BajaNomad

Ever wonder how accurate your gas gauge is?

David K - 8-14-2010 at 10:25 AM

While mine has always seemed very close, I knew there was always more gas than shown on the gauge. I made close notes on my last tank, driving my typical work day (city and highway combined) and my truck was getting 16.5 mpg on this tank.

The Tacoma has a 21 gallon tank. So, every 1/4 tank is 5.25 gallons. However, the gauge does go a bit above the F line when topped off and goes below the E line, as well... without being empty.

I recorded the miles traveled for each 1/4 tank and later figured the gallons used based on the mileage that tank
delivered. I did fill up at 1/4 tank. But, I will continue making observations and run it to E when I can. I have before, and I have never put in more than 18.5 to 19 gallons of gas when the gauge was at E or below.

Full to 3/4 = 80 miles (4.8 gallons)
3/4 to 1/2 = 75 miles (4.6 gallons)
1/2 to 1/4 = 65 miles (3.9 gallons)
1/4 to 'E' = 85.5 miles (5.2 gallons)
From others and my past experiences, we have 2.5 gallons left when the needle is firmly over the 'E'...
So, 'E' to empty = 41 miles (2.5 gallons)

rocmoc - 8-14-2010 at 10:43 AM

A couple years back, 60 Minutes or one of those shows, did a story about gas gauges. They found they could normally travel 50 miles after the gauge showed empty. When they talked to the car manufactures, they found it was intentional as they found the customer blamed the manufacture if the gauge was accurate and they ran out of gas. Thus an unhappy owner / customer so they designed the gauges with a reserve that is not visible to the driver.

rocmoc n AZ/Baja

[Edited on 8-14-2010 by rocmoc]

woody with a view - 8-14-2010 at 10:47 AM

my tundra has 5 gallons left when the low fuel light comes on at "E"....

rocmoc - 8-14-2010 at 10:49 AM

German manufactured cars normally overstate the speed. I was told by a BMW dealer it was because the German Gov fined them if a car is manufactured and the speed was understated so they intentionally overstate. BMW is 4 mph overstated (know from experience & what the dealer said) & Mercedes is 2 or 3 mph (don't remember that one as it has been 10 years). This was the info in 1999.

rocmoc n AZ/Baja

Cypress - 8-14-2010 at 11:02 AM

Yea, coasted into Laramie, Wyoming on fumes once, good thing it was at the bottom of a long downhill grade. The 20 gal tank took 19+ gallons.:biggrin:

Mexitron - 8-14-2010 at 11:05 AM

For years my Chevy Silverado has had a fuel gauge that works to about 1/2 tank or so...then it either flips to empty or full and usually back and forth. So I have to remember to reset my trip odometer to know how much fuel is left. But before it stopped working the measurements were like yours David---it tended to drop fast between a half and a quarter tank. And I'm glad the manufacturers give us extra cushion at the bottom!

David K - 8-14-2010 at 11:13 AM

Quote:
Originally posted by woody with a view
my tundra has 5 gallons left when the low fuel light comes on at "E"....


Interesting... my Tacoma low fuel light comes on above the E line... at about 1/8 tank point, or just below.

If I pop into a station when the light comes on, I usually can put close to 17 gallons in (meaning there are still 4+ gallons left).

So, 7.7 gallons at the 1/4 line, 4 gallons at the warning light point, 2.5 gallons on the E line.

durrelllrobert - 8-14-2010 at 11:17 AM

When the 33 gal tank on my (6,800 lb) Yukon is topped off I can drive from Ensenada to US border (end of waiting line) and it still shows F. The next 3/4s go much faster but I just drove from El Paso TX to Ensenada and got 18.7 MPG with "traction control" shut off. With it on I ony get arond 17 on highway (don't know why it makes a difference):?:

David K - 8-14-2010 at 11:27 AM

Quote:
Originally posted by durrelllrobert
When the 33 gal tank on my (6,800 lb) Yukon is topped off I can drive from Ensenada to US border (end of waiting line) and it still shows F. The next 3/4s go much faster but I just drove from El Paso TX to Ensenada and got 18.7 MPG with "traction control" shut off. With it on I ony get arond 17 on highway (don't know why it makes a difference):?:


As I have shown, each 1/4 tank on the gauge is a different amount of gallons in the tank.

