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Topic Review (Newest First)
06-21-2013 12:02 PM
Atthehop
Quote:
Originally Posted by flflash View Post
You know I have yet to find anyone who can put 19 gals of gas in one of these 19 gal tanks? I'm thinking seriously about running mine out of gas then towing it to the gas station and filling it up.

That and I have the most consistent Jeep I've ever seen, fill it go 250 miles ( low gas light comes on about 250 ) takes 15 gals to fill it up again. I,ve checked it 5 tanks in a row since I re-geared it ( went from 4.10's to 4.56's I have 33's and 4" lift ) solid 16.5 mpg since re-gear from a previous consistent 15mpg
Yes I installed the correct speedo gear also.
No one will ever be able to run a tank completely dry in any vehicle. If you plan to do what you indicate the only thing you will get is a tow bill. And who really cares how many gallons it takes to fill the tank, it's the miles per gallon that matters. If you are using the fuel gauge reading to calculate MPG then you need to learn how to do it properly.
06-21-2013 11:55 AM
dcarey
Quote:
Originally Posted by Holton345 View Post
From all I read the width does have an impact on MPG. (A wider tire can make things somewhat worse.) If my rims can take them I will be moving from 12.5" to 10.5" tires. But I do not think I can run the narrower ones on my rims, which are 15x10...
Well I had my 33x12.5 mounted on the jeep for a month and changed them over to the norrower 10.5 and I noticed the differance right off the 12.5 are heavier than the 10.5 and there is alot more road drag with them. I then changed back to the 12.5 and jeep was a pig on the road.
06-21-2013 09:26 AM
Holton345
Quote:
Originally Posted by OhSixTJ View Post

Yes. Amazon.com has them for around $15. Couple it with and android phone and the free torque app in the android market and you've got lots of info in your hands.
Great. Next on my list of online purchases... THANKS!
06-21-2013 09:25 AM
Holton345
Quote:
Originally Posted by Jerry Bransford View Post
I did mean it the other way Holten, that a 15x10 wheel is way too wide for a 10.5" wide tire. Thanks for catching that. I certainly wouldn't run anything narrower than a 12.5" tire on a 10" wheel, though a 15x8 wheel would be ideal for combined off-road and on-road use with a 12.5" wide tire.
Thanks. Well, I hate the mileage, but the wider tires ARE more fun! I'll cope with the issue. Maybe I will get 15x8 rims at some point, but my choice seems to have been made for me by the previous owner.

I appreciate your time, sir!
06-21-2013 12:31 AM
OhSixTJ
Quote:
Originally Posted by Holton345 View Post
It also reads, "Upgraded OBD II Connectors." Can I purchase a reader for this connection?
Yes. Amazon.com has them for around $15. Couple it with and android phone and the free torque app in the android market and you've got lots of info in your hands.
06-21-2013 12:23 AM
Jerry Bransford I did mean it the other way Holten, that a 15x10 wheel is way too wide for a 10.5" wide tire. Thanks for catching that. I certainly wouldn't run anything narrower than a 12.5" tire on a 10" wheel, though a 15x8 wheel would be ideal for combined off-road and on-road use with a 12.5" wide tire.
06-21-2013 12:05 AM
Holton345
Quote:
Originally Posted by Jerry Bransford View Post
A 10.5" wide tire would be way too wide for a 15x10 wheel. A 15x7 wheel would be optimal though a 15x8 is fine too. I won't even run a 10" wide wheel with 12.5" wide tires when they are aired down for offroading.
Did you mean the reverse? A 10.5" tire would be way too narrow for a 10" wide rim? That makes a lot more sense, especially when you go on to say that the narrower rims would be better.

I think I get you, though. My rims are stupid wide, thanks to the previous owner. I do not air down; not once in ten years. So that is not a real consideration for me.

So you are saying that with my very wide rims that I am pretty much stuck with 12.5" wide tires? I guess I need new rims. At least they are nice Mickey Thompsons; might be able to sell them and get some Cragar Soft 8s or the like...

