The GM part# is listed on the link above... (GM Part #6432974) you have to read through most of it. (GM does not make this part any longer). I will be removing the light bulb and replacing it with a 'standalone' one
The Aussie Co can be found in a Pennock link (old) and I'm not sure if the company is still around! I think Tom Corey purchased one but I never heard back...
Ahh, here's the link
https://www.fiero.nl/forum/Archives/Archive-000002/HTML/20030531-1-024908.html
For those electronic gurus, I'm sure you could put this together for <$10.!
The unit is only as good as the tank sending unit.... in other words, if your guage shows empty and you really have 1/2 a tank, the idiot light will be ON!
Sandy
...Sorry 'Riceburner' just reread your post. No I don't see any #'s....

[This message has been edited by cowans (edited 01-25-2005).]

Here's another idea http://www.westol.com/~beaurega/gas.htm

That's Ok.. I'm sure it wouldn't be hard to duplicate if someone wanted to. But yeah, the accuracy of the tank sender definitely comes into play here.. A "universal" GM replacement from Summit or someplace like that should be less than $40 though, assuming your tubes are in good shape and all you have to change is the sender.. I personally seem to have the "run-out-of-gas-a-lot" gene, as I've done it probably 4 times in the Fiero... Guess I always think I have "just enough" to get to the next station! Harder to ignore if you have a bright light saying "get gas stupid!". LOL Once I ran out right across the street from the gas station. Just not enough to get it across. Good find Spark! That's exactly the circuit you'd need. Seems GM just did it in a 3-pin device instead of the usual Op-amp.

[This message has been edited by Riceburner98 (edited 01-25-2005).]

I bet that there are two transistors on that board and that the circuit looks a lot like the one used to light the oil warning lamp on the rally gage shown here:

Somebody correct me if I'm wrong, but didn't I see a thread a while back about someone that tried to get a new sending unit and had a REALLY bad time ? Seems that GM discontinued them and none of the universals would fit; I think he ended up getting one from a junk yard.

Theoretically, I guess you could use lights based on the circuit board without a gauge; (1) for FULL, (1) for 3/4, (1) for 1/2 , (1) for 1/4 and (1) for LOW ?

Somebody let Lawrence at WebElectric know that here's an opportunity ...

[This message has been edited by PaulJK (edited 01-26-2005).]

Been looking around a little too. There are a couple of kits around, and on DIY deal. Also saw another link that correlated what Cowans said about the mid 80's Cutlass.

This is the same DIY info Spark1 posted using off the shelf Radio Shack parts. I'm guessing the 2nd schematic and parts list for the GM vehicle is what we would want, but seems more complicated than going to the junkyard.
http://www.westol.com/~beaurega/gas.htm

This kit looks a lot more simple to me, and the price is right.
(edit) I had a link to a little kit that was 12.95, but danged if I can find it again now)

[This message has been edited by maryjane (edited 01-26-2005).]

When I did my 3.5 S* swap I used a Corvette pump and the 2000 Olds intrigue sending unit. I also used the Olds gauges, so I now have a Low Fuel Light, Change Oil Light, Low Oil Light, Low Coolant Light, it tells me what gear I am in and more. It is cool.

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quote Originally posted by Riceburner98: I personally seem to have the "run-out-of-gas-a-lot" gene, as I've done it probably 4 times in the Fiero... Guess I always think I have "just enough" to get to the next station! Harder to ignore if you have a bright light saying "get gas stupid!". LOL

I have that same gene! HEHEH!
lots of good info....
Sandy

[This message has been edited by cowans (edited 01-26-2005).]

OK, FWIW, I built the low fuel display according to the schematics at http://www.westol.com/~beaurega/gas.htm . Use the circuit listed by the author for the Chevy van as it uses the same sender values common to all GM's. I'd estimate the cost with Rat Shack parts at something along the lines of $15 which included 5 packs of resistors, two DIP Sockets, two IC's, a few LED's and some misc. colored wire. That was enough parts to build two complete units.

