Question: How Low Can We Go? :)

[GerryLP]

Hello folks,

Long time no-posting salutations. I finally got a replacement low fuel warning module for Gail, but I can't remember when about I am supposed to see the low fuel warning light glow. The owner's manual says at approximately 2 gallons left. I drove the vette until the needle was pointing the space between the red-highlighted area and the,"E". But no light.

I even slalom the vette a bit to see if i could make it to light up; however, it did not. I added 6 gallons of fuel, and the needle went to just left of the half of tank mark.

I read somewhere in which it said that the fuel tank has 5-1/2 gallons when the gage needle points to the 1/4 tank mark. If this is correct, that means Gail had approximately 3 gallons in the tank when the needle was pointing between the red zone and E (because how it behaved when I added 6 gallons).

What have been your experiences? I am sure not all L81's are the same when it comes to the circuitry and its parameters for the fuel gage, but at least your recollection may help me determine if my new low fuel warning module is working correctly.

Thanks!

 

[Nut]

Hello folks,

Long time no-posting salutations. I finally got a replacement low fuel warning module for Gail, but I can't remember when about I am supposed to see the low fuel warning light glow. The owner's manual says at approximately 2 gallons left. I drove the vette until the needle was pointing the space between the red-highlighted area and the,"E". But no light.

I even slalom the vette a bit to see if i could make it to light up; however, it did not. I added 6 gallons of fuel, and the needle went to just left of the half of tank mark.

I read somewhere in which it said that the fuel tank has 5-1/2 gallons when the gage needle points to the 1/4 tank mark. If this is correct, that means Gail had approximately 3 gallons in the tank when the needle was pointing between the red zone and E (because how it behaved when I added 6 gallons).

What have been your experiences? I am sure not all L81's are the same when it comes to the circuitry and its parameters for the fuel gage, but at least your recollection may help me determine if my new low fuel warning module is working correctly.

Thanks!

Gerry.... I'm sure each car is different with regard to the light vs remaining fuel amt. On the ole Nutmeg I would get the light about the time the needle hit "E". But then again I had an annoying bouncing needle due to a wire short to GND that I could never track down before I sold her and I never knew if she was "exactly" on "E" or not. Anyway, if I'd fill to the brim she'd take about 19-20 gal. This assumed I still had almost 4 gallons remaining. I never had the "nuts" (excuse the pun) big enough to run her dry just to see how far she'd go after the light went on. I never wanted to risk sucking junk from the bottom of the tank. Did you check the bulb? I know it's a silly question. And perhaps be sure that flimsy flex circuit board is getting good contact at the bulb connection?

Good luck. My wife is retiring end of this school year and we're way overdue for a trip back to Albuquerque, Santa Fe and Taos again. Will definitely let you know if/when we're in the area.


nut

 

[GerryLP]

Gerry.... I'm sure each car is different with regard to the light vs remaining fuel amt. On the ole Nutmeg I would get the light about the time the needle hit "E". But then again I had an annoying bouncing needle due to a wire short to GND that I could never track down before I sold her and I never knew if she was "exactly" on "E" or not. Anyway, if I'd fill to the brim she'd take about 19-20 gal. This assumed I still had almost 4 gallons remaining. I never had the "nuts" (excuse the pun) big enough to run her dry just to see how far she'd go after the light went on. I never wanted to risk sucking junk from the bottom of the tank. Did you check the bulb? I know it's a silly question. And perhaps be sure that flimsy flex circuit board is getting good contact at the bulb connection?

Good luck. My wife is retiring end of this school year and we're way overdue for a trip back to Albuquerque, Santa Fe and Taos again. Will definitely let you know if/when we're in the area.


nut

Hey Nut!

Yeah, let me know if you are coming to NM or passing through, either way. It would be great to see you, man.

I am suspecting that I stopped my test drive too soon on the Vette. Next test I will have three gallons of gas with me on a 5 gallons bottle and either run out of gas or get the light to light up.

 

[the boss]

I don't know if the connector for the fuel gage is easy to reach, bust the best way is to back probe the connector to simulate the signal for a low fuel condition. If the light comes on during simulation, then you are sure the entire circuit is ok and the problem is probably in the fuel tank. You have to find the wiring diagram or post the exact model year, engine and tranny and I will look at the shop tomorrow and try to post the diagram. If you want, post an email address because I never tried to post a wiring before and not sure if I can. Steph.

 

[GerryLP]

I don't know why GM did not incorporate a light bulb check on the low fuel warning. When you run out of gas is not the best time to find out that the light does not work. lol

I have the wiring chart for the L81, so thanks for the offer. It is just that it now has a new module, and I am trying to find if it works before the warranty runs out. I only drive Gail on a Friday to work, if work allows it. I don't like driving her to meetings and the like (just work and back)

 

[Antz81]

as we work with litres here i cant be 100%, but believe i have around 5-6 gallons left when my light comes on. This is between the red highlighted area and "E".

 

[Peer81]

When the low fuel light comes on also depends on that color resistor is behind the gauge. Besides that the module has a buffer with a .. sec delay on the signal so you don't get a blinking light. So if you want the light to come on drive in a cirkel and not slalome.

