I have a 1999 Jeep Wrangler that I just bought.

WHAT ENGINE?

WHAT KINDA NON-STOCK MODS (INCLUDING TIRES)

YOU HAVE A 19 GALLON TANK

DO YOU SMELL GAS?

WHAT DID YOU DO AS A TUNE-UP?

DOES 2WD AND 4WD OPERATE PROPERLY (FRONT AXLE IS FREE WHEELING. BY ACTUALLY CHECKING---NOT RELYING ON THE CONTROLS)

IS YOUR CHECK ENGINE LIGHT ON. DOES IT "DISPLAY" THAT IT WORKS, AT START-UP?

THE MEDIC

OK

I APPRECIATE THE WAY YOU ANSWERED MY QUESTIONS---USUALLY I HAVE TO DRAG THEM OUT OF PEOPLE AFTER MANY RESPONSES I MIGHT GET THE INFO I WANT!

DO YOU KNOW HOW TO FIND YOUR ACTUAL MPGs STARTING OUT WITH A SLAP FULL TANK OF FUEL---WRITING DOWN THE ODOMETER READING

-DRIVE IT DOWN TO, LET'S SAY, A 1/2 OR A 1/4 TANK?

REFILL TO "SLAP FULL" AGAIN

WRITE DOWN THE ODOMETER READING----AND THE EXACT GALLONS IT TOOK TO REFILL IT

THEN DO THE MATH

...........SORRY SOME PEOPLE OF THE NEW GENERATION THINK IT ONLY CAN BE FOUND BY LOOKING AT THE DIGITAL STUFF WHERE IT TELLS YOU MPG AND HOW FAR BEFORE YOU RUN OUT ON THEIR "CYBER CAR"!

I'M REALLY UP ON CJs--AS I HAVE OWNED 5 PREVIOUS CJ 5s--AND PRESENTLY OWN A '77 CJ 5 AND A '46 WILLYSNEVER ANYTHING ELSE SINCE 1981, WHEN I STARTED DRIVING ON ASPHALT

MAYBE NOT RELEVANT TO YOUR SITUATION----NONE OF THE CJs EVER RUN EXACT. I UNDERSTAND HOW TO BEND THE FLOAT ARMS AND DO SOME PRECISE MEASURING--CHECKING OHMS.....ALL BEFORE INSTALLING A CJ FUEL TANK SENDING UNIT......IT'S STILL NOT DEAD ON

CJs COME WITH A 15 GALLON STOCK TANK---I'VE UPGRADED TO A 21 GALLON POLYETHYLENE---THE CORRECT SENDER OUT OF THE BOX WAS OFF---TWEAKING MADE IT BETTER---BUT STILL I CAN DRIVE RIGHT AT 100 MILES WITH A "SLAP FULL" TANK (ACCORDING TO MY GAUGE) BEFORE THE NEEDLE MOVES DOWN AT ALL. .....STRAIGHT OUT OF THE BOX, IT WOULD SHOW "EMPTY" WHEN I HAD 4 GALLONS LEFT?????

IT ALL IS GEOMETRY, AS WHERE THEY "CROOK" THE FLOAT ARM---THE LENGTHS BETWEEN THE "CROOKS"---AND THE RELATION OF THE RHEOSTAT TO THE ARM POSITIONSYOU CAN ONLY TWEAK SO MUCH

NOW "WILLY", MY '46 WILLYS, ON THE OTHER HAND, HAS A 10 GALLON TANK. I BOUGHT AN AFTERMARKET SENDER FOR HIM

IT IS EXTREMELY ACCURATE--THE SENDER WAS DESIGNED FOR TANKS 6-24 INCHES DEEP. WILLY'S TANK IS ABOUT 6 INCHES DEEP AND UNDER MY SEAT. THE INSTRUCTIONS FOR THE SENDER SHOWED HOW FAR TO THE PIVOT (BASICALLY 3 INCHES---1/2 THE DEPTH OF THE TANK). THE OTHER CRITICAL PART WAS HOW FAR OUT DID THE FLOAT GO FROM THE PIVOT----SO WITH MINE, THE FLOAT ARM GETS CUT OFF A SPECIFIC LENGTH, AS PER THE INSTRUCTIONS

SO THE FLOAT ALL THE WAY DOWN IS "EMPTY"TOUCHING THE INSIDE TOP OF THE TANK IS "FULL".............REALLY ACCURATE, AS THEY HAVE ALL THE MEASUREMENTS PERFECT FOR WHATEVER DEPTH YOU NEED! THE COMPONENTS HAVE "SET SCREWS" AND NO BENDING IS INVOLVED.

THE ONLY DRAWBACK IS.......THE FUEL GAUGE IS SO SENSITIVE....BOUNCING DOWN THE ROAD.....IT "FOLLOWS" THE SLOSHING FUEL.......THE GAUGE HAS AN IMMEDIATE REACTION AND THE NEEDLE IS IN CONSTANT MOTION---EVEN ON A SMOOTH ROAD IT'S BARELY MOVING UP AND DOWN

THIS WAS THE SOLE REASON I DID NOT PUT ONE LIKE IT IN MY CJ 5s 21 GALLON TANKI'M USED TO IT NOW, SO IT'S LIKE A "FREE 100 MILES TO ME, EVEN THOUGH IT AIN'T!