After I had it working, I hooked it up to one of the cars that we had drained ALL of the fuel from when we replaced the fuel pump. The tank was bone dry since we actually steamed it out to remove 5 years of varnish and crud as it had set unused for that long. While it was apart, I also cleaned the resistor pack in the sender and checked it with an ohmeter to verify that it had linear and accurate response. I then put 1 pint of fuel conditioner in the tank and exactly 1 1/2 gallons of fresh gasoline.

The voltage showed at that point to be 2.98 volts on one digital voltmeter and 2.96 volts on another, which is pretty darn close. The gauge read right at 1/4 full at that point and it measured about 32 ohms to ground, although I didn't really write that down since the switching voltage is what the IC is looking at. I then trimmed the pot so that the LED would flicker very slightly at rest and more pronounced when the car was bounced.

After the car settled and the fuel stabilized in the tank, the light was still on, so I tweaked it just slightly so that the light was on steady. This required a miniscule movement of the pot. I then added 1/4 pint of fuel at a time and by the time I was putting the 3rd 1/4 pint in the tank, the light went out. When the car was bounced, it again flickered, so it's doing it's job.

I actually tried to build it the first time as suggested in the instructions on a 16 pin dip socket, but for my soldering skills that was too precise of work to have it come out successfully. I then used a Radio Shack 276-159B DIP board that measures about 2" square. This is more than large enough to do the job and I used an 8 pin DIP socket for the IC. Once I had the values set on the pot, I set it with hot glue. I also put dabs on hot glue on my wires to act as a light strain relief.

I had to make a couple of substitutions from the plans. The plans call for a 9200 ohm resistor and the parts list calls for a 10K so I used the 10K and it worked fine. Since the plans don't specify tolerance (5%, 10%) I used a 5% and that would still most likely fall in specs for a 10% 9200 ohm resistor. It worked fine. Radio Shack also didn't have any 2.5K ohm PCB mount pots in stock so I used a 4.7K pot. That works fine, but it makes setting it just a little more touchy, but certainly not too bad to make it usable. I also board mounted an LED as well as including the leads for a remote mount LED. I used the board mounted LED to trim the pot and now that it's done, I'll take it off and just use the leads to the remote LED when installed in the dash.

I'm going to either pot the entire unit or mount it in a small, plastic box and pot it in there. I haven't done any electronic kit work in almost 20 years and really enjoyed doing it. You could mount the LED in an unused position on the dash (shift up, etc) if you wanted to use the stock dash. If I can build it and make it work, anyone can. My low fuel light will now light when there is just under 2 gallons of gasoline in the tank. I'd guess that to be closer to 1 gallon or a little more of USABLE fuel in the tank, as my tank was bone dry when I added the fuel and you'll never get the pump to remove 100% of the fuel from the tank left on it's own.

John Stricker

Nice going John. Hey, since you had enough parts to make (2), I'd be interested in buying the other one from you ...

The name of the Australian outfit selling the kit is Dick Smith Electronics. About $15. I still can't find the link to his ad, but will try again after I get a few hrs sleep. Here's what the completed gizmo looked like in his ad. The kit info also mentioned using a special led as an option
that changed from white to yellow, to red as the resistance in the fuel sender changed. There was akso a specific resistor, that provided a 10 second delay to prevent the low fuel light being illuminated prematurely when you went over a bump or accel/decelled. The led can either be board or remotely mounted--or both, as John did his.

[This message has been edited by maryjane (edited 02-12-2005).]

Don,

If you go to the archived thread there's a link to the Dick Smith electronics website. Unfortunately, when I did a search for the p/n of that kit on his site, it came up empty so I don't believe they're making that kit anymore.

Paul,

I'm actually planning on using the components for another one but instead of using it for a low fuel, I want to use it for a low oil pressure annunciator. The Fiero OP Sender has the same range of 0 to 90 ohms so the same circuit will work for that as well. It wouldn't really take much to pick up enough stuff at Radio Shack to make 10 of them, probably cost about $25 in parts, then I could package and sell them for about $15 a kit and make a nice, tidy profit.

The parts, though, would be cheaper coming from Digikey or Mouser than Radio Shack.

John Stricker

Glad it worked out for you John..... To others, follow John's build experience or buy a circuit board from a junker! I think a homebuilt one would be more pleasurable, considering the low cost!
good luck, Sandy

quote Originally posted by maryjane: The name of the Australian outfit selling the kit is Dick Smith Electronics.

