My normal fill-ups are 6-7 gallons. The fuel pump starts to whine real loud if I let it go any more than that. Even when I have run out of gas (2 times now, darn cold weather changing my mpg estimates), and have filled up the tank, I can only get in around 8 gallons. Where are the other 2 gallons? Is there a direction to tilt the car that I can actually use them (uphill, downhill, sideways)?

Edit: my only other thought is that there's crud in the tank from the car sitting for so many years. But surely there can't be 2 gallons worth!

[This message has been edited by kwagner (edited 01-24-2006).]

You are not the only one with that problem. I have done a search but have not been able to come up with a clear cut answer. I even entertained the idea of just fabricating a gas tank but as I understand it there is a plastic baffle inside the stock tank. What purpose it serves, I have no idea. My question is, what is causing for that to happen in the first place.

Mine gets I believe just a hair under 9 gallons. I just thought that the fuel pickup was such that it couldn't get to the very bottom of the tank. There is a lot of surface area on the bottom, so a gallon or two wouldnt be very deep, maybe an inch if even.

I ran an 88 out of gas just as I was pulling into a gas station and all I could put in was 10.5 gal

the rest of the fuel is below the fuel pickup.
the bottom is ALWAYS wet.
the capacity of the fuel tank is 11 or so gallons, but, since the fuel pickup doesnt go to the bottom, it cant pump out all 11 or so gallons

yes, the 6-8 gallons fill-ups are pretty cheap, but when you get 20 or so MPG, its alot of fuel stops.

with better baffling & lower pickup, you MIGHT be able to get another gallon of usable fuel. I plan a new fuel pump soon anyways, I'll ponder what can be done for more range. maybe a trap box around the pickup like they use in racing.

------------------
1985 Fiero SE - Plain Red V6 Coupe
3.1 Crane272 MSD 4.10-4spd DarthChip Borla
D.A.M.M. - Drunks Against Mad Mothers

humm

I have a 86 gt

I average about 10.2 on a fill up and this is on a regular basis, and to think I was complaining and thinking about a 88 with a bigger tank

I guess I will just keep my mouth shut

tim

I ran my 86GT sputtering into the gas station ONCE, and it wasn't on purpose, and I put in 9.6? galons? Somewhere around there. I won't do that again. I like to fill up around 8 or so gallons, sometimes 8.5. I usually REALLY top off the tank tho, when the gas nozzle clicks off the first time, I usually put in an extra gallon. I think the vent tube really foams on these for some reason, causing the nozzle to shut off prematurely.

Just my 2 cents anyway.

Mine is an 86gt as well. I don't understand how some people can get 2 more gallons in a fill up than I can. I've even tried filling until the hose clicks off, waiting a minute, then repeat. Still 8.6ish, if that. If it wasn't my daily driver, I'd drop the tank and take a look.

The only thing I have thought of so far for a better tank design was to separate the fuel tank into smaller compartments with openings at the top for overflow into each other (so when you fill the tank, it fills all the compartments). Then link the compartments together with fuel line at the bottom. Like an ice tray for fuel. With a smaller surface area per compartment, you'd get more total usable gas. But I haven't thought it out that much, just an idea.

And to think that I thought my car was special . I haven't seen my 88gt fill up with more than 9g yet, I've never filled it after running it out of gas though, so I'm not exactly sure what the capacity is. Usually it fills with 7-8 gals when it's low.

Also if you has put a slight forward cant on you car by lowing the front springs that is going to leave more gas in front of the pickup since it is located toward the rear of the tank. The spec'd tank size is the complete tank. You will never get all of it since air in also in the top.

I located my pickup on the bottom when I replaced my pump and can get 10 out of my tank if I wanted to. (88 GT)

I never do since I don't want to replace my pump again that soon..

I put 11 into my 88 a few years ago. It's not something I try to do on a regular basis.. running out of gas is no fun.

http://www.hotrod.com/howto/70438/

For a future upgrade I have been thinking about installing a fuel tank sump and an inline fuel pump.

