Anyone Else Have Thier Gas Gauge Accuracy Degrade?

[Spazdog]

I thought over the last few tanks my mpg had fallen off. I normally get 100 miles per 1/4 tank. Been getting significantly less but my mpg stays consistant.

It's always been accurate in the past. I have an 18 gallon tank. If I filled up with it indicating 1/2 tank I would put in 9 gallons + or - a little bit.

Tonight, I was indicating 1/4 tank. Should have been 13.5 gallons. It was 12. 12.06 to be precise.

I guess I shouldn't complain. A pessimistic gas gauge doesn't leave one stranded still indicating gas in the tank. But I never had a gas gauge that lost accuracy over time. Even my Firebird was consistant....once the gauge stopped moving. My car is coming up on 100,000 miles.

 

[HTSS_TR]

The fuel gauges in my cars are very consistent. I look at the fuel gauge just before I refuel, I estimated the amount needed and usually within 0.1-0.3 gallons of the actual amount when the pump stopped.

 

[Joseph_S37]

The fuel gauge in my car is consistent from fill up to fill up, but its not consistent across its range, the top half always lasts a large bit longer than the bottom half... but it's always been like that, always the same, so i can't say its changed as it has aged...

 

[JimPghPA]

Interesting story about gas gauge.

Years ago I had a 1979 Buick regal. The gauge would show 1/4 tank when it ran out of gas. It was real accurate, and I could judge it very well. One friday evening I was too busy to put gas in it but knew there is enough to make it to the gas station. About 5 AM my younger brother knocks on my bedroom door and wakes me out of a very sound sleep. I was so asleep that I could hardly think. He said his car would not start, and he needed to borrow mine. Then he asked me where the keys were. In my half awake state I told him where they were. He took the car, and about a half hour later I woke up and realized that that car did not have enough gas to get him very far, and the gauge would still show 1/4 tank when it was empty.

This was before everyone had cell phones. Needles to say he got stranded.

 

[Boomer]

I just received an extended warranty on the gas gauge for my 2007 Nissan Frontier. Seems they are having problems with the gauge sending unit in the tank dying out over time and due to the number of complaints, extended the warranty on this part.

 

[rslifkin]

Mine has the same issue as Camry_Frenzy, but in a significant way. When it hits empty, it's actually empty. 1/8 is about 4 gallons left. However, add 3 gallons, and it's at 3/8. Add 8 gallons and it's at 5/8. It's another 11 gallons to fill it from there. The half tank point is really around the 5/8 mark on the gauge.

At least the full and empty marks are still correct.

 

[The_Jeff]

When I ran out of gas in my cutlass ciera, the last 20 miles the gauge was higher than "E". IOW it dipped down then started climbing up!

There are two different styles of gas gauge sender; one has the resistance go up as fuel goes up and the other the reverse. As things age this would affect different cars differently. GMs seem to show "Full" 100 miles after fill-up. I know someone who turned a rental in 65 miles after filling up.

This was before they started demanding receipts from local gas stations.

 

[Benzadmiral]

Originally Posted By: Camry_Frenzy37
The fuel gauge in my car is consistent from fill up to fill up, but its not consistent across its range, the top half always lasts a large bit longer than the bottom half... but it's always been like that, always the same, so i can't say its changed as it has aged...

Same with the Buick Park Avenue. The first 100 miles after a fill-up, the needle doesn't move. Then it begins to accelerate, so that at the halfway mark it's pretty accurate, i.e., would take about 9 gallons to fill it.

After that the needle falls like a stunned condor. It'll be touching the little red zone for a while before the low fuel light comes on.

It's always been like that in the three years I've had the car, and I'm used to it now.

 

[crw]

Yes, in fact as an engineer who has first-hand insight into these things, the fact that the needle stays near "FULL" longer than it ought to... this is by design! The gas gauge could be much more accurate than it is, but these decisions are driven by marketing.

If your needle starts acting differently than before, maybe try using some fuel system cleaner.

 

[Norm Olt]

Anybody ever had a leaky float in a carb before?

You know: a carburator? (Hint, hint: it is how gas used to get from the tank to the engine...)

How's about a new "album"? A new "record"?