Here's the link to the Store Front for Dick Smiths:

Dick Smith's Site

I could not find the link to show what you have listed...can you post the direct link please?

John, are you planning on making a few of these?

--Allen

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From what I can see of the little module and the rally gauge schematic... You should be able to build those really cheap. I agree with spark that they are probably the same circuits. May have a different resistor to change the set points.

The transistors probably aren't very critical. Any small NPN like 2N2222 would do. Any small signal or light duty rectifier diode will probably work for that. By the look of the scematic, the capacitor is to help prevent random/slosh activation if there is a momentary spike on the line.

According to the diagrams I have, the oil pressure sender runs in the same range of resistance as the fuel sender. "90 ohms max at full pressure," "90 ohms full" on the tank.

For a one off thing you could just use a chunk of little perf board to give the parts support. You can even use "pad per hole" perf to give the transistors a bit of support. The resistors and other parts often have enough lead on them that you probably can stick them tru the perf and solder them together with little or no wire. The board doesn't have to be right on the lamp.

You may have to modify a socket to hold the lamp. That could be a little tricky to do w/o breaking it. You could probably use an LED with the circuit but you'd probably have to add a ballast resistor to keep the LED from burning out.

If someone can get the resistor values for the OE module it would help. It looks like they have standard color codes on them still. Just list the colors on them if need be.

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The only thing George Orwell got wrong was the year...

The Ogre's Fiero Cave (It's also at the top of every forum page...)

I really don't think the board can get much simpler than this. 3 resistors, 1 pot, and the IC which is less than $2 IIRC. As you can see, the board is more than large enough and it measures 1.75" square. Depth is about 1/4" not counting the LED on it, which will be removed when it's installed.

I used this circuit:

It came from the website by P. Beauregard and is copyrighted by him but he says it's free to share for NON-COMMERCIAL use.

I really don't see how it can be much simpler than this one. The picture of the one Don posted has over twice the parts count and is about the same size. The parts count of the factory circuit would be higher as well.

John Stricker

Evidently, the Dick Smith kit is no longer available. Here is the text next to the picture I posted.

Low Fuel Indicator
Costing just $15.10 (through Dick Smith Electronics), this kit activates an on-dash light to tell you whenever the fuel level has fallen to below a preset level. It says, ""hey, it's to time to gas me up!" Any fuel tank with an internal fuel gauge sender can be used with this kit. Comes complete with dash light and a box. (It can also be used to switch a relay (or the light) when an engine management sensor exceeds a pre-set voltage!)

Difficulty rating: Simple

I found this one on an autommotive magazine site-several years old.
http://www.autospeed.com/cms/article.html?src=suggestions&A=0828

Mr. Beauregard makes mention of damping of the circuit and decided to leave it undamped, which I agree with. I set the level low enough that the sloshing of fuel in the tank when it gets low will make the light come off and on. A flashing, or blinking light is much more noticeable than one that is simply on steady so the way it works when the fuel gets close to that point it will blink occasionally, then more often on than not, then on steady. This will give a good indication as to how close you really are to the set point.

Another method that I thought about was to build two circuits on one board and use a bi-color LED, one that came on with the first color at a setpoint and then the second color at a lower setpoint. Not sure if that's worth the trouble or not, but it's something to play with.

The circuit looks at a difference in voltages. The voltage shown between the hot wire and the voltage coming through the tank sender wire. One thing to note, though, is that when you hook this up to calibrate it, the gauge has to be in place and working and the key on so that there is a voltage coming through the sender wire and not just a resistance to ground, or you'll never get the LED to shut off as there will be 0 volts at the wire. That made me scratch my head for a few minutes when I couldn't figure out why I couldn't trim the pot enough to get the light to turn off without the key being on, I thought I'd screwed up something in the circuit until I remembered the IC was comparing voltages and not resistance.

John Stricker

At least for Fiero and some other older GM cars... The oil/fuel gauges and senders are esentially the same system electrially so any light that works for one should work for the other. It is just a matter of picking the point where you want them to turn on.

Damping/delay on the circuit is sort of a personal thing.... People who tend to run with low fuel levels will probably be bothered by a flashing light more than people who fill the tanks at each visit to the gas station.