So if I wanted to use 32x11.5 I ought to have 8" rims? And if I go with the narrow 33x10.5" tires I can use the same ones (accounting for backspacing and such, that is)?
06-20-2013 06:01 PM
Jerry Bransford A 10.5" wide tire would be way too wide for a 15x10 wheel. A 15x7 wheel would be optimal though a 15x8 is fine too. I won't even run a 10" wide wheel with 12.5" wide tires when they are aired down for offroading.
06-20-2013 05:53 PM
Holton345
Quote:
Originally Posted by dcarey View Post
33 x10.5 15"
From all I read the width does have an impact on MPG. (A wider tire can make things somewhat worse.) If my rims can take them I will be moving from 12.5" to 10.5" tires. But I do not think I can run the narrower ones on my rims, which are 15x10...
06-20-2013 04:44 PM
dcarey
Quote:
Originally Posted by Holton345 View Post
That is great mileage. How old is your Jeep? And what tires are you running?
I have a 2004 wrangler sport running 33 x10.5 15" rims. I like running the thinner tire as I have had the 33x12.5 on there and there is so much more drag that I can feel on the road. milage is all about how you drive it I live in Denver I get about 15 /16 going in the moutains.
06-20-2013 04:37 PM
crallscars My 97 doesn't have a 19 gallon tank, wish it did, wish I knew where one was.

Gas gauge, it's an indicator, it should read, yep lots of gas, some gas, getting low.

If my red light goes on, I had better have a gas station in sight because the gauge falls very very fast when the light is on, maybe good for 10 miles.

I do go 300 miles on a tank of fuel (small tank,) when I have the hard top on, but cant with the soft top or no top.

I have been told not to run the Jeep below a 1/4 tank, that the fuel will cool the pump.
Not sure if this is true or not, but I haven't run out of fuel since I started this.

I can easily do 20mpg with the hard top driving under 70 mph
06-20-2013 03:44 PM
Holton345
Quote:
Originally Posted by Theorist View Post
3.73 is one of the stock gear ratios. The on-off-on-off-on trick should work fine.

Okay, so my gearing (if it has not been changed) is not the mileage issue. Thanks for that chart, man!
06-20-2013 03:43 PM
Holton345
Quote:
Originally Posted by dcarey View Post
I have a 19 gal tank I can get between 17 and 19 MPG. I can get 300 out of a tank but it requires going below the red mark on the gauge. I checked how many gallions I fill up with when the Gas light comes on it is 5 gal left in the tank and about 250mi on the ODO.
When the gas light comes on I take note of the ODO. I then know I can go safely another 50 to 60 mi or so and have 2 gal reserve.
That is great mileage. How old is your Jeep? And what tires are you running?
06-20-2013 03:28 PM
Theorist
Quote:
Originally Posted by Holton345 View Post
So obviously my gauge is wonky. I will "learn" the vehicle as I drive it. And I will give it a tune up to see if the MPG comes up a bit. I am certain the tires are causing some of the low MPG as they are really wide (a no-go for good mileage) and worn nearly bald in the center with next to no lugs left on the surface. After tires I will measure MPG again as carefully as I can for several tanks and report back about what is going on. Should I bump this thread or start a new one? Most of the places I surf encourage longterm bumps for historical reasons. This place seems to frown on bumping. How weird...

My build sheet says "3.73 rear axle" and I do not know whether it has been re-geared. How can I check the gearing? Would this affect the MPG? It has mucho pick up from a dead stop.

It also reads, "Upgraded OBD II Connectors." Can I purchase a reader for this connection? Or will the old standby key on-off-on-off-on give me the code for the CEL?
3.73 is one of the stock gear ratios. The on-off-on-off-on trick should work fine.

06-20-2013 03:27 PM
Holton345
Quote:
Originally Posted by Theorist View Post
It sounded like you were implying that they refused to tell you what code they had read.
Ah, no. No actual refusal. He just said it was "probably bad gas." He said to fill it up and run it down and fill it again. That ought to take care of it.

