Gas Tank question

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Gas Tank question

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Chevrolet Forum >> Chevy Trucks, Vans & SUV's >> Tahoe >> Gas Tank question

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Gas Tank question - 9/6/2008 11:31:27 AM

joeysworld

Posts: 15
Joined: 9/6/2008
Status: offline

1999 Tahoe 4 door 4x4 5.7 /auto

In the very back of the gas tank, at the very top of the slope, near the filler/breather: What is that plug in for?

Post #: 1

RE: Gas Tank question - 9/6/2008 12:41:43 PM

in2pro

Posts: 429
Joined: 4/20/2008
From: Austin, Texas
Status: offline

On my 97 it was a vent tube, see attched pic

Thumbnail Image

Attachment (1)

(in reply to joeysworld)

Post #: 2

RE: Gas Tank question - 9/7/2008 11:31:18 AM

joeysworld

Posts: 15
Joined: 9/6/2008
Status: offline

Heres a pic...

http://i271.photobucket.com/albums/jj143/joeysworld69/gastank002.jpg

(in reply to in2pro)

Post #: 3

RE: Gas Tank question - 9/7/2008 12:21:28 PM

jackyshaikh

Posts: 88
Joined: 5/1/2008
Status: offline

Its Fuel tank pressue sensor.what it does read below.

The fuel tank pressure (FTP) sensor is a 3 wire strain gauge sensor much like that of the manifold absolute pressure (MAP) sensor, however this sensor has a very different electrical characteristic due to its pressure differential design. The sensor measures the difference between the air pressure, or vacuum in the fuel tank and the outside air pressure.
The sensor mounts at the top of the fuel tank sending unit. A three wire electrical harness connects it to the control module. The control module supplies a 5 volt reference voltage and ground to the sensor. The sensor varies a voltage between 0.1-4.9 volts. When the air pressure in the fuel tank is equal to the outside air pressure, such as when the fuel fill cap is removed, the output voltage of the sensor will measure 1.3-1.7 volts.
When the air pressure in the tank is 4.5 inches Hg (1.25 kPa), the sensor output voltage should measure 0.3-0.7 volts.
The sensor voltage will be approximately 1.5 volts when the fuel tank pressure is equalized with ambient pressure. The sensor voltage increases to approximately 4.5 volts when a vacuum of 14 inches Hg (-3.75 kPa) is detected.

(in reply to joeysworld)

Post #: 4

RE: Gas Tank question - 9/7/2008 3:24:38 PM

joeysworld

Posts: 15
Joined: 9/6/2008
Status: offline

Would the fuel tank pressure sensor effect the fuel gauge if it is bad or going bad?

(in reply to jackyshaikh)

Post #: 5

RE: Gas Tank question - 9/8/2008 6:18:32 AM

jackyshaikh

Posts: 88
Joined: 5/1/2008
Status: offline

It should not affect on fuel gauge as it is designed.the fuel level sensor only gives wrong reading,when there is high resistance in ceramic resistor card.

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Post #: 6

RE: Gas Tank question - 9/10/2008 7:51:11 AM

joeysworld

Posts: 15
Joined: 9/6/2008
Status: offline

Sorry for the late reply.

Thank you for the info on the fuel tank pressue sensor!

I had an issue with my fuel gauge, but resolved it yesterday when I installed a new fuel pump/sending unit, and cleaned up the ground wire.

Thanks again.

(in reply to jackyshaikh)

Post #: 7