Tank capacities I believe changed in about 87 to a least another 1.5 to 2 gallons larger in capacity.

The '84-'86 tanks are supposed to be about 10.2 or 10.3 gallons total, the '87-'88's are 11.9. When I ran out of gas in my '88 GT last summer by accident, I got a little bit of gas from a friend and when I went to fill up less than a mile later, I filled 11.5 gallons. That's in an '88 GT that had 37,000 miles on it at the time, although it probably sat a lot. The less the miles the less crap in the tank, so the more you can fill it up? In my '86 SE with 133,000 miles it'll usually get 7 gallons, 8 if I push it down to the E, it must have a LOT of crap in there . I haven't had the chance to run it out of gas yet though .

------------------
I am the signature virus, please put me in your signature so I can spread

For the latest Fiero apparel and accessories, please visit F-I-E-R-O's online store Fiero Lives Online

I don't know if this makes a difference, but I ran my tank to virtually empty where I heard the pump, then zeroed the gas needle to just a tad below empty on the gauge, then filled up the tank with gas I keep in the trunk.

When full, I am a little over the full mark and when the needle is on empty I know I am empty.

I also use the slowest fill position to prevent air blockage etc.

tim

I put in more than 10 gallons all the time. In both an '84 and an '87. Yes I run low alot, but I, seem to be one of the few, have a good working gas gauge. Sometimes the baffle inside breaks, and can cause no accessibility to the remaining fuel. You want an intank pump, instead of inline, as the fuel cools the pump and you don't get vapor lock. If you havent looked at your pump, it could be missing/trashed the fliter boot on the bottom causeing your pump not to stay all the way down. Best thing to do is pull the tank and look.

------------------
"DRIVE IT LIKE A FIERO"
'84 Fiero, engine to be determined
'87Blue GT 3.4L Swap Completed!!!!!!!!
http://www.lasvegasfieroclub.com/

You have to put gas in slowly and dribble the last few gallons in...

First fill the tank at 1/2 the speed you usually fill it.. Wait until the pump shuts off each time you squeeze the pump trigger...... NOW.. wait about 20 seconds, then dribble the gas in with little dribbles.., Wait for 5-10 seconds each time the pump shuts off. As the tank fills, pull the filler nozzle a bit more out the filler opening... You'll see you can do this for some time and you should get at least an extra gallon in... It takes me an extra few extra minutes to fill doing it this way, but the extra gallon means I can go farther between fills

------------------

1988 Fiero Coupe 2.5L
1990 Trans Am GTA 5.7L

The evap cannister is below the gas cap so if you fill it to the brim you may flood the cannister.

I've gotten 10.1 in my 86SE. I assume I was on vapors. I usually fill it up at 1/4 tanks and it takes about 8 gallons.

My fuel pump whines and my car cuts out on hard turns at 10.5 gallons or so. One thing to consider is the amount of fuel that fills the fuel lines, filter, and fuel injector rail. That probably totals up to half a pint, maybe more, and it can't be used because once the pump sucks air it can't maintain pressure in the rest of the system and the engine quits.

JazzMan

You dont want to be filling 10 gallons for 2 reasons,

As stated, overfilling the tank will flood the vapor canister, and

The fuel pump is gas cooled, running it to empty means it isnt submerged anymore, so its running hotter than normal

Anyone who's put more than 10.3 gallons in a pre 87 tank should call the local regulatory agencies, lol.

------------------
Boost is like Venereal Disease, one night of passion can result in weeks of pain (and work.)
http:\\www.myspace.com\keeptherubbersidedown

If you run down an 84-86 tank as empty as you can get, so there is still say 1/2 gallon in there. You can still put 10 gallons in. If you fill it to the "Brim" and I mean to the point that is comming up the filler neck. The neck itself holds about 1/2 to 1 gallon of gas from the tank to the top.

As for vapor canister. I don't have one. I removed the thing ages ago. No reason to aside from cleaning up the engine bay and removing a ton of vacuume lines.

