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-   -   4cyl. gas tank size and MPG's (http://www.wranglerforum.com/f282/4cyl-gas-tank-size-and-mpgs-87049.html)

gth-wrangler97 03-30-2011 03:36 AM

4cyl. gas tank size and MPG's
 
Ive got the all powerful and mighty (joke) 2.5 4cyl. and have been trying to figure out how big the gas tank is. Every time i fill it up i get about 13.5 gallons max and thats after basically running it bone dry.

My next question is for anyone running 33's on their rigs and how many miles they get out of a tank and what their gas mileage is.

jvc 03-30-2011 08:04 AM

highly probably that your gas tank is 15 gallon capacity.
it was about 1999 that the 19 gallon tank was offered.

KCrisp 03-30-2011 09:47 AM

The 19 gallon tank became standard mid-1999 on the 4 cylinder models. But you can convert your tank to 19 gallons.

cedarcreekjerky 03-30-2011 10:09 AM

Im gettin about 13 mpg with 33. With stock gearing you loose 5th gear and most of your power

gth-wrangler97 03-30-2011 05:52 PM

yeh i was getting about 13-14mpg on the highway. I still cant figure out why every time i fill it up it cuts off at about 13.5 gallons... where is the other gallon and a half? and i run it nearly bone dry

pokey 03-30-2011 06:07 PM

Quote:

Originally Posted by gth-wrangler97 (Post 1148251)
yeh i was getting about 13-14mpg on the highway. I still cant figure out why every time i fill it up it cuts off at about 13.5 gallons... where is the other gallon and a half? and i run it nearly bone dry

TJ's are known for hitting E with 5 or 6 gallons left. The only way to know for sure how many gallons the tank holds is carry a jerry can with 2 or 3 gallons in it and drive the jeep till you run out. Put the 2 gallons in, then see how much goes in at the pump.

dmacioce 03-30-2011 06:10 PM

I'm not an expert (so I could be wrong about this), but I think it's designed to leave some gas at the bottom of the tank to prevent damage to the fuel pump. I suspect that the 1.5 gallons are at the bottom of your tank. I remember hearing that it is important not to tap into that reserve in order to prevent damage to fuel pump. Not sure how accurate that is, as I haven't run out of gas for about 25 years.

98tj25l 03-30-2011 06:11 PM

Pokey is right. I don't know why, but our gas gauge is around 5 gallons light. I have the 19 gallon tank, and even after running on E for a bit it only took 15 gallons. Kinda nice to know you have a reserve though.

pokey 03-30-2011 06:11 PM

^ I thought that too about the fuel pump but I read here it won't harm the pump if you run out.

gth-wrangler97 03-30-2011 06:27 PM

Quote:

Originally Posted by pokey (Post 1148266)
TJ's are known for hitting E with 5 or 6 gallons left. The only way to know for sure how many gallons the tank holds is carry a jerry can with 2 or 3 gallons in it and drive the jeep till you run out. Put the 2 gallons in, then see how much goes in at the pump.

Thats not a bad idea I may do that this weekend as im going to be traveling.

I guess it is nice to have a reserve. i guess the gauge is a jeep problem in general. Ive been driving jeeps for 9 years and everyone has has something weird with the gauge. It seems like when the gas light comes on thats like others having half a tank left.

Anomaly 03-30-2011 08:27 PM

Most, if not all, fuel gauges are calibrated to read empty even though there is still gasoline in the tank. The reason is because the typical fuel pump is lubricated by the gasoline (no oil or grease, right?!) and running to full empty is bad for the fuel system (pump, filter, and possibly injectors) because there's sediment at the bottom of the tank that gets picked up. By having a safety margin, automotive engineers created a means to have the driver get the needed fuel before running dry and damaging the fuel pump.

Conversely, a lot of fuel gauges are calibrated to read Full for about 20 miles before beginning to show any gauge movement because it's considered appealing to many drivers to not see the fuel gauge begin to go down after "only a few miles". This was more for marketing-type issues.

shipjim 03-30-2011 08:41 PM

I had a Yukon XL that ran low on gas in the desert in August. We filled it and after about 3 milles it died. Turns out the fuel pump is cooled by the gas so when you get too low in hot weather it blows the fuse and damages the pump. Lucky for me, I bought a handful of 30am fuses and made it home to Houston from Amarillo.

motokeen 03-30-2011 10:50 PM

You have to remember that if you put different size tires on and didn't recalibrate your speedo your millage isn't going to be true. I just went to 31s with my 4cyl and on a 180 mile trip it said I went like 150 miles so about 30 miles off on a 180 mile trip.

Also I have the bigger tank so it may be different for yours but my warning light comes on when I still have 3 gallons left. So its possible you still have 1.5 gallons left on empty.


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