I've got a '97 Accord and i've just been noticing a few things about the cars fuel economy. This has brought me to two questions

In the summer time, my car seems to consume more fuel even though my daily driving patterns haven't drastically changed. Granted, i drive a little less while school is in session, but not enough to have affected fuel economy too much. Has this happened to anyone? Because usually my trip odo. said about 150 miles by the time i got to a half tank, and i just crossed 200 the other day at half way. I don't often change my pace drastically either. I usually do 5-10 over the speed limit.

It also seems that after the half way mark, the car appears to consume more fuel quickly. Like, I just hit a half tank the other day, and today it's already between half and 1/4 left. Yesterday I drove from my house, to school, back to my house, to community college, and back home, for a grand total of maybe 25 miles. Today I drove from my house, to school, and back to my house, and it's getting closer to 1/4 already. So in short:

1) Does whether (outside temps) alter fuel consumption?
2) After half a tank is used up, do most cars (Accords in particular) consume more fuel at a faster rate

 

Question #1:
I usually experience the opposite because in cold weather I let my car sit and warm up for a few minutes so I burn more per miles driven. You "could" see better mileage under cooler temps because of a denser air/fuel mixture I suppose but I don't know if it would be that noticeable. Any of you engineering types wanna take a whack at it ?

Question #2:
Don't trust ANY gas gauge, the sending unit is basically a cheap rheostat and fluctuations like those you described are common on all makes.

 

1) Air temperature does affect fuel consumption. Although, in the opposite way you describe. In colder temp., an engine will need more fuel to compensate for the denser air charge. Also, the engine will need to do more work (meaning more fuel is required) to move the car through the colder, denser atmosphere. Also, the added resistance of a thicker engine lubrication will call upon the engine to do more work. Tires and cold weather also play a part in this. In warmer weather, the air is less dense, so the opposite of all the above is true. The reason many people see more fuel consumption in the summer is because of one thing, the luxury of air conditioning.

2)I have also noticed that after 1/2 tank my car seems to drink more gasoline. I can usually go for about 4-5 days on the top half, but after half tank, it just seems to disappear. I cannot answer this question, though. Maybe someone else can.

 

carolinaACCORD, i have the same problem where it seems like your car is using more gas while under 1/2 mark on your gauge...i really think its just a faulty gauge, the 94-97 gauges are not accurate at all. for instance, when the needle is on "E", i go and put in gas and sometimes it will only fill up to 10 gallons. this is wrong because the accord fuel tank holds 17.

 

yeah, Razor and Hippie are probably right, seeing as how most stock gauges, on all cars, are off by at least a little.

 

I've noticed that too. I'll be close to "E" so I go fill up and It only puts in about 9.5 or 10 gallons. Maybe I should just start waiting until the fuel light comes up

 

You should not wait until the low fuel light comes on. It's better to keep a full tank than an empty one. When the fuel level goes down there is more water in the air that takes up the space and condenses into your fuel. Also the empty tank exposes the tank itself to air which oxidizes more to create little tiny bits of rust that can get into yout fuel system and cause problems. Also all of the dirt and sediment from the time the car was first filled up will be concentrated in that little bit of remaining fuel. This will evetually get sucked up into and clog your fuel
filter(s). Again, ot good for fuel flow. Many people never go below a 1/4 tank.

Also on the fuel guages, my theory is that the first half of the guage sorta repesents the first 3/4 of the tank and the last half represent the other 1/4. Think about it, from the car manufacturers point of view. Most peolpe fill up when they get to a quarter tank. So it they make the first half of the fuel guage repesent that first 3/4 of a tank many people will think that they are getting better mileage and going very far on a tank of gas because they have traveled so many miles on just a half tank of gas. Also the needle when full to the top goes above the FULL mark. Did you ever notice the needle doesn't move for a while when the tank is full? I'm just saying this is a theory. I think in Hondas this may be true but not to the extreme of 1/2 of the fuel guage repesenting the 3/4 of a tank. It may be more like 3/5 on the upper half of the guage and 2/5 lower half. I know for a fact this is true on some domestics. My mom a while back had a Cutlass Cierra and I drove it on a road trip with her and on the first tank we almost ran out of gas. I was monitoring the mileage on the tank (just to prove that her car had an ineffecient 6cyl with NO power). After the first half of the tank was gone she said we should stop and get gas. I said no because on the first half we went (#) of miles and then about an hour later we were almost running out of fuel. I was like WTF. It was in the mountains on I-80 heading to NY and there are very few gas stations open at 2AM. Anyway this sort of mileage was repeated throughout the trip on each tank of gas which lead me to my theory. Any ideas or comments?

 

Ive seen that sort of action on many cars, but honda isn't one of them. I get very even gas mileage by following the guage. I usually get around 420 - 440 miles from a tank, and around 105 - 110 from every quarter.

I'm not sure I buy the whole don't let it get empty theory. Stew has some very good points about the air in the tank, so I'll believe that stuff, but the picking up sediment I've got some Qs about. basically all your sediment is going to settle to the bottom of the tank, gravity takes care of that. fuel pump pick up is always at the same spot, and AFAIK thats at the bottom of the tank. So you are always going to pick up the sludge on the bottom of the tank anyway. if you have the sludge in the tank, you are going to pick it up no matter what. Thats what the fuel filter is for, and why it is a regular maintenence item, not a wait until it gets gummed up and restricts flow item.

