Gas gauge acting funky
06-14-2006, 10:26 AM
#1
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Gas gauge acting funky
Just out of curiosity dose your gas gauge do this. When I drive the car my gauge seems to fluctuate a lot. When I start it it seems to drop half a tick to a full tick right away or with in a couple of minutes. As I drive it the gauge slowly comes back up. Every time I start it it dose the same thing, the gauge is always lower then when I turned it off. It seems even more pronounced at the last quarter of a tank. Anyone else get this?
Last edited by Raptor75; 06-14-2006 at 10:37 AM.
06-14-2006, 10:39 AM
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Originally Posted by Raptor75
Just out of curiosity dose your gas gauge do this. When I drive the car my gauge seems to fluctuate a lot. When I start it it seems to drop half a tick to a full tick right away or with in a couple of minutes. As I drive it the gauge slowly comes back up. Every time I start it it dose the same thing, the gauge is always lower then when I turned it off. It seems even more pronounced at the last quarter of a tank. Anyone else get this?
I don't think that is normal. Sounds like your sending unit, probably located in the fuel tank, is acting up.
06-14-2006, 10:44 AM
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I think everyones probably does this. The system is updated constantly and is always calculating the position the gas gauge should be at according to how your currently driving, i.e. speed, throttle psoistion, etc... I would think its normal. Correct me if Im wrong though.
06-14-2006, 11:01 AM
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Seeing that the RX has a saddle tank, which straddles the drive shaft there must be a pump that moves fuel from one side to the other. This could explain the wired movement. This is just speculation, anyone no the facts of this?
06-14-2006, 11:15 AM
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I am not 100% sure about the RX-8 tank configuration but I work for a Fuel Pump and Module Manufacturer and know of this same problem for other similar designs (saddle tank) were the gauge has "funny" readings. There is a venturi that transfers the gas from the "minor" side of the saddle tank to the side where the fuel pump is located. When the engine is tured off, some of the gas from the fuel pump side of the saddle tank flows back to the side without the fuel pump. This gas transfer (when the engine is off) causes incorrect fuel level reading for a short time when the engine is restarted. Our customer has installed a check valve in it's newer products to prevent this problem from happening. We don't make the fuel pump and module assembly for the RX-8 so I don't know the specifics of their system.
06-14-2006, 11:20 AM
#10
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Originally Posted by t-run/8
Yes. I get excited by noticing how many miles per tank I have then the excitement is shattered when it drops two or three ticks in a couple seconds.
You have no idea how often this happens to me.
"HOLY CRAP! I've driven 100 miles and it's at where I normally drive only 70 miles! This tank is gonna kick ***!"
two minutes later, the needle has dropped 2 ticks.
"Damn."
It happens the other way to me sometimes though. Like according to the gas gauge I've driven like 20 miles less than I normally do at that point, but give it a day or so and I'm back to normal. The gas gauge is not to be trusted.
For me, usually I go to quarter at 50-60. To half at 110-120. To 3/4 at around 200. To light going on at 230.
06-14-2006, 11:25 AM
#11
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Could be worse.. yanno if your low gas warning light didnt work properly at all.
I notice this happening every so often but as you and others stated its just the gauge adjusting itself. I had a Chevy W/T before this and that thing was yeah horrible, I never knew how much I had in the tank because a friend speculated that the floater or whateva was most likely messed up royaly. I'd fill the tank up, all 27 gallons of it and it would either be at Full or be about 1/8 the way past Full. I'd say keep a eye on it and if it annoys the hell out of you take it to Mazda and ask them to take a look at it.
I notice this happening every so often but as you and others stated its just the gauge adjusting itself. I had a Chevy W/T before this and that thing was yeah horrible, I never knew how much I had in the tank because a friend speculated that the floater or whateva was most likely messed up royaly. I'd fill the tank up, all 27 gallons of it and it would either be at Full or be about 1/8 the way past Full. I'd say keep a eye on it and if it annoys the hell out of you take it to Mazda and ask them to take a look at it.
06-14-2006, 12:01 PM
#13
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Originally Posted by baysj
It happens to me also, which is weird because I will be at just above 1/4 take for 40 miles
06-14-2006, 01:26 PM
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Originally Posted by spork
I'd laugh if I weren't crying.
You have no idea how often this happens to me.
"HOLY CRAP! I've driven 100 miles and it's at where I normally drive only 70 miles! This tank is gonna kick ***!"
two minutes later, the needle has dropped 2 ticks.
