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Discussion Starter #1
i'd like to know what i'm getting to the gallon. it seems like it's drinking it like a fish. i've seen the needle gauges from jc whitney but my question is could you take a digital one out of a overhead panel in newer model car or truck and make it work?
 

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The only way to accurately calculate mpg is to fill the tank up at a pump, drive it like you regularly do, and once you need gas again, go to the same pump and fill it up again. Then divide how many miles you've driven by how many gallons you used. It's very simple to do.
 

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Discussion Starter #3
so there is no way you could take the guts out of a car that is equipped with one and mod it to fit our escorts?
 

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You can get a fuel monitor, which just shows you how much fuel is being pumped.

Doesn't really do you a whole lot of good. I just do a simple math calculation.

We've got 10 gallon tanks (at least mine is), I take however many miles I've driven divided by 10. But if I stretch it and go way past the Empty line I divide by 11 because of the reserve.
 

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Most of the newer vehicles (someone correct me if I am wrong) use some sort engine vacuum readings to determine your mpg. My dad said back in the 70's a friend of his had a car the had an analog gauge for mileage. All it was was a vacuum gauge. The more vacuum the lower the mileage.
 

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white-lightning said:
Most of the newer vehicles (someone correct me if I am wrong) use some sort engine vacuum readings to determine your mpg. My dad said back in the 70's a friend of his had a car the had an analog gauge for mileage. All it was was a vacuum gauge. The more vacuum the lower the mileage.
I heard it's smart gerbils that smell the vapors and then calculate the remaining fuel, then army ants send the readings to the gauge by morse code. 8O

Back to the original question, are you trying to determine your gas mileage, or fix your gauge? If the gauge is acting up, it's either a bad voltage regulator on the instrument panel, and/or the sending unit in the tank is failing.
 

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Discussion Starter #7
i dont really think my gauge is bad. i guess it kinda floats. i think im getting about 200 miles to the tank. it should be getting in the 300 range right?


leaning towards that vaccum line on the throttle body being plugged. i wonder if the ecu is throwing more fuel than it needs.

ha. plus i love watching the numbers change on the overhead mpg gauge in the truck. :p
 

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Newer vehicles get the MPG reading from the signal read out by the MAF sensor I think so you wouldn't be able to use it on your car. As someone else already stated the easiest way to figure your mileage is to divide the miles driven by the number of gallons used. You can use a vacuum gauge to help you get better mileage though by driving in a manner that keeps the engine vacuum at it's highest reading possible. I have one in my '88 Pony and am getting 41-45 MPG most of the time. If your car was OBDII you could buy a Scan Gauge 2 for about $160, that hooks directly into the OBDII port that would give you instant MPG readings along with several other useful pieces of information about your car and also is capable of scanning the ECU for codes.. If you are only getting 200 miles from a tank of gas you need to check the ECU for codes, because it should be doing much better than that. Has the 02 sensor been changed lately? A bad 02 sensor will cut mileage usually by 25-35%. How long since it had a tune up? Have you checked for vacuum leaks? Have you checked to make sure you don't have a brake dragging or a wheel bearing that is keeping the wheels from rolling freely?
 

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Discussion Starter #9
wheels roll freely. i'd say it has been a while on the o2 sensor. is that vacum gauge the one like jc whitney sells? and there is no check engine light.

oh i still havent figured out where the vaccum line goes from the bottom of the throttle body!
 

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Spiffy said:
You can get a fuel monitor, which just shows you how much fuel is being pumped.

Doesn't really do you a whole lot of good. I just do a simple math calculation.

We've got 10 gallon tanks (at least mine is), I take however many miles I've driven divided by 10. But if I stretch it and go way past the Empty line I divide by 11 because of the reserve.
For '88.5-'90 years Ford only spec'd using a 13 gallon tank. I know...I thought mine was a 10 gallon, too, until I took it out and looked at it. Definitely a 13.
 

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The vacuum line on the bottom of the throddle body should go to a tee (should be right behind the throddle body) and from the tee one of the lines goes to one of the orfices for the PCV system and the other line goes to a vacuum connection that is mounted to the left had strut tower. If that vacuum line is not hooked up that's probably why your mileage is so low. You can use any type automotive vacuum gauge. There are some available that are made up like an oil presure gauge or temp gauge and has a light in them for night use. I'm just using a regular mechanics vacuum gauge in mine.
 

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UnexplodedCow said:
Spiffy said:
For '88.5-'90 years Ford only spec'd using a 13 gallon tank. I know...I thought mine was a 10 gallon, too, until I took it out and looked at it. Definitely a 13.
I think the owners manual for my '88 Pony says it has a 12.9 gallon tank, but I have put as much as 14 gallons in one time. It was very very low, low enough the engine was sputtering and I filled it completely to the cap.
 

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My first supra had a "trip computer". It basically calculated MPG by how often the injectors pulsed. Would read anywhere between 0 (WOT) and 50+ (coasting down hill). But the most accurate way to do it is to fill your tank, just to where the pump auto-stops. Drive around for 1/2 or 3/4 of your tank, fill back up to the top. Take how many miles you've driven, ie: 135 and divide by how many gallons went into the tank, 4. So tap into your abacus or whatever other math device you use. 135/4. And you get 33.XXmpg. That's what I'm getting with my 91EGT.
 

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Well, last week I drove about 600 miles to/from work (yup, sucks), and I was driving it like a mofo...90 was the standard cruise speed. Math determined ~36 mpg. I can't complain :p. Plus my gas gauge has decided to become horribly inaccurate. I have nearly half a tank left when it's reading almost dead empty.
 

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At one point, when I actually had an owner's manual, I read that these car either have an 11 or 13. Pretty much it was the manual Pony's that had the 11, which was termed gas miser. Though my recent Pony part out had a 13 gallon tank.

You need to remember that a lot of liquid can fill the filler necks. And the fact that none of the cars I've had (have) read the same. There's always a big difference (2-3) in gallons when I fill up, even when the car is on e. Some run for a day on e, others spit and sputter just above e.

The instant reading thing is a joke anyway. You go from 99 mpg coasting down a hill to 1 tramping the gas up a hill. It should be the overall mpg that matter anyway. Which you need to the math when you fill up.
 

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Discussion Starter #16
FordMan59 said:
The vacuum line on the bottom of the throddle body should go to a tee (should be right behind the throddle body) and from the tee one of the lines goes to one of the orfices for the PCV system and the other line goes to a vacuum connection that is mounted to the left had strut tower. If that vacuum line is not hooked up that's probably why your mileage is so low. You can use any type automotive vacuum gauge. There are some available that are made up like an oil presure gauge or temp gauge and has a light in them for night use. I'm just using a regular mechanics vacuum gauge in mine.
i'm not sire if we are talkiing about the same line ford man. the line i speak of is althe way under on the very bottom of the throttlebody. and the tree on the firewall is plugged on one outlet.
 

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Same vacuum line, there's only one that goes to the throddle body. It connects to the bottom left side of the throttle body, goes to a "t" then the lines coming off of the tee, one goes to one of the orfices for the PCV system and the other goes to a vacuum connection on the left hand strut tower. There are two connections on the strut tower it goes to the bottom connection.
 
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