An "LP"? A "45"?

Cheers! to all, including those under 30, or so...

"Never trust anyone over 15!" Wild in the Streets, circa 1968

 

[opus1]

The Dakota has a 22-gallon tank, I've let the needle get low enough to trigger the "Low Fuel" light twice in the 9 years I've owned it and in both cases, put in about 16 gallons (apparently the Dakota's light is very pessimistic). Half a tank is about a 10-gallon fill-up, and has been since day one. May not be accurate according to the gauge, but it's consistent. The Malibu I used to have was also consistent after 11 years, a half-tank was about 6 gallons.

I had a '75 Impala with a gauge that would stay on "F" for 4-5 days and the drop like a rock.

 

[Spazdog]

Originally Posted By: Norm Olt
Anybody ever had a leaky float in a carb before?

You know: a carburator? (Hint, hint: it is how gas used to get from the tank to the engine...)

How's about a new "album"? A new "record"?

An "LP"? A "45"?

Cheers! to all, including those under 30, or so...

"Never trust anyone over 15!" Wild in the Streets, circa 1968

I watched John Carpenter's The Thing on Laserdisc. My friend's dad got rid of his Betamax for the LD player.

...money well spent.

But anyway, I've had inaccurate fuel gauges before. My '72 Mustang would read 1/8th tank when it was out. Sadly it took me two times to figure that out. My Kawasaki would read full until you had about 1.5 gallons (out of 4) then plummet. But they were fairly consistant.

 

[fdcg27]

I always use the trip odometer as the primary fuel remaining instrument.
In either Accord, in the worst case, you can always plan on 425 miles on a tank.
In the Subie, more like 360, while the BMW is good for 425 as well.
You can usually tell when you are doing unusally well on a tank by how many miles you have driven when the needle indicates half a tank, which I have found is always actually less than half the capacity of the tank.
On any car you drive on a regular basis, you should have a very good feel for how far you can trust a full tank.
Incidentally, I have run a car out of fuel twice in the past thirty years, my MGB once, and one of our old Civics.
I both cases, I ignored my own rule.
Wishin' and hopin' will not extend range.

 

[Eddie]

I have read that some after market gas additives will cause the degrdation and that Techron system cleaner will in some cases help. I really don't know personally but, maybe someone will chime in here.

 

[Benzadmiral]

I've run Techron through my cars' fuel system for years, once every few months or so. It's never changed the behavior of the gas gauge at all. As CRW said, the gauge is designed that way. You cruise happily, thinking you're getting astonishing mileage, right after a fill-up; and you'll gas up quickly as the needle plummets toward E, preventing you (if you have the IQ of a house plant) from running out of gas.

Both elements are intended to keep you from thinking badly of your car.

Come to think of it, I don't recall my '65 Mercury's gauge behaving quite like that. Was there a point where the manufacturers started doing this?

 

[citationxeleven]

In my Civic I used Techron and didn't see accuracy improve until I put it in with a fillup but didn't drive it for 2-3 days. After that it improved for about 4 months. Now it is retuning to how it was showing it is empty even though there is 3 to 4 gallons left in the tank.

 

[morris]

why do you cats run your thank of gas down to empty? i run it to 1/2 and fill up, why, incase something comes up where i have to keep driving more than i would have. just my idea.

 

[javacontour]

It's not that tanks are designed to not drop when they are full, it's just the way it works in a closed tank.

For a visual, take the top off your toilet tank and if you have a float in there notice that a good portion of the float is ABOVE the water level in the tank. When you fill your gas tank, you also cover the float. Imagine the toilet tank filled to the brim with water.

The float in the tank will not move until the level drops enough that the float is no longer submerged in fuel and can rise and fall with the level of the fuel in the tank.

So this isn't some design feature, but the nature of using a float to determine the remaining fuel in the tank.

 

[Scienceman]

I will say that gas guages I'm my 90s fords are noth the best.

 

[sciphi]

The gauge in the Buick is horribly inaccurate right now. It has an 18 gallon tank. It was showing half a tank consumed. When refilling, 3 clicks got 6 gallons in.

The electronic gas gauge in the ScanGauge II is far more accurate.