"Damn."
It happens the other way to me sometimes though. Like according to the gas gauge I've driven like 20 miles less than I normally do at that point, but give it a day or so and I'm back to normal. The gas gauge is not to be trusted.
For me, usually I go to quarter at 50-60. To half at 110-120. To 3/4 at around 200. To light going on at 230.
You have no idea how often this happens to me.
"HOLY CRAP! I've driven 100 miles and it's at where I normally drive only 70 miles! This tank is gonna kick ***!"
two minutes later, the needle has dropped 2 ticks.
"Damn."
It happens the other way to me sometimes though. Like according to the gas gauge I've driven like 20 miles less than I normally do at that point, but give it a day or so and I'm back to normal. The gas gauge is not to be trusted.
For me, usually I go to quarter at 50-60. To half at 110-120. To 3/4 at around 200. To light going on at 230.
to the poster: i dont think ive noticed anything as drastic as what your describing, just an overall "the needle isnt consistent" sort of thing.
06-14-2006, 01:41 PM
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I noticed slight fluctionations, but nothing to cause me concern.
The Chrysler mini-vans stay pegged a FULL for quite a while, then drop like a rock. I swear I've seen my wife's van reading nearly full with nearly 100 miles on the tank (it typically has a 360-mile range so that math doesn't work).
My F150 had dual tanks. One tank would read full forever and not move. The other worked the opposite: dropped from full to empty after just a few miles on that side.
Frankly, there's less variation in the gauge than I would expect from all my turning, accelerating, stopping and all the rolling hills in the area.
The Chrysler mini-vans stay pegged a FULL for quite a while, then drop like a rock. I swear I've seen my wife's van reading nearly full with nearly 100 miles on the tank (it typically has a 360-mile range so that math doesn't work).
My F150 had dual tanks. One tank would read full forever and not move. The other worked the opposite: dropped from full to empty after just a few miles on that side.
Frankly, there's less variation in the gauge than I would expect from all my turning, accelerating, stopping and all the rolling hills in the area.
06-14-2006, 01:44 PM
#19
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Well at least I'm not going crazy, glad to hear your all in the same boat. I also have felt the crushing pain of what appears to be great mileage disappearing in the final 1/4 thankful. Its like having a good looking girl slowly unbutton her sweater only to find out she is wearing a tee shirt ;-)
Last edited by Raptor75; 06-14-2006 at 01:48 PM.
06-14-2006, 02:15 PM
#21
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Originally Posted by spork
For me, usually I go to quarter at 50-60. To half at 110-120. To 3/4 at around 200. To light going on at 230.
06-14-2006, 02:15 PM
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Also, fuel expands a lot with heat. That will make the float change. Try putting gas in a red plastic gas can and set it in the sun. It will expand a lot. So driving, the exhaust will heat up the tank and the gas will expand.
Mike
Mike
06-14-2006, 02:28 PM
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I mainly notice that the gauge doesn't go down consistently for the readings so much. It's not that far off but doesnt' drop consistently. Starting at full, my has around 80 at the first 1/4 down mark. It has around 150-160 at the half, the next quarter shows up anywhere between 220-250. My light will come on around 290ish.
06-14-2006, 03:55 PM
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Originally Posted by agoodcave
Also, fuel expands a lot with heat. That will make the float change. Try putting gas in a red plastic gas can and set it in the sun. It will expand a lot. So driving, the exhaust will heat up the tank and the gas will expand.
Mike
Mike
So based on the feed back we now know the gas gauge is a little inaccurate and the heat from the exhaust further effects the accuracy by expanding the fuel during use which accounts for my gauge raising during use and falling considerably when the car is restarted the next morning or at the end of work. It would also explain why the readings fluctuate more when your down to a quarter of a tank, the gas expands even more because there is less of it absorbing the heat from the exhaust. Put the saddle tank into the equation and the mystery is solved.
Excellent, thanks for the input.
06-14-2006, 05:39 PM
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Originally Posted by RedLineShinka
I WISH... I get ~200mi off a gas tank, so it's 50mi at each major tick 'cept for the last 1/4 tank of gas is hillarious. I'm at like, 200 with just under a 1/4 left, then at 210 I'm on the light and at 220 (if I'm lucky) I'm below the red final tick.... it's hillarious how OFF it is on that last 1/4 tank.