fuel tank question

[EHB]

i just got my 2000 GTP on the road a few weeks ago and did my first fuel fill up . i have an 18 gallon tank and i'm sure it is because i just put a new tank and filler neck on it. here's what's confusing me . the DIC says i'm getting 11.7 MPG (which sucks) and has been probably 95% city miles 25-45 mph , and the DIC says i've used 12.6 gallons (93 octane) , and i set the trip meter and i have driven 147.8 miles . so the DIC is pretty accurate.
the problem is the low fuel light is on and the gas gauge is in the orange just above Empty. according to my math 18 - 12.6 = 5.4
so why am i on empty and the low fuel light on when i still have 5.4 gallons of gas in the car ? i know the fuel pump has been replaced because the previous owner left the receipt in the car . is it possible the pump is different and doesn't go as low in the tank as the original ? i wanted to run the tank as low as possible to see how far / long a full tank will go and filled up a can for the trunk in case i run out, but i'm afraid of running out at a bad time on a busy road with no where to pull off.
when i filled it i filled it till gas was running back out.
anyone else have this with their GP is it normal for these cars ?

[Scottydoggs]

my car has 4 gallons left when the light comes on. some law states your supposed to have a 100 miles of gas left when the light comes on. so at say @ 25 mpg hi way 4 gallons is a 100 miles.

every gauge is a bit different tho with just how low the gas is when the light comes on.

[EHB]

at 11.7 mpg with 5 gallons left i don't think i'll be going 100 miles ..lol
i was just curious as to how far down the tank will it still pick up fuel. maybe the float got a little bent or something and is showing less fuel than there actually is . either that or it's not really an 18 gallon tank. i know in my old Z24 the light usually came on with less than 2 gallons left so i had about 20 miles before she started sputtering.
i've never had a car that wouldn't get at least 200 miles out of a full tank ...especially one that holds 18 gallons .

[Scottydoggs]

well clearly if your seeing 12 mpg gallon, and your driving local you'll only have 48 miles left in the tank. its just how this dumb low gas light law was written. if you were to follow the cars avg mpg from the factory, you'd have a 100 miles of travel left.

you also have a 17 gallon tank. not 18.

the pump sits at the bottom of the tank, so it will run till its out of gas. if there was a 1/2 gallon left in there after the car stalled out i'd be surprised.

im in the same boat, i do 99% local driving, all stop and go and get 12 to 14 driving around with a bit of gas pedal play here and there. if i drive it like grandma ill see 16. once im on the highway im in the high 20's.

[EHB]

it's advertised as an 18 gallon tank. 68 liters
http://www.rockauto.com/catalog/more...nid=447&jpid=0
plus i jammed it full to the top of the filler neck.

i've been pretty good about keeping my foot out of the pedal but it hasn't seemed to help . i got new O2 sensors to install yet hoping that might help , but it's probably just wishful thinking. i'm also going to try a new MAF sensor. can't hurt right ? 118 miles i'll just right it off as preventative maintenance.
i'm just waiting for the weather to break then i plan on tackling the exhaust with a zzp 3 inch DP and a powerlog. hopefully that might gain me an extra mile or two.
thanks for the input SD , it seems like your the only one that responds to us mechanically challenged newbs.

[Scottydoggs]

in my sig is the list of mods i have. my mpg really didnt change. still suck if im all local driving.

[EHB]

i panicked and filled it up today . the needle was a hair above the E line and i squeezed 13.99 gallons into it. might have been able to put a few ounces in it but i was at an even 37 dollars. i can't believe that there's 3 or 4 more gallons left when it says it's empty .

[Scottydoggs]

thats a nice reserve.

[EHB]

it's the complete opposite of the Z24 i'd driven for the last 20 years . that car had a 15.2 gallon tank. 6 gallons from the E mark and it would read a half tank although 7.6 gallons was actually half a tank . so from half to full was really 9 gallons. in this car it appears the bulk of the gas is below the half mark.

[adamroblyer]

I was getting 11.5 mpg on the dic in my 01 gtp until I changed or my ignition switch because my heat quit working. The dic loses voltage and resets. At this point I'm getting 20+ mpg's.

[EHB]

so you were always getting 20+ , your DIC was just giving you bad info. my DIC may not be exact but it's gotta be close. my mileage should get slightly better as it warms up because i won't be warming up the car. i also spend to much time idling in fast food drive thru's.

[mikejohnlewis]

My DIC starts saying low fuel when the range is 50 miles left, not sure how many gallons, it says I currently get 20.21MPG

[adamroblyer]

Yeah I was always getting 20+. I had just bought the car and my girlfriend drove and told me it sucked because there was no heat and I got a little offended. I talked to a few buddies and they pointed right to the ignition switch so I replaced and it took care of my heat issue and the dic issue.