The opamp version is nice because setting the activation level/pressure is fairly easy. By the time many factory oil lights turn on you've already got damage in progress. Even 20PSI is low enough with most engines to greatly accelerate wear. (Spec on all OE Fiero engines is up in the 35-40PSIG range.)

This looks like an easy, fun mod. Since we've got the interior gutted for other upgrades it's a good time to add a low fuel sender. In case it helps here's the Radio Shack part numbers...

(1) ECG941 or MC1741 operational amplifier. Single supply, 5-15 volt, 741 Op Amp IC5, RS # 276-007
(1) 8-pin IC socket for the IC, RS276-1995
(1) 220 ohm 1/4 watt resistor, RS #271-1313
(1) 2,200 ohm 1/4 watt resistor, RS #271-1325
(1) 10,000 ohm, 1/4 watt resistor, RS #271-1335
(1) In-line fuse holder, RS #270-1238
(1) 0.5 amp fuse (or less), RS 270-1047
(1) 1.75" square, copper, one-sided, DIP board, RS # 276-148

(x) 2.5K, 1-urn potentiometer for dynamic adjustments. RS does not have this.
(x) 4.7K, 1-turn pot will work, RS #271-0281, now discontinued.
(1) RS recommends the 10K / 15-turn pot, RS #271-343 (will try it and see)

Now, it seems building the Low Fuel Indicator is only half the battle. Where will it be mounted? We'd like to use the "phantom idiot light" socket (located on the right bank of idiot lights, under the right arrow turn signal.)

The electrical wiring doesn't appear to be difficult. However, our lens (not sure of the correct name for the acetate strip with the icons) is blacked out. Need one of those graphic fuel pump icons and a way to overlay it on this lens. Thinking...

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Steve, 87 Fiero GT, Getrag w/Ultimate Shift Kit, Street Dreams drop spindles, Poly mounts, KYBs, Borla exhaust, Pioneer audio, DashScan

quote Originally posted by maryjane: Evidently, the Dick Smith kit is no longer available.

But I managed to pick one up for you anyway. Last one in stock at that store too. Only 2 more left in the country.

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Steve,

We're going an entirely different direction with the light as far as mounting it goes so I can't help you with that.

Now I know why RS only had one of the 4700 ohm pots and couldn't find the number for the one they had. I looked at the 10K 15-turn pot and it should work fine. I think I ended up with it measuring about 1800 ohms or so to get it to come on when needed, but don't quote me. The important thing is the higher the range, the touchier it is but the 15 turn adjustment should take care of that. It is over twice the price, though, at over $2.

John Stricker

quote Originally posted by SLagrec1: (x) 4.7K, 1-turn pot will work, RS #271-0281, now discontinued. (1) RS recommends the 10K / 15-turn pot, RS #271-343 (will try it and see)

Mounting will depend allot on the light you use. A 194 lamp won't fit allot of places. Cars with automatics could use the upshift hole.

You could mount a tiny LED or lamp on/behind the gauge itself if you don't mind making a small hole in it, say near the E. There are a couple ways to go with that. You could have the LED show directly thru the hole (I would go with an LED mainly because you will likely be gluing things together this way. No heat and more reliable.) or use a realy small LED clip and mount the LED in the hole. The smallest clips and lenses I see so far want a 4-5mm mounting hole.

Alternately find some bit of excess idiot light symbol plastic that you can rob. It often over hangs the lights quite a bit, and you only need a tiny piece. Or rob some from another gauge cluster. Glue this over the back of the hole and then glue the LED in place behind it. Cover the back of the LED with black silicone to keep the gauge lights from shining thru your new indicator. Using the plastic would give the hole in the gauge a factory look when the light is off.

You may want to play with the ballast resistors on an LED to dim them down some. You don't want it blinding you at night.

IF you have a strand or three of fiber optice cable, say from disused Christamas decorations, you could use that and put the actual lamp anyplace. Digikey shows a fiber in the current catalog that might work. (page1514) There are all sorts of options.

Thanks guys, really appreciate the ideas! Hadn't thought about mounting the LED in the aux gauge pod. Maybe we can get the LED to illuminate the fuel pump icon Will let you know...