To me is sounded like he was thinking it was old fuel. But I do not know. I see what you mean, though. If he had actually refused to tell me (had I asked for the code that it was throwing) I would have been pretty put off by that.

And he was correct in that it drove for 243 miles mostly at about 65 to 70 mph (actual, not what the speedo read, which is five lower). No light all the way home, with two times stopping and restarting, so that the computer had a chance to check things fresh each time. No light at all. Then this morning it was on again...
06-20-2013 03:26 PM
biggus35 Same problem here. I just ran my 2002 X as empty as I thought I could safely get away with. It only held 15.172 gallons. It was way in the red and the light had been on for 20+ miles.
06-20-2013 03:25 PM
Holton345 So obviously my gauge is wonky. I will "learn" the vehicle as I drive it. And I will give it a tune up to see if the MPG comes up a bit. I am certain the tires are causing some of the low MPG as they are really wide (a no-go for good mileage) and worn nearly bald in the center with next to no lugs left on the surface. After tires I will measure MPG again as carefully as I can for several tanks and report back about what is going on. Should I bump this thread or start a new one? Most of the places I surf encourage longterm bumps for historical reasons. This place seems to frown on bumping. How weird...

My build sheet says "3.73 rear axle" and I do not know whether it has been re-geared. How can I check the gearing? Would this affect the MPG? It has mucho pick up from a dead stop.

It also reads, "Upgraded OBD II Connectors." Can I purchase a reader for this connection? Or will the old standby key on-off-on-off-on give me the code for the CEL?
06-20-2013 03:21 PM
dcarey
Quote:
Originally Posted by Holton345 View Post
I bought a 2003 Sport yesterday. It was five hours from my home, and in driving it back It seemed to only get 13 mpg. (It read about 5/8th empty when I bought it. It took 8 gallons to fill it from that mark. Drove about 240 - 250 miles. Stopped once to top up and filled it up when I got home. I used a total of 18 gallons on the trip of 250 miles.)

This gas gauge drops quickly. On my old SE 2.4L I would have about 35 miles on the tank before the needle would even move, averaging about 70 miles per quarter tank. On this Sport it read nearly a 1/4 tank down at 40 miles into my trip home. Then the needle hung there for a while. At just below 3/4 of a tank (according to the gauge) it took 11.5 gallons of gas until the pump cut off.

Doesn't the Sport have a 19 gallon tank in all cases? Even my SE with its 15 gallon tank *actually* has the 19 gallon one with an alteration to the fill tube so that it cuts off at 15 (by design, but actually mine allows filling up to 17 gallons). If the gauge on this Sport is correct then my tank is full at 15 gallons. This cannot be correct...

Could the previous owner have had the sending unit replaced and an SE on have been put in by mistake? Or is the gauge really as bas as people say? How do I test it? I have heard driving a modern car (late 1990s or newer) until it runs dry and dies is really bad for the injectors.

(I was thinking of carrying a 5 gal jerry can and driving it until it ran out to see ho the gauge reads and then see how much it takes to fill it up. I would have to do this when it is very nearly empty and just drive around very close to the gas station, fill it with the jerry can and add 5 gallons to the total I put in at the pump. Again, bad idea???)