------------------
85GT 5spd ,93 Eldorado 4.9 Dual O2 Custom Chip, Archie Clutch. Custom Exhaust. MSD Everything 245/50/16's Cant wait for Dyno Time and Track Results. Not Your Average 4.9 Capt Fiero Com --- My Over View Cadero Pics Delta Cam and Allante Intake Soon.

Hmmmm..... I filled up my 84 from the time it was new until I got rid of it 4 years ago by patiently dribbling in the last couple of gallons until the gas was at the level of the filler cap and never once had any evidence of liquid gas in the vapor canister. I do the same thing with my 88 and can get between 2 and 2.5 additional gallons in after the pump first shuts off. The 88 does have an additional vapor tank in the right side fender area that the 84 did not have. No canister flooding in the 88 either

------------------
Rod Schneider, Woodstock, Ga.
"You can't have too many toys!"
1988 Fiero GT
1966 Porsche 911
Van's RV-6 airplane-under construction

i routinely put 25-30 litres of gas in my car at fill ups, usually the gauge never reads below 1/4 tank, and i've never run it dry so i'm not sure about that. i always just assumed i still had 5-10litres of gas still in the tank

quote Originally posted by 86GT3.4DOHC: The fuel pump is gas cooled, running it to empty means it isnt submerged anymore, so its running hotter than normal

Ummm... most fuel pumps that I have seen are cooled by the fuel passing through them... not the fuel surrounding them. The gas goes right through the motor, which takes heat away with it. Running them dry is what will kill them fast as they are lubricated and cooled by the gas they pump.

I routinely put 9.5+ gallons in my 87. I haven't run it dry yet, but my fuel gauge is somehow more accurate than that of any other car I've ever driven. When it is down to pointing at the last little bar, I can put almost exactly 10 gallons in without resorting to any tricks. I haven't run dry yet.

------------------
"I love Fiero."
"Do you really love the Fiero, or are you just saying it because you saw it?"
"I love Fiero! I love Fiero."

'87 Pontiac Fiero GT

Well I filled up 'normally' this morning to the usual 6.5 gallons, then I tried to dribble some in after waiting, hit cut off, repeat a few times. I could only get in about .2 gal every time before it would cut off, and I squeezed the trigger as light as I could. I got to about 7.2 gallons before I decided I had to get going. The tank wasn't at empty though, so I think that was pretty good. I could have gotten more in, but not sure how much more, or how to tell when to stop before it overflowed.

Also a factor is each pump tends to have a different sensitivity, even at the same gas station. Just something to throw in to the mix

after recently dropping my fuel tank to do a pump, another thing i found was that the fill neck isnt really in the top of the tank either, its more on the side...ummm ill try to do a little ghetto picture here

not like this
........../ Fill neck goes in here
____/---\____

more like this....
______
...........\ < Fill neck goes in here

sorry thats the best i could do.....but maybe thats another reason....im sure once you start filling up that neck, there prob some space above that fuel neck in the tank that doesnt get fillled either....and on another note, my fiero has 130,000 on it, NOTHING on the bottom of the tank when i droped it, other than gas...

[This message has been edited by KeithGT (edited 01-26-2006).]

Good info. Thanks!

The fuel pump in my Formula ('88 of course) begins sucking air at about 6.5 gallons, but the bottom/rear of the tank was bashed in slightly at some point by a previous owner. Also, the pump pickup needs to be located as low as possible to use all of the fuel in the tank, and I suspect that some replacement pumps are mounted higher than they should be.

I'm hoping that the replacement tank and pump assembly I have will help with my problem ... just as soon as I get around to installing them.

[This message has been edited by Marvin McInnis (edited 01-26-2006).]

quote KeithGT:...ummm ill try to do a little ghetto picture here not like this ........../ Fill neck goes in here ____/---\____ more like this.... ______ ...........\ < Fill neck goes in here

You mean more like this:

BD, the filler neck is submerged when at about 3/4 a tank. Also the breather tube (the smaller dia. tube to the right of the filler tube in the above pic) is submered at about the same time. What really counts then is the vent line at the top of the tank on the removable plate that holds the fuel pump lines.

