'01 XJ fuel reserve?

Anyone know how much fuel is left when the low fuel warning light comes on? Is it 3 gallons? Tank holds 20 gallons. Trying to judge gas mileage.

You can't judge by that -- not with any degree of accuracy.

I usually do another 30 miles once the light comes on (and stays on) in my '01... have done 35 without any sputtering. My guess is you could push 40-45 miles but I don't think I'll try it. When I did 35 miles, I was able to put a full 18+ gallons in the tank (anthough it is listed as a 20 gal. I don't think any XJer has ever been able to squeez that much gas in one). Average fill up for me is 16-17 gallons.

Do you guys notice that the fuel gauge acts a bit non-linear at the limits of the gauge or is it just me? The gauge seems to be really sensitive near full and empty, like it drops really quickly right after a fill up, then drops normally, then speeds up again near empty.

Mine is pretty inacurrate. I just rely on my tripodometer and my gas mileage indicator on my overhead console (which is actually dead on).

homeinvader said:

Anyone know how much fuel is left when the low fuel warning light comes on? Is it 3 gallons? Tank holds 20 gallons. Trying to judge gas mileage.

Click to expand...

My low fuel warning light comes on when I have 4 gallons left. How do I know? Because it takes exactly 16 gallons to fill up the tank again right to the brim of the filler pipe.

Gauge at 3/4 = 15.5 gallons left
Gauge at 1/2 = 11 gallons left
Gauge at 1/4 = 6 gallons left

I've driven up to 50 miles with the low fuel warning light on and still had about a gallon of fuel to spare.
Use the above gallons left figures only as a guide. To accurately calculate gas mileage you still need to fill the tank up to the brim, zero the tripmeter, run the tank low, fill it up again, and divide the no. of gallons used into the no. of miles recorded by the tripmeter to get mpg.

Owners manual for my 90 says that the low fuel indicator will appear when there is "approx. 2 gallons of fuel left".....

Mine is so old, I was shocked when it actually worked!

Thayer said:

Do you guys notice that the fuel gauge acts a bit non-linear at the limits of the gauge or is it just me? The gauge seems to be really sensitive near full and empty, like it drops really quickly right after a fill up, then drops normally, then speeds up again near empty.

Click to expand...

I believe that has to do with the geometry of the linkage. I had an escort that would stay above half for 200 miles of the tank, then when it hit half a tank on the guage it plummeted and was the last 100 miles of the tank. Nowhere near linear, but I grew accustomed to it. MY MJ seems pretty good though, I've yet to test the low fuel light though. I'm carrying a 3 gallon gas can in case it doesn't work

It depends, and each Jeep is going to be a little bit different. When my '01 was brand new the gas guage was almost perfectly accurate (that is, if it said 1/2 and I filled it up I would get just a bit less than 10 gallons into it). Over time it has gotten less accurate and now the gas guage reads lower than it really is. Likewise, the point where the light comes on has changed.

So, the bottom line is no one can tell you for sure how many gallons are left in YOUR Jeep when the light comes on. You just have to figure it out for yourself.

Oh yeah, and Eagle was right. This is all irrelevant to calculating gas mileage. If you want to know your gas mileage here's what you have to do:

Over a significant period of time--8 to 10 fill-ups at least--keep track of what your odometer mileage is and how many gallons you put into the tank each time you fill it up. When you begin doing this, be sure you start with a full tank. In fact, the very first time, it doesn't really matter if you note how many gallons you buy, you just need to know that at thus-and-such an odometer reading you started with a full tank. After that it doesn't matter if you fill it full every time or not, just keep track of how much gas you put into it and what the odometer says.

After 8 to 10 fill-ups, when you want to calculate your mileage, be sure to fill the tank full again. Now add up how many gallons you've put in it since you started tracking. Subtract the number of miles on the odometer now from the number of miles at the time you first started tracking. Divide that number of miles by the number of gallons. Voila! You now have your average gas mileage over that period of time.

Personally--I know, it's a little bit anal--I've written down the odometer mileage and the gallons added every single time I've filled up my Jeep, since the day I bought it back in early 2001. I know exactly what my gas mileage is, and how it has changed over time.

I believe there is another minor consideration.

My understanding is the breather pipe in the tank is designed to provide a bit of expansion for the gas. Point being, in most cases (or probably almost all cases) you don't have 20 gallons as a starting value. So not knowing your true starting value is going to make it very difficult to calculate your actual values at any given point.

Kent

TheNerd said:

I usually do another 30 miles once the light comes on (and stays on) in my '01... have done 35 without any sputtering. My guess is you could push 40-45 miles but I don't think I'll try it. When I did 35 miles, I was able to put a full 18+ gallons in the tank (anthough it is listed as a 20 gal. I don't think any XJer has ever been able to squeez that much gas in one). Average fill up for me is 16-17 gallons.

Click to expand...

I actually got 21 gallons in my tank once

Both my 97's show about 20 miles Distance To Emtpy (DTE) on the overhead console computer when the low fuel light comes on and the chime goes off. It's always consistant within a mile or two +/- but I've never run it dry to see if it was telling the truth.

My warning light (little orange LED) goes on when I have 1/4 tank which seems like 7 gallons, the gauge isin't accurate. The warning light goes off when I get to about 2 gallons and will sometimes come back on. I think I need a new sending unit. I'd love to install an actual inline fuel consumption meter like some boats have.

I used to work 37 miles from home. I would drive all the way home with the DTE reading 0 miles. Gas was cheaper at home versus work. Granted, a new fuel pump will eventually negate any cost savings. Luckily, mine won't burn out until I'm in the middle of the desert in July.