Aren't most new fuel tanks lined with some sort of corrosion resistant material? I know some new cars have a plastic tank, so corrosion isn't really an issue with them.

 

Same here

 

WHen I first purchasd my car back in May you could almost bet money on 100-105 miles for every 1/4 on the guage. and consistently about 31mpg give or take. I would just know it was time to get some gas when I hit 400 miles (so I didnt go below3-4 gal in the tank. The way I figured it is that when it shows empty (no light though) you had abut 3-3 1/2 gal. in fact, at first I thought my fuel light was broken because it wouldnt come on ever, and I was worried about running out when I still had 3+ left.
Now though, it seems that my milage has dropped dramatically. like sometimes by 10 mpg! I dont drive it hard all the time or anything, its just a mystery. so like instead of a hundred out of the 14 mark on the tank, Ill have like 60 or something, it sucks.
and then Ill fill up 4 gal in disbelief, I dont think 15 mpg is a number that a stock 130hp accord 5speed should be getting.

I have been noticing it idles rougher than it used to. and its just about to hit the 120K mark exactly... ...the dealership sent me a paper for 5%off the 120K tune up which includes like oil change, valve adjustment, and other stuff... THink I should do it? I just changed the oil, mobile1 5w30 synthetic....hmmm

Im just wondering if I ahve f*#$'d my car up somehow...

cheers,
sohc

 

A tune up can do wonders for gas mileage, but don't get raped by the dealership. Do it yourself and save a ton of $$$ and learn about your car.

 

I've gotten pretty much even fuel consumption in my Hondas too. I was wondering if anyone else noticed this slightly or not on theirs. In my '87 Accord after the last quarter of a tank it would seem to go quicker but it may have just seemed like it because my fuel was running low. I know that this was the case on my Mom's old car (she has a wonderful Nissan Maxima now).

Edit: Was that 5% off the 60% markup? Like SP said save some money and DIY.


[Modified by Stew Pidasso, 12:17 PM 12/6/2002]

 

I was just joking/being sarcastic anyways. With my luck, the light would come on when i'm miles from a gas station

 

I'm thinking that my low fuel light doesn't work on my '87. I've gone way past "E". I feel like Kramer sometimes...

 

Well this is a thought, but on a lot of fuel tanks, the bottom section is tapered, usually on the front and back. So I guess this might cause that effect when it gets really low to this smaller section. What do you think?

 

Hmmm, that is definitely a possibility...

 

my gauge is kinda funky too.. when i fill up it doesnt go all the way past F and when it gets to zero the fuel light doesnt even come on.. i think i'm gonna get an external gauge and see how that works.

 

Modified by CardDealer at 4:10 PM 11/17/2006

 

It may be the angle that honda places their fuel tanks, cause my 90 accord, mothers 94 accord, brothers 89 prelude all do the same thing. when it comes to gas consumption after the halfway mark.

 

how big is the 98-02 I-4 gas tank? damn 420+ miles per tank is a lot. i know with my 4th genner (13-15 gallon tank i think) my best mileage has so far been only about 380-390 miles. also as it gets colder i make many many more miles per tank compared to the summerand i think i actually drive harder in the winter cuz i like that extra power in the cold. like 275 on the first half of my latest tank and the last half will probably get me close to 400 miles for the whole tank, but that's ALL highway miles. last summer i babied the thing to make only 350 and a single best of 380 and the fuel light had been on for at least 10 miles before i could fill again.


[Modified by YodiBrodi, 8:24 PM 12/6/2002]

 

also, dont forget, that in the summer, u more then likely use ur A/C. but i too have noticed that the first half of a tank, the needle goes down slowly, then after that, it just drops rapidly, go fill up, and its only like 13 gallons to fill, and i gotta 17 gallon tank....so...yea

 

6th gen tank is HUGE, 17.1 gallons. 420 is nowhere near empty. I've pushed it out past 460 a couple times when I needed to. the light comes on with about 3 gallons left, thats close to 100 miles on the highway. great car for a roadtrip gastank is bigger than my bladder

 

Yea, I think that might be it. I guess I just never realize that I turn on the A/C, but I do drive with the windows down

LoL, not in a bone stock '97 Accord!

 

It is unbelievable how much A/C will rob you from a good gas mileage. My best on a 5th gen VTEC auto without A/C during summer, 562 miles (and that was really the best with ideal conditions, and ideal way of driving), and with A/C, 481 miles.
This was stretched to the max. I drove until it stalled, I carried a 5 gallons in the trunk.

 

1) I misplaced my owners manual, does anyone know how many gallons are left in the 4th gen gas tank when the light comes on? Im at about 307 miles to the tank and it should be on with in 50 miles. This was with 4 nights (2 wed. and sat.'s) of racing too. Best evar was 372 to a tank. H22 may have something to do with that though

2) From what I remember the 4G tank is 17 gallons too. Can anyone reassure me of this please.