When full, your gauge is above the full line, yes? So, you have that plus the distance from the full line to the 3/4 line. Just like the last 1/4 tank to empty (true empty)...

I don't know what Traction Control a Chevy Yukon has, but in the Tacoma it is an electronic sensor limited slip using the brake system (and regulates engine output in 2WD, but not in 4WD).

So, we are normally open differentials until the wheel slip sensors detect slippage. If anything, by taking torque/ power away from a slipping tire and transfering it to a traction tire, you are using fuel more efficiently.

BMG - 8-14-2010 at 11:27 AM

I used to drive a diesel E350 van for business. Once I put the 'green handle' diesel spout in the filler tube and left it there until it clicked off. Then I realized that it just didn't smell right. I had filled the tank with unleaded.

I was able to push the van down a slight incline and get it out of the way and found a guy who brought some empty cans out to the station to drain the tank. The owners manual said the tank held 30 gallons which always seemed right. Whenever it was on empty, it would take 28-29 gallons.

Anyway, the guy had empty 5 gallon containers and filled 8 of them while I watched.

My lessons that day:

1. Pay attention.
2. The owners manual was off by a bit.
3. I had more reserve fuel than I thought.
4. Buying gas, paying to have it drained, and then buying diesel gets expensive.

BajaBruno - 8-14-2010 at 01:11 PM

If gas fuel-injected engines are like diesel, I would be careful not to run out of fuel. Bleeding a diesel injector system is a serious pain in the arse.

Cypress - 8-14-2010 at 01:19 PM

BajaBruno, Have done it. Not fun.

MitchMan - 8-14-2010 at 03:33 PM

I've had a gazillion cars of many makes and sizes - all gas guages were incorrect.

I seem to remember that I had a VW bug that didn't have a gas guage but had a lever to the left of the clutch (or someplace) that when you flipped the lever after you started to sputter from almost running out of gas, you got about a gallon or so more gas, then that was it. Also, it didn't have a tachometer. There was something appealing and easy about that simplicity.

[Edited on 8-14-2010 by MitchMan]

surfer jim - 8-14-2010 at 03:51 PM

I was thinking about that...remember some car with a lever for reserve.....yup...the old vw's.

Timo1 - 8-14-2010 at 04:22 PM

You guys must be REALLY bored
Let's talk Baja

monoloco - 8-14-2010 at 05:22 PM

When in Baja the Pemex regularly puts in more fuel than the capacity of my tank. :?:

capt. mike - 8-15-2010 at 07:26 AM

flying over to san diego from phx thursday. sometimes my right aux tank gauge gets stuck until some sloshing loosens the float to the sender.
well you never actually trust gauges anyway but for quick look against the true gauge which is power and time converted to gallons or pounds used.
anyway it showed about 1/2 full so i kept running off it assuming it had 30 min more go juice.
so droning along 10 east of yuma listening to comm chatter all of a sudden she powers off to 1000 rpms and it goes quiet which immediately wakes sleeping co-pilot [no, i didn't kidnap roger's lady!!]
a simple switch to the other of 4 tanks and she revs back to full power.

i normally don't let that happen. but like i said you never trust the gas gauge in a plane built in 1961.
hahaha.

mtgoat666 - 8-15-2010 at 07:46 AM

Quote:
Originally posted by David K
Ever wonder how accurate your gas gauge is


no.

woody with a view - 8-15-2010 at 08:58 AM

my tundra occassionally will slowly fall from full to empty in a matter of 3-5 miles. the first time it happened north of ensenada at night. FREAKED me out. i thought i had a leak somewhere. turns out it is a common gremlin for this era tundra.

i also go by mileage.