BEING THAT I HAVE NOT EXPERIENCED YOUR FLOAT SITUATION 1ST HAND----I HAVE DONE A LITTLE RESEARCH ON IT FOR YOU.......MAYBE NOT ENOUGH YET!

I SUSPECT YOUR FUEL MILEAGE IS A CONSTANT VALUE---WITHOUT LOOKING AT THE GAUGE

I ALSO SUSPECT SOME OF THE FOLLOWING

THE SENDER COULD BE BAD

SOMEONE ELSE INSTALLED IT WRONG........I'LL EXPLAIN IN A BIT

SOMEONE TRIED TO TWEAK IT, WHO WAS SORTA LOST

IT GOT BENT DURING INSTALLATION

I LOOKED UP THE FUEL PUMP AND SENDER----THIS IS IT BELOW, IN THIS LINK

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_fuel-pump-module-assembly-airtex_18770712-p?searchTerm=fuel+pump+module+assembly

THE "CROOK" IN IT----BASICALLY "WHERE THE CROOK IS" OR THE ANGLE IT IS BENT AT---WILL ULTIMATELY AFFECT.........WHERE IT "THINKS" FULL AND EMPTY ARE AT........IT MAY ALSO EXPONENTIALLY FALL FASTER IN THE BEGINNING---AND SLOWER TOWARDS THE END

EVEN A SATURATED FLOAT BALL--1/2 CRUMBLED AWAY BALL---TWISTED AND STANDING ON END---MIGHT FACTOR IN

DOES THAT MAKE ANY SENSE?

ACTUAL FUEL USAGE WOULD BE CONSTANT AND THE SAME, THE WHOLE TIME, THE GAUGE JUST FOOLS YOUTHAT'S WHY I SUGGEST YOU DO SOME NORMAL DRIVING AND CHECK YOUR MPGs AT A FEW DIFFERENT FUEL LEVELS

WANNA SEE THE FACTORY MANUAL? I SORTA SKIMMED OVER THE FUEL PUMP/ SENDER/ AND TANK PARTI SEE NO ADJUSTMENTS (TWEAKING WOULD BE AT YOUR OWN ACCORD)

I WILL EXPLAIN HOW I DO IT WITH THE UNIT OUTSIDE THE TANK...IF YOU WANT ME TO

THEN WE GOT THE..................MAYBE THE GOODIES INSIDE THE GAUGE ARE MESSED UP?????

THIS MAY BE EZier TO CHECK

BELOW---WHEN I LOOK UP MY CJ 5THE MANUAL GIVES THE TESTING PROCEDURES AND THE OHM READINGS THAT SHOULD BE PRESENT---THUS LETTING YOU KNOW WHICH END OF THE JEEP IS FAULTY (I DID NOT LOOK YOURS UP--SO I DON'T KNOW IF THEY SHOW IT)

HERE'S THE FACTORY MANUAL---YOU HAVE A '99 "TJ"----INSTALL YOUR INFO---THEN "FUEL SYSTEM"

MAYBE NOT THE LEAST EXPENSIVE---I MAY CAN HELP IN THE "GET STUFF CHEAPER DEPARTMENT" ALSO...IF YOU LIKE

BUT I DID FIND THAT THE SENDER---IS AVAILABLE BY ITSELF, NOT AS PART OF THE PUMP ASSEMBLY......AND MAYBE CHEAPER SOMEWHERE ELSEI WILL GIVE MORRIS CREDIT WHEN I CAN, THE "FREE MANUALS" ARE GREAT, SO FAR THEY ARE THE ONLY ONE OFFERING THEM........I HAVE THE REAL--PAPER VERSION FOR THE '79 CJ 5

http://www.jeep4x4center.com/level-unit-package-4897757ac.html

SORRY....I GET ALL CARRIED AWAY AND STUFF, WHEN IT COMES TO "REAL JEEPS"

YOUR TURN

THE MEDIC

AMONG MY PICS---MY DAUGHTER LIKES SHOWING OUT, CRANKING WILLY WITH THE HAND CRANK INSTEAD OF THE STARTER.......SHE WAS 10 YEARS OLD THEN, AND CAPABLE OF DRIVING HIM IN ANY MODE

WILLY LOOKS LIKE A TOY IN THE GRASS IN MY "DEER STAND GLAMOUR SHOT"

If you are losing that much fuel, you would smell it. If you have a 19 gallon tank and according to your info, you drove 290 miles until it was at 1/8th tank, that is an average of 15.26 miles per gallon which is average for your vehicle. As far as the gauge and how quickly it drops, like CJ MEDVAC said, chances are you have a bad sender unit or someone didn't install it correctly. Regardless of how fast it falls, you got the average MPG for this vehicle. That and the fact that you don't smell gas, tells me there is no leak.