I have a aftermarket one that gives a continued low fuel light when there is about 1/3 left in the tank and starts rappidly blinking when there is 1/6 left in the tank. When i stop at a fuelstation i can get 70 to 75 liters in it (empty tank from my own experience is 80 - 82 liters). So that gives me 10 liters (3 to 4 gallons) remaining in the tank.
As this low fuel unit doesn't have a buffer the inregular blinking light in the corners is pretty annoying (something for the to do list).

But as said the best to do is drive around with some extra fuel in a can. As the fuel pickup in the tank is 1/2 to 1" above the bottom sucking up dirt isn't a problem. And if it did then that would give you a good excuus to replace the carb fuel filter.

Greetings Peter

 

[Tom Bryant]

Ours doesn't get much below half before we fill it up but I do remember the light coming on with the needle on or around the empty mark. I have never ran it out so I can't say how much is left at that time. It would be a good thing to know though.

Tom

 

[6880 Mike]

I believe the owner's manual says three gallons in the tank when low fuel comes on.

 

[Yoda]

Gerry

Well, from one ANAL car guy to another

I don't remember ever seeing the fuel light come on in RARE. I am too ANAL to run ole RARE that low on gas otfl

I know you just want to find out if the fuel low level light works, but (You know me better than most) I doubt you would EVER let GAIL run out of gas :nono.. As Nanc would say "You are obsessing again"

Hope you get this figured out and can get a good nights sleep

Luv ya Man

Bud

 

[GerryLP]

I wish I could say that, Bud. But the low fuel warning light has saved my rear a couple of times in those long distance returns to NM. In fact, that one time we parted ways in St. Louis, I was in major cruise control, and were it not for the low fuel warning light, I would have run out of gas. I actually decided then to take a room at a Comfort Inn, near the gas station, and called it a night. :ugh

 

[GerryLP]

as we work with litres here i cant be 100%, but believe i have around 5-6 gallons left when my light comes on. This is between the red highlighted area and "E".

Antz,

you are not too far off the mark. The light should come on around 7.5 litters of gas left. But i am beginning to think that it is more closely relate to what is left in the tank, than to needle position.

 

[Antz81]

Antz,

you are not too far off the mark. The light should come on around 7.5 litters of gas left. But i am beginning to think that it is more closely relate to what is left in the tank, than to needle position.

From when i had the gauges out it looked as though the light was independent of the gauge, but still ran off the same sender.
If it helps when i fill i get around 70 litres (18 gallons) into the tank when the light has just started coming on.

 

[bill81vette]

Hi Gerry!!!!
I've never seen mine come on either...
but the tank never gets that low...
don't even know if it works....

 

[GerryLP]

Hi Gerry!!!!
I've never seen mine come on either...
but the tank never gets that low...
don't even know if it works....

Hey Billy,

Yeah. I know that almost no one lets their cars get that low, but on long trips, seeking a gas station every half tank does not work, specially going out west. lol

Anyway, it is a life saver having that light working. For standard L81 owners, it means another 30 - 36 miles to find that gas station on a cross country trip.

 

[GerryLP]

Update.

I purposely ran the Vette out of gas. Light did not come on. But at least I know where the 3 gallons is on my Vette gage. lol (i know, sounds idiotic).

I just hate the Vette not working as advertised. Mark, who sold me the module, sent me info in how to test the module. More to come.

GerryLP

 

[Yoda]

Gerry

If anyone will figure it out... my money is on YOU

I remember the time and effort you put into that "Holly Carb", oh and then the steering column

You da man!!

Bud

 

[GerryLP]

Gerry

If anyone will figure it out... my money is on YOU

I remember the time and effort you put into that "Holly Carb", oh and then the steering column

You da man!!

Bud

Thanks Bud,

Gail loves the warmer weather we've been getting. She is driving great! I need to take a drive somewhere.

GerryLP

 

[GerryLP]

Well folks,

i got the problem fixed. Finally!

you guys are going to love this lol.

It turns out, that when the module was installed upside down (albeit, it is round, it has a sticker with an arrow. The pointing arrow should be aimed at the top of the dash while being installed (not pointing down towards the floor). This was something I did without even noticing, and supposedly it blows one of the rectifiers.

So I returned it as instructed, and Mark fixed it. He also,"Gerry-rigged", a feature that if installed upside down, it will produce a low glow no matter how much fuel is in the tank, but at least it will protect the rectifier. LMAO!!!!

I guess you can say that I helped in its development ha,ha,ha

When I installed the repaired module, it was functioning normal. I then added 3 gallons of fuel exactly, and the gage reads between the red area and the 1/4 tank mark. And that's about 4-1/2 gallons (1-1/2 gallon in the tank + 3 gallons I added).

Mark is a 78 Corvette owner, and he makes these modules to help out. I paid $30 in eBay for it, and the pricing tells me that he is not out to gouge anyone for it. Plus his warranty has been Iron Clad. Should you guys need a los fuel warning module, please considera his module (I gain no compensation in any way, shape, or form. He did not refund my purchase. He did repair it and now works great).

http://www.ebay.com/itm/77-78-79-80-81-82-Corvette-Low-Fuel-Warning-Module-/121283042114

 

[22229stingray81]

My money was on a vacuum leak

Great job, Gerry. You realize you're slowly reverse engineering the L81, right?


-Tatortot