Fuel Gage Issue

[907trac]

I was driving around town the other day and i looked at me gage and noticed it was at half a tank,which is ok and all.I drove a few miles down the street and the gage instantly goes under the red empty line.I thought the gage was bs'ing me so i drove around anyways with it like that for awhile.the next morning i wake up and start the truck and the gage line shoots just shy under half a tank,which is where it should of been...later on that day after work i turn it on again and it shoots over the full fuel line...drove it some more and it shuts off again....so i drive it to the gas station and fill it up.turn it on again and it shoots up to full fuel.....drive 100 miles and the gage still reads on the fuel line...plz help im sure its simple,and yes i have checked the fuses.

 

[bdmaash]

either a bad connection somewhere, or the fuel sender in the tank is faulty. It won't be a fuse.

Yes, it is simple if you can test the wire all the way from the tank to the instrument cluster, and drop the tank to access the sending unit which is part of the fuel pump assembly.

 

[manaen]

dropping the tank is not fun, but it's not impossible. Just make sure you run it low on gas before attempting the fix. More than likely it is a dead spot in the potentiometer for the gas gauge sending unit.

 

[ncranchero]

Maybe a bad connection, maybe a bad sender but read this little tutorial on the fuel gauge operation. I seem to having a slosh circuit issue since my gauge floats up and down as driving conditions change.

Fuel Gauge

The fuel gauge receives its signal from the fuel level sensor, part of the fuel pump module. Fuel level is determined using a variable resistance fuel level sender unit, with an approximate resistance range between 15 ohms ± 2 ohms at empty (E) and 160 ohms ± 4 ohms at full (F) on gasoline engines and between 8 ohms ± 2 ohms at the lower stop position and 140 ohms ± 4 ohms at the upper stop position on flex-fuel vehicles. If equipped with flex-fuel, the basic fuel level indication is the same except that the flex-fuel vehicles incorporate the use of a flex-fuel module. The flex-fuel module is a DC-AC-DC interface, used to prevent reactions created by the interaction of DC current with the fuel. The flex-fuel module is part of the fuel pump module assembly and is installed as an assembly.

The instrument cluster uses 4 different operating modes to calculate the fuel level:

anti-slosh (default mode)
key OFF fueling
key ON fueling
recovery
After a fuel fill up, the time for the fuel gauge to move from empty (E) to full (F) ranges from 2 seconds to 55 minutes depending on which operating mode the fuel gauge is in.

The default fuel gauge mode is called the anti-slosh mode. To prevent fuel gauge changes from fuel slosh (gauge instability due to changes in fuel sender readings caused by fuel moving around in the tank), the fuel gauge takes approximately 55 minutes to go from full (F) to empty (E).

The key OFF fueling mode (2 seconds to read empty [E] to full [F]) requires 3 conditions be met:

The key must be in the OFF position when refueling the vehicle.
At least 15 percent of the vehicle's fuel capacity must be added to the fuel tank.
The instrument cluster must receive a valid key ON fuel sender reading within 1 second of the key being put into the RUN position. The key ON sample readings are considered valid if the fuel sender reading is between 15 ohms ± 2 ohms and 160 ohms ± 4 ohms. If these conditions are not met, the fuel gauge stays in the anti-slosh mode, which results in a slow to read full (F) event.
The key ON fueling mode (approximately 90 seconds to read empty [E] to full [F]) requires 3 conditions be met:

The transmission is in park (P).
The key is in the RUN position.
At least 15 percent of the vehicle's fuel capacity must be added to the fuel tank.
In key ON fueling mode, a 30 second timer activates after the transmission is put into the park (P) position. When the 30 second time has elapsed and at least 15 percent of the vehicle's fuel capacity has been added, the fuel gauge response time is 90 seconds to read from empty (E) to full (F). When the transmission is shifted out of park (P), the fuel gauge strategy reverts to the anti-slosh mode. This mode prevents slow to read full events from happening if the customer refuels the vehicle with the key in the RUN position.

Recovery mode is incorporated into the instrument cluster strategy to recover from a missing fuel level message during a refueling event. Missing fuel level messages result from intermittent opens in the fuel sender or its circuits. Recovery mode (empty [E] to full [F] approximately 20 minutes) is initiated when the following 2 conditions are met:

The instrument cluster is in the anti-slosh (default) mode.
The actual fuel level in the tank is greater than what is being displayed by the fuel gauge.

 

[907trac]

im going to look through everything,i only noticed that it went bad/messed up after it dropped negative 50 degrees,think i might throw it in a garage for a couple of days and see if something dont come up

 

[onetwin69]

Just had this problem occur with my 2005 4.0L sport trac! Been a costly experience for me. Off to the junk yard I go for parts this weekend.
Good luck with your repairs.
AF

 

[Pjibs]

I sort of have a similar problem when I first start up my trac in the morning but then it figures itself out and holds steady until I turn it off. When I run close to "E" the stick will dip up and down for a few minutes and then settles out. I don't know what the deal is, but it has gotten me some close calls for almost running out of gas, haha.

 

[onetwin69]

Fuel ga issue

Hi there. Good luck with that. I just spend $450.00 on the sending card and unit. That wasn't the issue. The issue is in the connector. The number is a connector (DC-AC-DC converter). Ford (in Canada) wants $250.00 for the connector. I can get one online for around $50.00. I have diagrams if anyone needs them. Connector cable # = 4L2Z-9S277-CA
Just trying to help anyone having the same fuel line / ga. issue, so they don't get hosed like me. (no pun intended!)

 

[Sined]

Just a question can you have one connector for f150 5.4l 2008 flex-fuel? you are only 1 man say you find this in canada? i from Quebec...thank you for your answer!!!