The last time I checked it stock, I got about 400 miles, but that was with about 23 gallons in the tank

I'm quite sure I don't get that anymore. My rolling resistance is a lot higher and fuel delivery is more aggressive

 

You must have the vent tube mod, because stock capacity is 20 gallons.

 

Miles per tank? I just never really check it. But then my XJ is used like a tractor. At least 75% of my driving is done in 4WD and/or towing a trailer with ATV's or snowmobiles. I guess if I had to guess I'd be in the 250 range unloaded. But with a trailer, it's just not pretty.......

 

I see a huge difference between highway and mixed running around. Up near 25 Hwy, and right down around 14 with much dinking around. The lower figure comes up one MPG with premium, but I can't say for sure the difference on the Hwy. I'm working on it, suspecting possibly Renix with the knock sensor might, maybe, see better economy with mid grade, or premium.

 

I've noticed better economy with higher grades. Wasn't but maybe 1 or 2 mpg but was noticable.

 

The odd thing is I get 11-12 mpg around town but on the rare occasions that I do take a highway trip that almost doubles my mpg

 

My 88 is bone stock, save for bigger wheels (and corresponding higher gear ratio) and I get about 15-17 mpg driving like grandpa in the flat city of Phoenix.

The tanks are capable of holding 23 gallons, which would equal about 350 or so miles per tank. Some tanks have a restricting hose that will only let you fill it to about 13 gallons or 20 gallons, depending on what was paid for at the dealership. Lousy marketing ploys...

 

My understanding is that all of the tanks are actually the same size. The maximum capacity of a stock tank as it was delivered from the factory is 20.2 gallons.

The "13 gallon" tanks were the exact same size as the "20 gallon" tanks, but the vent tubes were positioned so that you could only put 13 gallons in them. That's your stupid marketing ploy, artificially restricting the capacity of the tank just to soak the buyer for more money. The "13 gallon" tanks sit 35% empty when they are "full," which is not only a waste of space but also increases the likelihood of condensation.

The "20 gallon" tanks came in two flavors, metal up to 1996 and plastic from 1997 on. Those of us with plastic tanks appear to be stuck with 20.2 gallons. When the tank is "full" at 20.2 gallons, there is still room at the top for three more gallons of fuel.

With the metal tanks, you can take advantage of this extra capacity by modifying the vent tube. Below is what it looks like, with pics stolen from that site. Stock:



Modified:



With that mod, you can keep filling the tank another three gallons until fuel enters the vent tube and causes the back pressure in the filler pipe to shut off the pump.

So, those of you saying you're pumping 23 gallons, at some point someone has probably modified your tank. The rest of us should not expect to be able to do that.

At some point in the future I'm planning to install one of these:



XJ Extended Range Gas Tank

30.5 gallon TIG welded aluminum tank with a skid plate. It costs $1000, which is why it's in the distant plans and not an immediate purchase. Sure would be nice to have a 500+ mile highway range.

 

Miles per tank is a totally useless, meaningless figure. Mine is currently getting roughly 18 city, 21 hwy MPG.

 

Think about 350 miles maybe more, but hey a diesel.
Normally around 200 for £50 convert that into US, but our fuel is a rip off price.
Currently lifted 3" with 31" mt's.
I do rag it around to the surprise of cars.

 

How so?? it's called RANGE. What's the point of knowing how many miles you get per gallon if you don't know how many gallons are in the tank?

Thanks for the input guys... I just wanted to compare where I was with all the mods I've done... and still to do.


Happy Easter!

JR

 

Happy Easter everyone. Yes yes yes. Range is very important to know. Otherwise you miscalculate your trip and have to walk with a bright red can...

 

Unless it's full, preparation is key, :-)

 

My bone stock 2000 XJ 4X4 gets a combined city/highway MPG of 18. I've calculated it multiple times and it's always at or very near 18 MPG. Most of those miles are typically highway. (I recently installed a Clearwater cylinder head, but that's not really a performance mod. My MPG is the same now as it was before the new head.)

My XJ currently has cheap tires which will soon require replacement. I like to buy good tires and I'm hoping I can squeeze out a bit more MPG with the new rubber.

 

My Spectra Premium tank holds 23 gallons without any additional modifications on my part.