how many gallons is my gas tank??

i am trying to figure out how many gallons  i hold so i can estimate my mileage. in the city around san francisco i am getting 100 miles to a half tank but that doesnt really tell me much.

I think it's 25 gallons. (24.6 to be exact)

so if i am getting 200 miles city to the tank thats only 8 mpg?!?!? arent i supposed be up at 10? is this an indicator of another problem ? i use the highest octane available which is usually 91 in cali

Well it is a 6000lb 4x4 SUV for starters. But you could probably do some small maintenance and increase that to 10. I run 93 octane and I just poured in some seafoam, which by my numbers, has me varying between 9 and 11 mpg city. I never really get out on the highway much.

Also you might want to take a look at your air filter, make sure it's clean. Next I would check everything related to air-intake. Check the MAF and spray some T-Body cleaner on your T-body. Open up the intake valve and spray in there really well. First time I did this it REALLY helped my rover purr. Just a side note, I placed an old towel under the t-body when I sprayed. A lot of gross fluid will come pouring out when you do this. And I'm pretty sure that stuff isn't great pouring down your engine around your plugs and wires. A happy rover usually means a happier wallet when it comes to mpg. They say the fuel filters are supposed to last a long time, but a clean filter means better flow, which in result leads to a more efficient engine. So you might want to look into that.

These are all easy, cheap fixes that could boost a few mpg perhaps. More importantly it will make you feel more at ease about your disco. Keeping the MAF and Tbody clean will prevent other problems, ie codes. And the more time you spend under the hood, familiarizing yourself with it, the more comfortable you will become with troubleshooting.

Hope this helps get you started towards a more efficient, cleaner burning rover.

-W

Thanks so much for tha input...
But I have to admit, I don't own and never have had an owners manual... soooooo i don't know where the air or oil filters are, I also don,t know how to get into air intake or what the MAF. And truthfully this is the first vehicle I have ever owned which has required so much of my attention to its engine. Don't get me wrong I love it. I am learning so much and have made friends with a few mechanics along the way. I have decent understanding of engines. And I like to think I am some what intelligent... Where can i get a diagram of my engine? I am planning a cross country drive and wanna get this stuff done.

Hey aublec22-
I'm in SF too and get about 9 mpg.  All city driving and one round trip to San Ramon, my Disco has gotten 225 miles on a full tank.

when i drove out from ny i was gettin 325... maybe 300

quote:

ORIGINAL: aublec22

when i drove out from ny i was gettin 325... maybe 300

Fill up your tank and reset your trip counter. Run it down and when you fill it up again, record the gallons. Look at the mileage on the trip counter and divide by the number of gallons it took to fill up. That is the closest you are going to get to exact mileage. Do it 3 or 4 times and average it.
 
 
Also, get a Rave CD from ebay. It has the workshop manual and all you ahould need for under $10. Your air filter is in the box at the front of your engine. (driver's side) The oil filter is on the passenger side front bottom. Might have to remove some plastic to get to the oil..

If you stand infront of the trk the airbox is on the right behind the headlight. There is a tube connected to it, follow that to a thing with wires connecting to it, that is your MAF (mass airflow sensor)
Continue to follow the tube to the engine, that is your throttle body. Run the drivers side of the trk up on a 2x4 or a curb and then take a screwdriver and loosen the clamp from the t-body.
Take your can of carb cleaner and spray the t-body inside and out. Use the whole can if you need to. DO NOT SPRAY ANYTHING INTO THE MAF!! Reattach the tube and start the trk. It will start hard because it will be flooded.
You do not have a servicable fuel filter, it is inside the gas tank and is changed when you replace the fuel pump. D1's have a inline filter.
Check your tire pressure, drive with a light foot and use full synthetics everywhere those are the best things you can do to help mpg.
I know that 91 octane is all that you can get in CA, and dont waste your money on octane boosters.
Iridium plugs and a good set of plug wires will help mpg also. These guys swear by Magnacor wires, I used Duralast wires with Iridium plugs this time but will use Magnacor with Iridium plugs next time.

quote:

ORIGINAL: aublec22

Thanks so much for tha input...
But I have to admit, I don't own and never have had an owners manual... soooooo i don't know where the air or oil filters are, I also don,t know how to get into air intake or what the MAF. And truthfully this is the first vehicle I have ever owned which has required so much of my attention to its engine. Don't get me wrong I love it. I am learning so much and have made friends with a few mechanics along the way. I have decent understanding of engines. And I like to think I am some what intelligent... Where can i get a diagram of my engine? I am planning a cross country drive and wanna get this stuff done.

