@sgtrock21 On my F150 the pump does shut off in the empty tank when you switch it.
“It’s a guy thing” is one answer to why we don’t like to fill up more times than absolutely necessary. And no, we don’t like to ask for directions, either . . . !
I recall reading in a Road & Track piece about an old MG of one kind or another, whose gas gauge would have made a great accelerometer: the needle gyrated wildly with each start-up or change in velocity.
While auto gas gauges are notoriously inaccurate, one thing many seem to have in common is that the true half-full point is indicated on the gauge at about the 1/3-empty mark (if there were such a mark on the dial). This is either laziness in the engineering department, or a ruse directly connected to the sales department: one’s first ride in the new car is accompanied by amazement at the mileage one is getting ! I know that’s what I thought, in my new '88 Civic Wagon – which I still happily own.
4th gen Civics were notorious for that. Mine would go 250 miles before hit the middle of the gauge, then would fall off a cliff. They seem to have changed, though - my 07 TL’s gauge starts dipping within a few miles of the gas station and declines steadily from then on.
I could compensate for my '95 Suburban’s gauge by assuming 1/5 of the tank was above the “F” mark, so each “quarter” of the tank was actually one-fifth. So I had about 40% left when it read half full.
Thanks, shadowfax – I’m glad to hear they’ve improved that aspect of vehicle reliability !
My mechanic, Pat’s Garage in San Francisco, told me to watch out for repeatedly running low on fuel, for the reasons mentioned above: the fuel is the pump’s lubrication. It can’t be cheap to have that pump replaced – I would think.
AND its coolant!
This is due to several factors-
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the gauge is not meant to be a laboratory instrument. It’s a cost versus benefit tradeoff. Note how the fuel sender works- it follows an ARC.
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Being inherently non-linear, they normally choose to put the best resolution at the BOTTOM of the scale where it adds value to the user.
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The tank is not symmetrical, they have very “organic” shapes to conform to the space available. This makes them non-linear as well regarding capacity variations compared to depth.
Could they design a system that was linear and more accurate? Of course. But if you knew the costs, I’ll bet no one would be willing to pay the additional costs. In this case, its GE (good enough).
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Right on ! And thanks . . .
S
I’ve got to go to the library and I’m just a little over a half tank, so my question is should I fill up before or after going to the library? It’s about 5 miles.
That depend’s is little over half full or a little under half empty.
I was a little concerned but I waited until my way home.
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Occasionally I will be traveling some interstate where it’s nice to know if I can reach my destination without running out of gas. That’s where having done a previous “capacity test” comes in handy.
Reminded me of the gas shortage days when you had to be concerned about getting gas along the way so you could get home. In laws lived 200 miles away and no way I could go 400 miles in my Olds and still get to work the next day without filling up. I’d have to be very careful to fill up where I could and back then I had two 10 gallon cans of gas in the garage for the old even/odd days.
That’s where having filled the tank when it reached the half mark comes in handy.
There is absolutely no advantage to allowing your tank to get so low that you have to have done a “capacity test” to feel confident that you’ll make it to your destinations. There’s only risk.
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TSM:
I do agree with you that many people’s style is to fill their tanks when they hit the half-way mark. I’m in the camp of those who prefer to stop for gas less often.
Either way, the pros and cons of each approach are small and in the noise level. It is just a personal preference.
You can calculate the cost of always carrying around a half tank of gas. Actually an extra 1/4 tank† or about 4 gallons, about 25 pounds.
According to one online source, that amounts to about $8 per year.
† If you fill up at half tank, your average load is 3/4 tank.
If you fill up at close to empty, your average load is 1/2 tank. Diff is 1/4 tank.
Just saying last year we were heading to New York from Minnesota and when we hit Ohio on the turnpike we were detoured and the road was closed. No police, detour signs or anything and just ushered off the turnpike due to a bad accident 100 miles away. So for the next three hours we were in 5-10 miles per hour backed up traffic on two lane roads. Folks there were no gas stations let alone men’s rooms or cafes. You just crawled along with the other thousands of cars and semis. Had it not been for our navi system I finally just broke ranks going south somewhere. I’m lucky I had 3/4 tank when it all started or I might still be there. I’ve been in some major traffic situations and the point is it can happen anywhere at any time without warning. Sometimes you can find a way around but sometimes not and you just have to suffer through it.
Like the other post where the OP obsessed over why the labor charge was $29.99 and not $30
I regularly go 550 miles on a trip before stopping with my Camry, I see no reason to add an extra stop every day.
Hmmmm… I wonder of those of us who owned cars during the oil embargo of '73 are more prone to not let our tanks run low?
Or perhaps those of us who were stuck in major blizzards, like the “great blizzard of '78” (people died in that one while stranded on the I-90 highway)?