car help please

[Brak]

alright, i got a 71 cadillac eldorado. its in great shape and all, and the engine runs awesome (got it to 60 today).
but the gas mileage is freaking me out. im not expecting a lot, but its really, really, REALLY bad. last week i got the lines replaced because they were in SHREDS, and i thought that would fix the problem. but it seems to me that it didnt do anything! now i check under the car every time before i drive it, i cant smell gas or see gas on the road. its wierd, it still seems like its getting 5mpg, when it should really be getting 10-15mpg. could someone who knows stuff about cars help me with this? what are all the places gas goes before it gets to the engine? because the plugs are fine and the carb is clean as a whistle, it still seems like its getting worse mileage than it should.

[HoppysMag]

well it does seem a little low. but dont expect more than 10 mpg

new the car gets 10-13 but its old. so feel lucky if you get 10

[taylor492]

Do u live in the ghetto? Cuz people might be siphoning it outa your tank

[Brak]

Do u live in the ghetto? Cuz people might be siphoning it outa your tank

no, i dont live in the ghetto, and nobody can syphon gas outta my tank because the gas cap is hidden behind the liscence plate... old-school.

if i get 10 mpg id be happy, but im getting nowhere near that much, thats what my concern is. maybe my guage is funked up?

[HoppysMag]

no, i dont live in the ghetto, and nobody can syphon gas outta my tank because the gas cap is hidden behind the liscence plate... old-school.

thats never stoped me

[Chris42050]

A 71 caddy. It's probably a boat with a crap load of miles and a big *** V-8 right. Yeah between 5 and 10 miles a gallon is all your gonna get outta it.

[Destructo6]

For a 30-year old 500cid engine, 5mpg is not too surprising. I drove a Ford F350 4-wheel drive, with a 460cid and 4v carb, which would get a best of about 7mpg.

Check out your ignition system and get it tuned. You might find another couple mpg in there somewhere.

[CasingBill]

Dude, be sure u are checking the mileage accurately. You can't go by the guage. You actually have to fill it 2X to check it. Don't just guess by what the guage says. Don't expect more than 10 though unless you are doin some hwy drivin.

[PyRo]

Make sure the car is tuned up good plugs, wires, oil, tranny fluid (change it every 20k miles or not at all if you go to long without changing it then do it your trans could let go but hey if it goes that means it was on it's way out anyway), you can usually squeeze out a few mpg playing with the carb but you have to know what you're doing.
And not everyone is too stupid to look behind the plate for a gas cap.

Also roughly calculate your MPG like this.
Fill the gas tank
Reset the trip odometer or if you don't have one note the miles on the odometer
The next time you get gas figure out how many miles you have driven since the last time you go gas
Fill up the car and note how many gallons it took
Divide the miles driven by the number of gallons the car took
That will give you an idea within 1-2mpg of what you're getting maybie it's not as low as you think.

[rehme]

is it running rich? where do you see the gas? under the car or in the engine compartment? you might want to check to see if the lines where not hose clamped down all the way.

[AutomagBoy]

First of all im an amateur mechanic so I may be wrong on a few points.

first thing double check your math, know how big your tank is, fill it completely and see if the needle on the gauge is accurate and recalculate using Pyro's description.

Now the mechanical part.

Check the O2 sensor, if old, replace.

Check your timing with a timing light if you dont have one go to an auto shop at a high school, they will be happy to help.

if you have a 4 barrel carburetor check to make sure the the two smaller barrels are opening BEFORE the 2 bigger ones. The 2 bigger ones should open at high RPM's

find where the area where the leak is from then follow the fuel lines and fix any loose connections

If all else fails and you're POSITIVE it should be getting better milage have a mechanic rebuild your carburator do not rebuild it yourself

[PyRo]

He can rebuild it himself it's just going to take a bit of trial and error along with some fires and explosions

[vf-xx]

is it timed right? If your idle is too high that'll eat up gas too.

[PyRo]

Forgot to mention the way you drive effects gas milage more than anything it's the differance between 8mpg and 16mpg in my car.