I am running exceedingly worn 33x12.5x15 tires and know this is part of the MPG issue. That will be corrected soon enough. But the gauge worries me some.
I have a 19 gal tank I can get between 17 and 19 MPG. I can get 300 out of a tank but it requires going below the red mark on the gauge. I checked how many gallions I fill up with when the Gas light comes on it is 5 gal left in the tank and about 250mi on the ODO.
When the gas light comes on I take note of the ODO. I then know I can go safely another 50 to 60 mi or so and have 2 gal reserve.
06-20-2013 03:18 PM
Theorist
Quote:
Originally Posted by Holton345 View Post
Why? I did not buy it from them and they knew I was about to drive it five hours. They had zero reason to not try to make additional money from me on the spot to fix my issue. Instead they let me go and were nice enough to not charge me for the reading. As they said, after my fill up I drove close to 250 miles and it stayed off. So why the suspicion?
It sounded like you were implying that they refused to tell you what code they had read.
06-20-2013 03:16 PM
Holton345
Quote:
Originally Posted by Theorist View Post
Huge red flag...
Why? I did not buy it from them and they knew I was about to drive it five hours. They had zero reason to not try to make additional money from me on the spot to fix my issue. Instead they let me go and were nice enough to not charge me for the reading. As they said, after my fill up I drove close to 250 miles and it stayed off. So why the suspicion?
06-20-2013 03:13 PM
Holton345
Quote:
Originally Posted by Dextreme View Post
Add the % back in for the 33's as I suggested above...if your speedo gear is calibrated for you oem size tires.
I did not use the trip odo for the final measurement. It is 22 miles off from reality. For the mileage calculation I used the miles as calculated from address to address by Google Maps. I actually traveled 243 miles and actually used 17.5 gallons of gas. The tires have nothing to do that that. They DO make the trip (and regular) odo read wrong and give me an incorrect speed. I will change the gear soon. I have done this before and just need to find out which part number I need to pick up at my local dealership.)

But actual miles and actual gallon amounts are what I need. And that is what I used. Again, they came out to almost 13.9, which tells me that the very worn 33x12.5 tires are sucking the gas due to the width and the weight. That, too, will be sorted soon. I just have having to wait for TireRack.com to ship me stuff. I am impatient! HA!

I have had a CEL twice in two days. I will look to that to see if my mileage problems are in the engine. I hope the better tires will help but know that at 33" probably my mileage will always be mediocre.

But the dang gas gauge inaccuracy was alarming since my SE's gauge is so much more accurate. This Sport's gauge was sort of frightening out in the middle of nowhere late at night in the Mississippi Delta on HWY 1 and HWY 61. There is no place to stop out there if you run out of gas, and the stations can be 50 miles apart or more in long stretches of the route I took. At least I know now that there is a 19 gallon capacity despite the gauge indicating that there is only 16...
06-20-2013 03:07 PM
Theorist
Quote:
Originally Posted by Holton345 View Post
They did not tell me what they found
Huge red flag...
06-20-2013 03:03 PM
Holton345 Okay, according to Google maps, from the gas station in Hot Springs where I filled up before my trip home to the gas station where I filled up when I got home is 243 miles. The Jeep's trip odo reads 221.

It is also reading exactly 5 mph slower than my wife's 2010 Honda Accord. Do newer Accords still have the mph set to read off by 3 as in the past? I have not heard of this changing, but it seems with so many people using GPS to figure MPH that they would give up on this practice.

So we have a difference of 22 miles on the Jeep from the Honda and Google, reading short. It moves faster than indicated.

I suspect the speedo gear was never chanced after the 33s were put on.

I will do that soon.

The MPG numbers are (more accurately) 243 miles using 17.5 gallons. I get about 13.9 — Still not so good.

Build sheet specifies that this has a 19 gallon tank. So roughly 16 show up in the range of the gauge. I guess when it reads E I will have about three gallons left.

New issue: CEL

When I bought it the tank read more than 3/8 full (whatever that means) and before filling it, like 50 yards from the seller's place (and right after having had the inspection run) the CEL came on. Ugh! So we went back the the dealership and had them run the codes. They did not tell me what they found but said it was running lean. They asked whether I had just filled it up. I said no. They said it was probably a "bad gas issue" but never explained shat they meant by that. They reset it and told me to fill it up. It might come back on but probably not. I filled up and drove 243 miles home and it never came back on. I stopped twice on this trip for gas. The CEL never came back on.

This morning I started it cold and the CEL came on right away. X-[
06-20-2013 02:53 PM
flflash You know I have yet to find anyone who can put 19 gals of gas in one of these 19 gal tanks? I'm thinking seriously about running mine out of gas then towing it to the gas station and filling it up.

