Fuel Tank Capacity - Low Fuel Light

[PyrPatriot]

ETA: got 20.5gal in with a normal fill-up when I was 5mi into the "Low" indicator coming on. Some encouragement got another half gal in.

The manual says the JT has a 22gal fuel tank. That checks out as I had 440mi on the Range estimate after the dealer filled it up (20mpg average)

The light is supposed to come on when there are 2gal left. That checks out as the light came on around the 44mi left on the Range estimate when I was about 20mpg.

I can't get the tank to fill back up to 22gal. I filled it up when it should have had a gallon and a half of fuel left. It only refilled 18.5 gallons. Adding any more caused some gas to spill (didn't look like it was overflow from the tank but rather a feature of the fuel nozzle)

I thought it may be the gas station, weird pumps or something. Drove around 80mi, that should be over 4 gal because now I was at 18mpg. When I went to fuel up, only 3gal was put in, and that was with me trying to add more fuel. By my calculations I should have needed 7gal. 18.5 from when I estimated having 1.5-2gal left in my tank due to the light going on. Driving around 80mi burning 4gal.

So 20gal to refill, less the 19 I put in, plus needing to refill 4 more gallons, means 20+4-19 = 5 gallons short in my tank right now. Or am I missing something?


Update 11/23/19
I had the opportunity to try and run the tank low and get a good estimate of mpgs. I left Louisville to Cincinnati with 111 miles on the tank left. The trip is 90 miles but because of a wrong turn it ended up being 100. At my destination the trip estimator said 23mi left in the tank. This was weird because the fuel pump light didnt go on, which it does when there are 2gal left in the tank. I was getting about 18mpg so at 23mi left I should only have had a little over a gallon of gas left. I decide to drive 13mi to the nearest Costco, as that is the gas I last filled up the tank with. About a mile from the pump my miles remaining drops from 20 (keep in mind it had showed 23mi remaining for 8 miles) to “Low”, which happens when there is 15mi left before empty. Of course this happens right as I get stuck in stop-and-go traffic at the end of a line to the last stop light. At the station I refill 20.75 gallons. It originally stopped filling at 20 even but by waiting about 15 seconds and starting again until automatic shutoff I got another quarter gallon in. No overflow. I then proceed to park about 100ft away and go get some food. I give it a good half hour before I am back to my car in the cold rain. I go to see if it will take anymore gas and another 1/4gal goes in. Looks like that “wait a 30 seconds and fill, repeat” trick doesnt work like some have said does on the JK.

So, we have an even 21 gallons. Right where it should have been. Looks like everything is in order. I reset trip/mpg stats and make it home. Mpg was just over 22 pure highway driving at or just below speed limit (lots of steep hills). Combined miles driven and miles remaining put me at 450 miles, which at 21gal x 22mpg gives 462, close enough

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[Murgatroid]

The manual says the JT has a 22gal fuel tank. That checks out as I had 440mi on the Range estimate after the dealer filled it up (20mpg average)

The light is supposed to come on when there are 2gal left. That checks out as the light came on around the 44mi left on the Range estimate when I was about 20mpg.

I can't get the tank to fill back up to 22gal. I filled it up when it should have had a gallon and a half of fuel left. It only refilled 18.5 gallons. Adding any more caused some gas to spill (didn't look like it was overflow from the tank but rather a feature of the fuel nozzle)

I thought it may be the gas station, weird pumps or something. Drove around 80mi, that should be over 4 gal because now I was at 18mpg. When I went to fuel up, only 3gal was put in, and that was with me trying to add more fuel. By my calculations I should have needed 7gal. 18.5 from when I estimated having 1.5-2gal left in my tank due to the light going on. Driving around 80mi burning 4gal.

So 20gal to refill, less the 19 I put in, plus needing to refill 4 more gallons, means 20+4-19 = 5 gallons short in my tank right now. Or am I missing something?

I think the light comes on at 19, at least from my experience. I have driven it to the point where I put a little over 21 in when I really pushed stopping no a trip, so I know it has to be at least a 22 gal tank.

 

[NaughtyGeek]

I filled up the other day shortly after the light cam on and also put in ~18.5 gallons.

 

[PyrPatriot]

Oh and I forgot to add, the Range changed repeatedly just before the light came on. It was at 45mi, then went up to 60 after I drove, stayed there after I drove 10mi, and eventually after about 20mi more of driving jumped down to 35mi and the light came on.

 

[Mr._Bill]

The manual says the JT has a 22gal fuel tank. That checks out as I had 440mi on the Range estimate after the dealer filled it up (20mpg average)

The light is supposed to come on when there are 2gal left. That checks out as the light came on around the 44mi left on the Range estimate when I was about 20mpg.

