Fuel guage vs range
Thread Starter
Racer
Joined: Mar 2005
Posts: 314
Likes: 0
From: Mile Hi Colorado
Fuel guage vs range
Trying to fix fuel guage issue....added a can of BG44k, still in progress. My question is, the fuel guage shows 3/4 and the range shows 85mi. On a stock `98, what is the scale of range to guage? Does 85 miles on the range equal 3/4 tank? Thanks for any comments help...
Instructor
Joined: Nov 2005
Posts: 222
Likes: 0
From: Edgewood Maryland
Trying to fix fuel guage issue....added a can of BG44k, still in progress. My question is, the fuel guage shows 3/4 and the range shows 85mi. On a stock `98, what is the scale of range to guage? Does 85 miles on the range equal 3/4 tank? Thanks for any comments help...
Something is definitely wrong though, as I can go almost 100 miles on a 1/4 tank (driving nicely of course)
Someone more knowlegable than me will probably be able to give you a better answer though.
Good Luck
Racer
Joined: Sep 2006
Posts: 389
Likes: 1
From: Roswell GA
Trying to fix fuel guage issue....added a can of BG44k, still in progress. My question is, the fuel guage shows 3/4 and the range shows 85mi. On a stock `98, what is the scale of range to guage? Does 85 miles on the range equal 3/4 tank? Thanks for any comments help...
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
Trying to fix fuel guage issue....added a can of BG44k, still in progress. My question is, the fuel guage shows 3/4 and the range shows 85mi. On a stock `98, what is the scale of range to guage? Does 85 miles on the range equal 3/4 tank? Thanks for any comments help...
Here's what I do.
The gas tank is 18.5 gal capacity.
Let's say you drive 135 miles, and the "Range" says 198 miles.
Let's say the MPG on the DIC says "18.0 MPG".
The number of gallons used = miles driven/MPG = 135/18.0 = 7.5
The number of gallons remaining = Range/MGP = 198/18.0 = 11.0
The sum of those two must equal the tank capacity = 7.5 + 11 = 18.5
If the sum isn't close to the full tank capacity, the something is wrong with the gas gage (more likely) or MPG calculator on the DIC (unlikely).
On my Z06, the sum calculation will usually be +/- 0.5 gal max from the full tank capacity of 18.5 gallons. If it starts going way beyond that, the sensors need some fuel cleaner in the tank.
Remember that you must reset the MGP and Trip Meter on the DIC to get accurate results.
Melting Slicks
Joined: May 2000
Posts: 2,498
Likes: 4
From: Brentwood TN
Get ready for the indicated fuel level to drop to zero. Trust the range indication. When you next fill up, put is a couple of bottles of Techron BEFORE you fill the tank to be sure it gets over into the passenger side tank. Do this for the next two or three fillups and it should clear up the hanging fuel level sensor in the passenger side tank. This is a known common issue with C5's that are (1) not driven a lot
and (2) sit for long periods of time with a half tank of fuel or less as indicated on the gauge.If you have Chevron or Texaco stations nearby, fill up with either as it contains Techron. If you can't find Techron, use Sea Foam which you can find at most auto parts stores.
Charlie
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
Melting Slicks
Joined: May 2000
Posts: 2,498
Likes: 4
From: Brentwood TN
Anyone know for sure about whether there are two systems or only the one?
Charlie
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Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
I'm not sure but I think the two sensors operate on different systems. I think the range indicator resets at fillup and the circuit has a "totalizer" in it that measures how much fuel was pumped to the engine and for early models how much came back and subtracts the difference from 18.5 gallons. The fuel gauge works off a potentiometer that can get crud buildup on the working surface when it is not submersed in fuel for long periods of time. At some point the float reaches a "clean" part of the potentiometer (usually at or near zero) and then it works again and sends that "surprise, surprise you really don't have as much fuel as you thought" message.
Anyone know for sure about whether there are two systems or only the one?
Charlie
Anyone know for sure about whether there are two systems or only the one?
Charlie
I know the Range does not reset when you fill-up. The Range will reset when you reset the MPG via the DIC.
I think the Range value is determined by how much fuel is in the gas tank as determined by the fuel sensors in the tank. So if the sensors are screwed up, so is the Range value. I almost ran out of gas once because of this.
However, the MPG value will stay accurate if the fuel gage goes nuts because that is calculated by the fuel volume being used by the injectors and the distance traveled during that time. So get use to how many miles you can go on a full tank while getting XY.Z miles per gallon.
Last edited by ZeeOSix; May 24, 2007 at 09:23 PM.
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
This tells me that the Range is calculated by using the fuel sensors as a measure of how much gas is in the tanks. If the gage sensors go crazy, the Range value will be messed up also.
One thing that is easy to do is as a "backup Range calculator" of sorts is to carry a small calculator in the center consol. If you always fill the tank (18.5 mpg capacity) and reset one of your trip meter, then you can always manually figure out how much gas is left by using the formulas below.
Gas Left = 18.5 - (Trip Miles/DIC MPG)
Remaining Range = Gas Left x DIC MPG
Example:
Trip Miles = 185
MPG = 21.5
Gas Left = 18.5 - (185/21.5) = 9.9 gallons
Remaining Range = 9.9 gal x 21.5 = 212 miles
Last edited by ZeeOSix; May 25, 2007 at 02:44 AM.
