Hello,
I was just wondering how big is our gas tank?? How many gallons will our stock tank hold?? and also what mileage should a stock 92 rs get on highway and city.

Thanks

 

The Tank is 15.5 gallons. City is supposed to be something like 17 MPG, while HWY is supposed to be something like 21 MPG. I've never got either though.

 

I've never gotten more then 14-14.5 gallons in my tank. I usually get about 17 miles in the city though.

 

The tank can hold 15.5 and about another half gallon in the neck if you really fill it. Your owners manual will have all the fluid capacities for your car. Mileage depends on the state of tune of your car. With only a cat back and open element I could get 31mpg all day long on the highway.

 

31 mpg?!??! man, you guys are nuts. I wish i could get that, maybe after my full exhaust install....not likely...

I usually get 17 mpg, and 14 gallons in a tank, although im sure thats b/c i never run it totally dry.

My best ever was 20mpg, and that was all highway, never broke 2000 rpm's the whole tank, never used the AC, and always had the windows up on the highway (dont laugh, it does make a difference). Gotten as low as 11-12 before, that was a fun one.

-chuck

 

Well a lot of the difference is in the FP settings. GM did not have a standard stock setting for these cars and some got higher than others. That combined with a good tune (meaning tune up) can produce amazing mileage results.

 

Everything is still stock in my rs. Is there anything I can do to improve my gas mileage in my little 305 TBI??

 

A really good tune up will go a long way.

 

Will replacing my exhaust with flowmaster and no cat help any??

 

Also what does a "really dooe tune up" consist of. What parts should I replace?

 

https://www.thirdgen.org/techbb2/sho...hreadid=162251
Of course use common sense, if you changed your tranny fluid a few thousand miles ago there is no reason to do it again.

I get from 9mpg up to 22. 9 would be going very slow through backroads, stopping often, i'm talking a 5mph average. 22 on the highway.

 

Check out the new to TBI thread at the top of the page. It will cover what a tuneup for these cars should consist of.

 

I would also like to know, cause my 89 is tuned up and my tripometer doesn't work and the gas gauge fluctuates. I filled it up to the brim where gas was leaking out of the filler neck and the gauge never went all the way full. ??? It only took 13 gallons and the needle read all the way empty when I went to the gas station, as a matter of fact, I took a 1 gallon gas can with me cause I didn't think I was going to make it and it turns out I still had 2.5 gallons left? Right now I am pushing 200 miles on this full tank and I need to know how far I can push it before it goes dry, cause I hate putting gas when I THINK I am empty and then it turns out it only takes 11 gallons.

 

To put it simply our gas gauges suck. GM probably made them read a little low intentionally so people didn't run out of gas. Ive also heard its bad for the fuel pump to run that low.
How long have you had the car? After you fill it up a few times you should be able to guess fairly closely how much gas you have left.
The fuel pump is cooled by the gas as well, so its probably better for the pump to keep a decent amount of fuel in the tank.

 

Now that 31mpg that Shifty is talking about is probably gonna be for the TBI and not the TPI. I think the LO3's got better gas mileage. Before the mods I typically got 25mpg in my RS. It's down to about 22mpg's now. But I'm not complaining.

As far as our gas gauges go, if you look at the shape of our tank it is slanted. And I think the sensor in the tank is calibrated to read on a straight up and down level. But since it is slanted there is more area at the top of the gas tank. That is why the first half of the gas gauge moves slower than the second half.

Think of it as a cup that has a smaller bottom than a top. As the fluid tapers down to the smaller area, it looks like it is being used faster even though the flow rate may be the same.

Does that make sense? I think it does.

 

You can also have some fun with our stupid gas gauges. If you take a turn pretty fast the gas will go to one side of the tank and the gas gauge will read really low and then bounce back up again after you stop turning. If you like taking fast turns this makes it even more fun.

 

Ben, you don't live a very exciting life, do you?

 

You must have a tank that is not baffeled. Mine stays pretty put on hills and high speed cornering.

 

Where are the fuel filters? ive heard they should be cleaned/changed. And is that FP regulater free mod worth doing? how do you know you have it adjusted right, or how do you adjust it?

-chuck

 

There is only one fuel filter and it is just aft of the driver side seat on the rear of the car. It looks like a little metal cylinder. The fuel pressure regulator mod is worth it if you can take advantage of it. You will know if it adjusting if the screw goes in as you turn it. This will press a dyaphram up on the spring and partly compress it.

 

but how do i tell if it is adjusted right? those fuel filters prolly need changing dont they? 100k+ on them. I would want less preassure then there is right now b/c it comes rich from the factory right?

-chuck

 

The only way to determine if you are really blessed with the GM factory rich setting is to datalog and check for yourself. You cannot gaurantee that you are rich. The regulator mod is if you have some mods that require a bit more fuel but don't want to make the changes in the chip. It is a trial and error with data logging to set FP without chip burning.