The whole PROBLEM of filling is usually caused by the vapor RESTRICTOR in the vent line that forces the air to vent slower than the fuel is pumped in. The vent line goes to the vapor canister.
See Page 6E2-C3-3 of a 1986 Fiero Service manual.
Fig C3-2 Evap. Emissons Control System Schematic - 2.5L

BTW By unclamping the Vapor canister in it's bracket, the canister can be raised slighty if one is concerned about liquid contanimation.

Can someone scan the pic from the service manual & post it for all the non-service manual members.

[This message has been edited by 30+mpg (edited 01-26-2006).]

I filled the tank on my 86 today. When I pulled into the gas station I had 1/4 tank and I was able to add 7.6 gallons to it.

------------------
Low 14 sec 99 Pontiac GTP, 3.2L V6 4 sp 86 Fiero GT

Is there any other way for the tank to breathe other than thru the vent RESTRICTOR once the gas cap is screwed in place?

The originator of the thread commented that his fuel pump started whining. Sereral other threads I've seen in the past talked about a plastic component of the pump that will crack and allow fuel to run back into the tank. When the tank is less filled the pump has to pull the fuel further and loses pressure apparently. If that is the case (no first hand experience here) then when the pump can't create enough pressure, the engine dies and you believe you are out of gas. Could deteriotation of the fuel pump be part of this variation?

I admit, I did not realize how restrictive the evaporation line is. I'll have to see if my gauge is different depending on how fast I fill it to the automatic cut-off at the pump.

Brian

After reading this thread last night I remembered that I need to get fuel. I hopped in the car('87 GT) and cruised down to the gas station. The car was very low on fuel. I topped it off at 11.55 gallons. I took a couple of pictures with my phone (crappy pictures because of all the fuzz on the lense). The first pic is of the car and the second is of the pump.

3atsH0ndas

www.FieroSpeed.com coming soon!!

quote Originally posted by 30+mpg: You mean more like this: BD, the filler neck is submerged when at about 3/4 a tank. Also the breather tube (the smaller dia. tube to the right of the filler tube in the above pic) is submered at about the same time. What really counts then is the vent line at the top of the tank on the removable plate that holds the fuel pump lines. The whole PROBLEM of filling is usually caused by the vapor RESTRICTOR in the vent line that forces the air to vent slower than the fuel is pumped in. The vent line goes to the vapor canister. See Page 6E2-C3-3 of a 1986 Fiero Service manual. Fig C3-2 Evap. Emissons Control System Schematic - 2.5L BTW By unclamping the Vapor canister in it's bracket, the canister can be raised slighty if one is concerned about liquid contanimation. Can someone scan the pic from the service manual & post it for all the non-service manual members.

Exactly...only i didnt have a spare fuel tank to cut apart...lol

The tank CAN "inhale" thru the one way valve in the gas cap. It must exhale thru the vent tube or the fuel line.

It is possible for the vent RESTRICTOR to become partially or completely blocked.

quote Originally posted by s550w: The originator of the thread commented that his fuel pump started whining. Sereral other threads I've seen in the past talked about a plastic component of the pump that will crack and allow fuel to run back into the tank. When the tank is less filled the pump has to pull the fuel further and loses pressure apparently. If that is the case (no first hand experience here) then when the pump can't create enough pressure, the engine dies and you believe you are out of gas. Could deteriotation of the fuel pump be part of this variation?

You know, that's a really good question, and one that I don't immediately know the answer to. It would be nice if the whole problem was my fuel pump, kill two birds with one stone and all that. I'm going to have to replace it soon anyway. Has anyone with a 'whiny' fuel pump replaced theirs, and noticed you could get more fuel out before running out of gas?

Bump...I'm curious if my thougfht actually had any merit.

Epoxy an L shaped tube into the vent tube that is to the right of the filler tube.

Position the top of the L close to the top of the tank.

This raises the vent point, decreases the size of the trapped air chamber & speeds filling.

More air would exit via the air vent on the filler neck instead of trying to squeeze thru the vent restrictor.

[This message has been edited by 30+mpg (edited 02-01-2006).]