I can't get the tank to fill back up to 22gal. I filled it up when it should have had a gallon and a half of fuel left. It only refilled 18.5 gallons. Adding any more caused some gas to spill (didn't look like it was overflow from the tank but rather a feature of the fuel nozzle)

I thought it may be the gas station, weird pumps or something. Drove around 80mi, that should be over 4 gal because now I was at 18mpg. When I went to fuel up, only 3gal was put in, and that was with me trying to add more fuel. By my calculations I should have needed 7gal. 18.5 from when I estimated having 1.5-2gal left in my tank due to the light going on. Driving around 80mi burning 4gal.

So 20gal to refill, less the 19 I put in, plus needing to refill 4 more gallons, means 20+4-19 = 5 gallons short in my tank right now. Or am I missing something?

The fuel gauge is not that accurate, and is probably rigged to keep you from running out of gas. Trying to get a specific correlation between fuel indicator and actual gallons in the tank will be very difficult. I've run mine very low a couple times, but never got more than 18 gallons in it to get a full reading. My understanding is that running it low is hard on the fuel pump. I usually fill up when it gets down around half, and try to keep it above a quarter tank.

 

[PyrPatriot]

The fuel gauge is not that accurate, and is probably rigged to keep you from running out of gas. Trying to get a specific correlation between fuel indicator and actual gallons in the tank will be very difficult. I've run mine very low a couple times, but never got more than 18 gallons in it to get a full reading. My understanding is that running it low is hard on the fuel pump. I usually fill up when it gets down around half, and try to keep it above a quarter tank.

My concern is that at the dealer we left the lot with the indicator in the red. Like 1/2 gallon in tank. First fillup had tank showing 440 mile range, and it got at least 360 miles before I filled up with about a 1/4 tank left. My concern is that I like to know the range available. I may just see if a 5gal tank fits down the pipe after a full fillup

 

[Mr._Bill]

My concern is that at the dealer we left the lot with the indicator in the red. Like 1/2 gallon in tank. First fillup had tank showing 440 mile range, and it got at least 360 miles before I filled up with about a 1/4 tank left. My concern is that I like to know the range available. I may just see if a 5gal tank fits down the pipe after a full fillup

To get an accurate comparison, you would need to run it down into the red and then fill up. I've run it very low a couple times, but never down to a red indicator.

 

[Hootbro]

My concern is that at the dealer we left the lot with the indicator in the red. Like 1/2 gallon in tank. First fillup had tank showing 440 mile range, and it got at least 360 miles before I filled up with about a 1/4 tank left. My concern is that I like to know the range available. I may just see if a 5gal tank fits down the pipe after a full fillup

I would not recommend shoving more fuel down the fuel filler neck after the fuel pump cut off. Good way to flood and eventually destroy your EVAP canister and start getting EVAP codes.

 

[PyrPatriot]

I would not recommend shoving more fuel down the fuel filler neck after the fuel pump cut off. Good way to flood and eventually destroy your EVAP canister and start getting EVAP codes.

And that is why I love this place, keeps me from harming myself from ignorance

 

[TLife]

There's no room for extra fuel. The problem is that you're assuming the range estimate is an accurate measurement of exactly how much fuel is remaining. In reality they've made an attempt to idiot proof it, meaning that when the estimate ticks to 0 (or whatever the cutoff is before it just says low fuel) there's fuel left in the tank. In my JKU it's about 3 gallons, which is in line with what you're reporting.

 

[PyrPatriot]

For the JT there should be 2gal left when the light goes off. LOW FUEL shows when you are down to 10mi estimate.

Out of 22gal I expect to get 400 miles out of the tank before the light comes on.

 

[Hootbro]

Adjust your expectations then. People complain about the same thing on other vehicle makes and models and the only one time I have heard of a TSB fix was for the late model RAM trucks that used two different size tanks but used the same smaller fuel tank software for DTE on the larger fuel tank model that had people with over 7+ gallons remaining when the low fuel light came one.

Being that it comes on the conservative side of the range, it is a first world problem that is not going to get solved.

 

[PyrPatriot]

Updated OP. Got 21gal to go in, and based on estimated mpgs during a 100mi trip yielded what I consider an accurate estimate of miles in a tank displayed

 

[Mr._Bill]

Updated. Got 21gal to go in, and based on estimated mpgs during a 100mi trip yielded what I consider an accurate estimate of miles in a tank displayed

How empty did you have to go to get 21 gallons in? I went down to 1/16 full with an orange indicator, and it took 18.5 gallons to fill it up.

The range estimate has always seemed fairly accurate. The fuel indicator seems rigged to keep you from running the tank empty.

 

[PyrPatriot]

How empty did you have to go to get 21 gallons in? I went down to 1/16 full with an orange indicator, and it took 18.5 gallons to fill it up.

The range estimate has always seemed fairly accurate. The fuel indicator seems rigged to keep you from running the tank empty.

I went beyond the range estimate saying “Low”, which happens when there is 15mi left in the tank. Being in stop-and-go traffic for about 10 minutes for a quarter mile then driving another quarter mile to the station (which had a line), I actually turned on the Start/Stop feature. When I fill up around when the fuel light goes on I only ever fit 18.5gal, but the fuel light coming on means you SHOULD be able to get 20gal in

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