That and I have the most consistent Jeep I've ever seen, fill it go 250 miles ( low gas light comes on about 250 ) takes 15 gals to fill it up again. I,ve checked it 5 tanks in a row since I re-geared it ( went from 4.10's to 4.56's I have 33's and 4" lift ) solid 16.5 mpg since re-gear from a previous consistent 15mpg
Yes I installed the correct speedo gear also.
06-20-2013 02:34 PM
Dextreme
Quote:
Originally Posted by Holton345 View Post
That is pretty much what I did, as per paragraph one of my post. I filled it. I zeroed out the trip odo and when I got home I added up the number of gallons I used and divided the miles driven by the gallons used and got 13.
Add the % back in for the 33's as I suggested above...if your speedo gear is calibrated for you oem size tires.
06-20-2013 02:33 PM
Holton345
Quote:
Originally Posted by speedyrev View Post
The first thing I would do is correctly check your mpg.

1. Fill tank
2. Set trip Odometer to 0
3. Run till fuel gauge is near empty
4. Fill up and make note of gallons
5. Divide #of miles on odometer in step 4 / # of gallons in step 4.

*edit - you can get the build sheet from Jeep that will tell you what gas tank you have.
That is pretty much what I did, as per paragraph one of my post. I filled it. I zeroed out the trip odo and when I got home I added up the number of gallons I used and divided the miles driven by the gallons used and got 13.
06-20-2013 02:26 PM
Jerry Bransford X2 on the info in post #2 above. No gas gauge is even close to being accurate enough for mpg calculations, the only accurate way to calculate mpg is as above.
06-20-2013 02:23 PM
Dextreme Basically with a 19 gallon tank...fill, go about 230-250miles, repeat. It is what it is.

Quote:
It seemed to only get 13 mpg.
Remember that you have to add back in the % increase of the 33's over stock...probably closer to 15mpg corrected.
06-20-2013 02:19 PM
speedyrev The first thing I would do is correctly check your mpg.

1. Fill tank
2. Set trip Odometer to 0
3. Run till fuel gauge is near empty
4. Fill up and make note of gallons
5. Divide #of miles on odometer in step 4 / # of gallons in step 4.

*edit - you can get the build sheet from Jeep that will tell you what gas tank you have.
06-20-2013 02:09 PM
Holton345
MPG/Gas Gauge Accuracy

I bought a 2003 Sport yesterday. It was five hours from my home, and in driving it back It seemed to only get 13 mpg. (It read about 5/8th empty when I bought it. It took 8 gallons to fill it from that mark. Drove about 240 - 250 miles. Stopped once to top up and filled it up when I got home. I used a total of 18 gallons on the trip of 250 miles.)

This gas gauge drops quickly. On my old SE 2.4L I would have about 35 miles on the tank before the needle would even move, averaging about 70 miles per quarter tank. On this Sport it read nearly a 1/4 tank down at 40 miles into my trip home. Then the needle hung there for a while. At just below 3/4 of a tank (according to the gauge) it took 11.5 gallons of gas until the pump cut off.

Doesn't the Sport have a 19 gallon tank in all cases? Even my SE with its 15 gallon tank *actually* has the 19 gallon one with an alteration to the fill tube so that it cuts off at 15 (by design, but actually mine allows filling up to 17 gallons). If the gauge on this Sport is correct then my tank is full at 15 gallons. This cannot be correct...

Could the previous owner have had the sending unit replaced and an SE on have been put in by mistake? Or is the gauge really as bas as people say? How do I test it? I have heard driving a modern car (late 1990s or newer) until it runs dry and dies is really bad for the injectors.

(I was thinking of carrying a 5 gal jerry can and driving it until it ran out to see ho the gauge reads and then see how much it takes to fill it up. I would have to do this when it is very nearly empty and just drive around very close to the gas station, fill it with the jerry can and add 5 gallons to the total I put in at the pump. Again, bad idea???)

I am running exceedingly worn 33x12.5x15 tires and know this is part of the MPG issue. That will be corrected soon enough. But the gauge worries me some.

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