If you were my son, I wouldn't let you drive the truck till you took the responsibility to buy a manual and infact spend many hours finding everything on the vehicle. How you can say you have spent many hours on this engine and you don't know where the air and oil filter are, is really hard to believe.
Do your self a favor and get a manual, read it cover to cover a couple of times before ever consider driving it out of town.
By the way, you need to go have a shop inspect and rebuild your front drive shaft because of a lack of grease fittings in the double cardon. Do this before you do anything else other wise you can loose your tranny and possiliy the t/case when it fails, and they do fail.

jeeeeeeez mike
 I never said i spent spent many hours on this engine. i have read a manual that i borrowed but come on i asked on tthis forum in august and in september where to get a manual. And just got an answer last night. Does the disco come with a lack of grease fittings?? how do i know that its time to have the front drive shaft inspected??

Dealers have manuals, so does Atlantic British.
Sorry about jumping your case, I have been hit with 3 other people calling this morning, one couldn't even figure where to put oil in the engine.
Seriously though, you need to spend a lot of time getting familiar with your truck, otherwise you will be paying dearly for service and repairs.
Take a flash light, crawl under the front of your truck and look where the front drive shaft hooks to the t/case, you'll see 2 u-joints inside that assembly, see if they have grease fittings, if not you need to replace them ASAP, the usual repair cost when the drive shaft fails is around $7000.
Find a small shop, not the dealer and have them replace the u-joints with new ones that have grease fittings.

I normally get around 325 to the tank when I am driving my rover.  That is all highway pretty much because I dont drive in the city out here in Salt Lake.  On sunday I managed to sneek out with 375 before the warning light came on.  So it all depends really on where you get gas and how you drive.

No more warning lights or you will burn out that near$500 fuel pump.

I had a question regarding this topic..... In the manual it says that the gas tank is 25 gallons however if I run the truck all the way down till the light goes on and then fill it up it will only take about 20 gallons.  I understand that there still is gas in the truck when the light goes on but is there really 5 gallons left?  Just wondering.  Thanks

When the low fuel light come on it means that you are now on reserve fuel. And depending on how the low fuel sensor is adjusted it can come on when 5 gal left or 1 gal left.
I had a Infiniti I30 and when the low fuel light came on I had only about 1 gal of fuel left. Found that out the hard way.
I generally dont run below a 1/4 tank just because I dont want to be looking for gas when I am running on fumes.

Ok i crawled... and i saw  the T-case is caked with oil! the joint closer to the t-case of the u joints had grease on the bolts the one in the very front end of the front drive shaft looks bone dry. Should I go to the mechanics like now?

Yes.

Might want to get a can of degreaser and spray it down at the car wash before going. If it is clean, they might be more inclined to help you out...
 
Look for a driveline or tranny shop, not all car places will do u-joints, especially the double cardan..
 
Oh, by the way, For all other on here, if you are interested, I looked up the proper spelling of cardan. I have seen it spelled several ways on here. The theory of the universal joint was first proposed to be used for transmitting motive power by an Italian mathmetician named Gerolamo Cardano in 1545. Hence, the name cardan joint.
 
There's your piece of history for the day...

damn  damn this looks bad

Why? it isn't that big of a deal. Just that some shops don't do it, and a driveline shop will do a better job. I both of mine done for $86 a piece with balancing. I don't have the double cardan, but it should be under $150 to have the front shaft pulled and done...

they checked the t case and it was leaking out of a gasket omn the front side. but very minor, they checked the fluid level and topped it off and she looks good. total cost::: $0

The capacity of the tank is not relevant in figuring your milage.

Here's how to do it without knowing capacity:

1. Fill your tank and reset your trip-odometer to ZERO Miles. You might want to really push the gas in so you're nearly overflowing to make sure the tank is completely filled... all the way full.
2. Drive either city/highway or both until you're ready to refill.
3. Refill your tank but take note of how many gallons and 10ths of gallons it takes to bring it back up to completely full. Again, push in the extra gas until it's nearly overflowing just like you did the last time - so you'll get a real number.
4. Note the number on your Odometer (which is how many miles you've driven since the last reset/fill-up)

5. Now divide the number of miles you drove (say 240) by the number of gallons of gas it took to bring it back to full. Let's say 14.83 gallons. In that case your milage would be 16.183 mpg. If you're driving my car however, it's more likely you've driven 140 miles and bought 11 gallons of gas to do it. (My LR3 is a touch thirsty!)

Hope this helps. BTW: the usual capacity for the tanks in the new ones is about 23 gallons total. The manual may say 22 or 21 but the parts guy at the dealer told me it was 23 on the box the tanks are shipped in when they need replacements.

I think my D1 is 24.6 gallons. I'm usually putting in about 20-21 gallons each time I fill up. I'm getting about 12 MPG around town (240 miles between fill ups). Which is up from about 10.5 MPG when I first got the truck. I've been running Lucas octane booster and and upper cylinder conditioner and changed the plugs. Will do the wires, plugs, cap & rotor again soon.