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Fuel gage goes up and down - 2007 Chevrolet TrailBlazer SS

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It is more than likely a bad sending unit in the tank. Chevy is known for their gas gauge problems. :)

Each Chevy my family has owned had a similar problem.

Posted on May 26, 2011


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Posted on Jan 02, 2017

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HI, this is a malfunctioning sending unit that is located inside he fuel tank. this sending unit, transfers a Resistance signal to the gauge, in return, allowing you to see how much fuel is in the tank. if this mechanism becomes corroded or, damaged, this will cause the symptoms you are experiencing.

This damage is usually caused by fuel deposits left behind overtime. the modern day fuel we use can destroy sending units because of all the detergents and, nitrogen cleaning agents put in the fuel at the refinery. this is goo for cleaning out the rails and fuel injectors but, it usually can hurt the sending unit mech at the same time.

The fuel gauge sending unit is attached to the fuel pump Assembly. you will have to remove this assembly from the tank to replace it. the tank has to be lowered as well.

Posted on Jun 18, 2009

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SOURCE: fuel gage not working

The sending unit is bad and it is internal to the fuel tank. Does not appear to be available separately but only available with the fuel pump as a complete unit. Bad news... it is quite expensive. Two part suppliers I've checked run from $286 to $321 (depending on the warranty), plus you'll have to drop the fuel tank to install it or pay to have it done. Might be a tough decision to decide if it's worth repair or just to live with it.

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Posted on Jun 30, 2009

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