Gas light coming on at quater tank??

[RedRubyPearl]

hey guys im having a major issue with my I35 my gas light comes on at quater tank then I get a straange rattle coming from underneath the car only after the gas light comes on between 1000-2500 rpm please help me find out the isssue
thanks in advance

[loystock]

I'm not sure if the rattle is associated with the Low Fuel Light. It might be due to loose hanger/support for the exhaust system or related heat shields.

Do you really want to resolve the Low Fuel Light illumination at a quarter tank of gas? It can get complicated and there is a fire hazard. I personally don't let the fuel tank go below a quarter to prevent fuel pump starvation (and cavitation) as well as minimize the possibility of corrosion in the fuel tank (which can be troublesome). The Low Fuel indicator is part of the Combination/Unified Meter Control Unit and receives signal from the Fuel Level Sensor. The Fuel Level Sensor is mounted together with the Fuel Pump and Filter inside the fuel tank. The Fuel Level Sensor resistance varies as a function of fuel level - @ 5 ohm at FULL tank; @ 32 ohms at 1/2 tank; and @ 80.1 ohms with EMPTY tank (though reserve is usually 2 gallons or more). So it's possible that the sensor is out of calibration/spec or there could be a dirty/corroded connector between the fuel tank and combination unit, resulting into higher than normal resistance that trigger the Low Fuel indicator.

So let me know if you really would like to address the Low Fuel Level warning or not.

[RedRubyPearl]

wow you give great information thanks alot..I have a servicee engine soon light on which code reads back to some type of corrision or build up in my gas tank causing me to have these issues..I would really like to resolve the issue as a whole

[loystock]

You have to provide the trouble code. Depending on the extent of corrosion, it may require special treatment chemicals or even replacing the fuel tank. Keeping the fuel tank close to empty most of the time, especially if one lives in a humid area, will allow rust to set in causing lots of problem - hard starting, plugged injectors, backfiring, etc.