Less performance with a 1/4 of gas
Thread Starter
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Joined: Oct 2007
Posts: 57
The reason you see the needle plummet past half and even more after quarter tank is the tank is an irregular shape. The top half is even on both sides, but the bottom is shaped like a V. The fuel level arm uses a variable resistor, so it does not know the difference in fuel tank shape. You are not losing any performance or mpg, it is just the shape of the tank. Reset your trip counter with a full tank, and see how many miles you get before the 1/2 mark and you will see what I mean.
Yea, but Im not talking about MPG performance. I talking about HP/Torque. I am losing enough that I can tell under a 1/4 tank....
hypocrite?
Last edited by dbrown; Oct 30, 2007 at 08:45 PM.
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Joined: Oct 2003
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From: DOVER DE
The only thing that can make it run worse would be lower fuel pressure. If the pressure is falling off then there is something wrong with the pump or the bucket, either of which is not normal. Check the fuel pressure when the tank is low on fuel. If it's not correct or is fluxuating then you obviously have a problem.
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Joined: Apr 2003
Posts: 4,507
From: FTW, TX
And it kills me that people insist on talking when they don't know what they are talking about.
Our fuel pumps are in a bucket and run submerged in fuel ALL THE TIME. Even if there is only a half gallon in the tak the bucket is full. It makes NO difference how much fuel is in the tank. Even in applications that don't have a bucket the pump is still cooled by fuel because it runs through the motor.
The performance of the engine is the same no matter how much fuel is in the tank. It's in your head.
Re'
Our fuel pumps are in a bucket and run submerged in fuel ALL THE TIME. Even if there is only a half gallon in the tak the bucket is full. It makes NO difference how much fuel is in the tank. Even in applications that don't have a bucket the pump is still cooled by fuel because it runs through the motor.
The performance of the engine is the same no matter how much fuel is in the tank. It's in your head.
Re'
There has to be some circulation of the fuel otherwise the fuel will heat up around the pump and evaporate.... The thing about gasoline it that it is very volitile.
You'll probably find that your bucket is more of a baffle.
Last edited by Greed4Speed; Oct 30, 2007 at 09:53 PM.
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Joined: May 2006
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From: Lancaster, Pa
I always run premium gas in mine and I too notice that if I let the gas get around a 1/4 tank the throttle response will not be quite as good. I doubt this is just in my head because otherwise, I wouldn't have noticed it. It's a VERY subtle difference.
Typically with my car, I need to take the gauge reading and subtract a 1/4 tank from it to get the actual amount. For example, I fill it to the max which will put the needle about a 1/4 distance PAST the full mark. When it goes down to the full mark, I have 3/4 tank, and so on...
Typically with my car, I need to take the gauge reading and subtract a 1/4 tank from it to get the actual amount. For example, I fill it to the max which will put the needle about a 1/4 distance PAST the full mark. When it goes down to the full mark, I have 3/4 tank, and so on...
Thread Starter
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Joined: Oct 2007
Posts: 57
I always run premium gas in mine and I too notice that if I let the gas get around a 1/4 tank the throttle response will not be quite as good. I doubt this is just in my head because otherwise, I wouldn't have noticed it. It's a VERY subtle difference.
Typically with my car, I need to take the gauge reading and subtract a 1/4 tank from it to get the actual amount. For example, I fill it to the max which will put the needle about a 1/4 distance PAST the full mark. When it goes down to the full mark, I have 3/4 tank, and so on...
Typically with my car, I need to take the gauge reading and subtract a 1/4 tank from it to get the actual amount. For example, I fill it to the max which will put the needle about a 1/4 distance PAST the full mark. When it goes down to the full mark, I have 3/4 tank, and so on...
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Joined: May 2006
Posts: 1,855
From: Ohio
I am somewhat confused about this thread but, are you saying the car feels slower even though its 80lbs~ lighter? I never noticed this in my car, or did I when I had my 2.73's sometimes it would seem like it missed then take off but it only happend a handful of times in 20k miles. Who knows hope you get your car fixed 
Maybe some quarter mile times would settle this dispute, or even better a dyno, but that costs money.
Maybe some quarter mile times would settle this dispute, or even better a dyno, but that costs money.
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Joined: Mar 2006
Posts: 662
From: albany, ny
The only thing that can make it run worse would be lower fuel pressure. If the pressure is falling off then there is something wrong with the pump or the bucket, either of which is not normal. Check the fuel pressure when the tank is low on fuel. If it's not correct or is fluxuating then you obviously have a problem.
there is a lot of miss conception about fuel in here.
open you owners manual and read it and look for what octane it says to run and thats what you run. Changing the octane with out changing any other aspect of the engine like timing or compression will do nothing for you. 87 gas isnt any better then 91 and 91 isnt any better then 87. octne in a simple term is the antiknock properties and the rate at which the fuel burn. By anti knock it means it stablitiy under pressure and its resistance to preignite.
putting 91 in a car thats meant to run on 87 will do nothing noticeable if anything at all.
another possibility is if you keep buying you gas from the same place maybe their tanks are tainted with something. what ever it is the gas is lighter then the gas in the tank. when your gas tank gets low you start sucking up whats siting on top of the fuel.
Last edited by GRNcamaro; Oct 31, 2007 at 10:33 AM.
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Joined: Dec 1969
Posts: 4,950
From: San Diego, CA
And it kills me that people insist on talking when they don't know what they are talking about.
Our fuel pumps are in a bucket and run submerged in fuel ALL THE TIME. Even if there is only a half gallon in the tak the bucket is full. It makes NO difference how much fuel is in the tank. Even in applications that don't have a bucket the pump is still cooled by fuel because it runs through the motor.
The performance of the engine is the same no matter how much fuel is in the tank. It's in your head.
Re'
Our fuel pumps are in a bucket and run submerged in fuel ALL THE TIME. Even if there is only a half gallon in the tak the bucket is full. It makes NO difference how much fuel is in the tank. Even in applications that don't have a bucket the pump is still cooled by fuel because it runs through the motor.
The performance of the engine is the same no matter how much fuel is in the tank. It's in your head.
Re'
Registered User
Joined: Mar 2006
Posts: 662
From: albany, ny
also isnt it possible the fuel would cool down with its trip through the fuel lines?
Last edited by GRNcamaro; Oct 31, 2007 at 10:36 AM.
Thread Starter
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Joined: Oct 2007
Posts: 57
OMG.. Im tired of you guys telling me that it is in my head. I CAN FEEL A DIFFERENCE. If I notice my car not running as strong, I can simply look at my fuel gauge to see it below a 1/4 tank.
Fuel Pressure, Bad Stuff in the Gas, or Heat on the pump has to be the culprit here.
Fuel Pressure, Bad Stuff in the Gas, or Heat on the pump has to be the culprit here.
Registered User
Joined: Mar 2006
Posts: 662
From: albany, ny
Thread Starter
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Joined: Oct 2007
Posts: 57
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Joined: Apr 2004
Posts: 236
From: Charlotte, NC
If you think you're losing power then do what has been said already. Check fuel pressure when full and when getting low and look over the rest of the fuel system. You could even dyno it, then drain the tank down and dyno again to see if you're really losing power. The car shouldn't run any differently just because there's less gas in it. If anything it should be faster since it's lighter.
