Testing Low Fuel Warning Light

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pantah
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Testing Low Fuel Warning Light

Post by pantah »

I have an idea. Rather than running the fuel tank way low can I jumper the sender unit from the top of the gas tank to at least test that the wiring and light works. If so what contacts do I jumper?

Also a question: at what point on the fuel guage does your light come on? I have run below E on the gauge but have never seen my light come on.
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Neu
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Re: Testing Low Fuel Warning Light

Post by Neu »

i dont have a low fuel light, and I know most dont.

YOu may not have one.
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ARCHINSTL
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Re: Testing Low Fuel Warning Light

Post by ARCHINSTL »

Dunno about DLXs, but SR5s have one (my '83 had one, as does my '86) - not that it works that well - sometimes I have 4+ gallons left out of a 13-gallon tank...
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Neu
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Re: Testing Low Fuel Warning Light

Post by Neu »

wow..i completely forgot that I actually do have the low fuel light.

lol, especially since for a while i spent so much time with it on.

Yeh, they are terribly inaccurate, the entire gauge is terrible actually.
terkill
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Re: Testing Low Fuel Warning Light

Post by terkill »

I have one and mines an 87 DLX
Ive gone 65 miles on the light. and still wasn't on fumes...
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Neu
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Re: Testing Low Fuel Warning Light

Post by Neu »

so this is what i'd usually do, i'd consider myself "close to empty" when i could see space between the needle, and the BOTTOM of the low/empty white line.
Highlander
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Re: Testing Low Fuel Warning Light

Post by Highlander »

The FSM does have a section on testing the low fuel light (Page BE-26)- It's in the section that describes the level sensor check out. It does require removing the sensor from the car, but it'll at least tell you if it functions or not-I have three that work and one that doesn't. The sensor is basically a resistance checker- if there is fuel contacting the end of the sensor, then the resistance is lower. when the fuel level drops past the end of the sensor, the resistance rises, the check out tells you to use water instead of gas (d'oh! :shock: ). Mine go on when I have about 1 gallon left in the tank (FWIW)
'83 SR5-299K, -tRusty!
'85 SR5-265K--GOLD
'85 SR5-285K-- GOLD-New engine!
'85 SR5-238K -- Teal-Killed by a DD
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pantah
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Re: Testing Low Fuel Warning Light

Post by pantah »

I checked the manual and it seems to me rather than pulling the sender unit all the way out, all I have to do is turn the ignition on pull the sender up so the sensor is above the fuel level in the tank and see if the low fuel light comes on. No need to test with it fully removed. Any problems with this? Will I blow myself up? Is this sender unit hard to get to?

Also still need more feedback of where on the fuel guage the needle is when the low fuel light comes on.

Thanks
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Neu
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Re: Testing Low Fuel Warning Light

Post by Neu »

Here, i'll try to type the way it comes on for me

----Full
---
--
-
------Half
-
--Comes on here sometimes, or the one below it.
---
----Empty
- (Needle goes below empty)

That' just mine though, it is a weird fuel gauge. It can come on REALLY early, and sometimes it'll go off after it comes on for a day or so.
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Re: Testing Low Fuel Warning Light

Post by Highlander »

Pantah- No worries about blowing yourself up unless you're smoking or have an open flame near the tank when you do it. You're right, it's easy to check as you said. Get a good phillips screwdriver (#1 & #2 is nice),Open the rear hatch, roll back the carpet on the passenger's side. The sensor is under a rubber cover type thing with a wire coming out of it. remove the 3-4 screws holding it down, slide the cover plate you just removed up the wire, there are 4-5 screws holding the sensor in. Clean around the top of the sensor (so you don't drop dirt into your fuel system) and mark the position (rotationally) for reassembly, remove the screws, pry the sensor up to release the gasket. Ease the sensor out, it has a bent arm on it- don't bend it differently, it'll work funny :wink: . Now with the rear seat down, and the ignition ON, you can see if the light comes on when you lift it out. One last caution- don't leave your ignition ON for very long without the engine running, you could burn out or damage your ignition exciter. Good Luck!
'83 SR5-299K, -tRusty!
'85 SR5-265K--GOLD
'85 SR5-285K-- GOLD-New engine!
'85 SR5-238K -- Teal-Killed by a DD
'58 and '62 Austin-Healey Sprites
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Re: Testing Low Fuel Warning Light

Post by takza »

There was a sort of write up on this? Just do it outside and when the tank is near to empty?
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Highlander
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Re: Testing Low Fuel Warning Light

Post by Highlander »

That was the write-up; I did it when I swapped the level sensors over from the wrecked '83. You can do it with the tank near full,it might help to be able to see the fuel level and when the sensor is in the fluid or out. I did it outside, 'cause that's where the wrecked one resides. ---Should it get posted under the Repair Guides?
'83 SR5-299K, -tRusty!
'85 SR5-265K--GOLD
'85 SR5-285K-- GOLD-New engine!
'85 SR5-238K -- Teal-Killed by a DD
'58 and '62 Austin-Healey Sprites
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skyerunner
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Re: Testing Low Fuel Warning Light

Post by skyerunner »

Neu - mine does the same thing.
I fill up and it goes all the way up. After driving for a bit it goes to empty. Then, somewhere around 1/4 tank it comes back up and then works its way down. I usually just reset the odo so I know how far I can get on a tank, but is there an easy fix for this?
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Highlander
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Re: Testing Low Fuel Warning Light

Post by Highlander »

Short answer- Not a reliable one- My '83s have great feul gages (even if the low level light doesn't work) My '85s are untrustworthy (though the low fuel lights work great). Skyerunner-PM me, I drive through Boulder twice daily.
'83 SR5-299K, -tRusty!
'85 SR5-265K--GOLD
'85 SR5-285K-- GOLD-New engine!
'85 SR5-238K -- Teal-Killed by a DD
'58 and '62 Austin-Healey Sprites
hberdan
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Re: Testing Low Fuel Warning Light

Post by hberdan »

Hey! I'm also in Boulder! Well, almost.
Anyway, I've had/have 3 Tercel wagons, and only one of them had a reliable fuel gauge, an 86 SR5. On the others, I've just reset the trip meter with every fill up and estimated mileage that way. It's a pain sometimes, since I have to always top off the tank when I refuel. But it's remarkably accurate, if i keep track of the average mpg.
As others mentioned, the gauge needle goes up when the tank fills, then drops to zero within a few driving miles--but climbs back to a quarter tank when the fuel is near that level--then the low fuel light comes on when theres probably 3 gallons left in the tank.
If I was industrious I'd change that sensor in the tank, but don't want to spend the money on the part, what are they now, over $70? You can buy a lot of Avery's at Liquormart for that kinda dough. I like that Out-of-Bounds Stout myself.
Last edited by hberdan on Thu Oct 08, 2009 7:57 pm, edited 2 times in total.
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