Thursday, December 18, 2014

Gas tank, wheel bearing issues

Fill ´er up.
Fill 'er up. iStock

(MCT) -- Q: When I reach about a half tank of gas with my 2006 Hyundai Azera 3.8 engine, the gas gauge goes down to empty and the low fuel light comes on. Is there a sensor that controls the gauge or is there a problem with the fuel pump? If there is a sensor, can I replace it myself or should I take it to a mechanic?

-Michael Szwarc

A: Your Azera utilizes a fuel tank module consisting of the fuel pump and gas gauge sending unit. The sending unit contains a variable resistor and float lever. Differing fuel levels move the lever, resulting in greater electrical resistance with a low fuel level and less resistance when the tank is full. A faulty electrical connection is the cause of your gauge dropping to empty, because high resistance and bad connections go hand in hand. Since your symptom occurs only when fuel is at a certain level rather than at random times, it's safe to say the electrical fault is within the sending unit.

Combining both the sender and fuel pump unfortunately means one needs to replace the complete unit even though only one part is faulty. If your Azera has racked up 80,000 miles or more, the fuel pump is entering its twilight time, if that helps one stomach the $300-400 parts cost, plus installation. The fuel module is accessed by removing the back seat and then a thoughtfully convenient hatch in the floor. Book time for renewal is one hour. It's not a difficult job, but one needs to diligently follow published safety precautions/procedures because of fuel vapors entering the vehicle and liquid fuel directly beneath.

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  • If you are the sole driver and share my inclination to allow the fuel pump to enjoy a full life, you could simply punch the odometer reset button when the gauge reads half and use the miles accrued as a gauge supplement. I'd record the typical miles driven during the full to half gauge transition and figure about half of this would be a reasonable distance to fly blind before refueling.

    Q: I was shocked to hear my '07 Yukon required a new front wheel bearing at the tune of $485! What gives to make this such an expensive repair?

    -Victor Sanchez

    A: Similar to Michael's issue above, component integration was not your friend. The Yukon's front wheel bearings are integrated with the wheel hub and ABS wheel speed sensor, creating a $400 part instead of perhaps a $30 one. The non-serviceable hub assembly is a simple bolt-on arrangement, after removing the brake caliper and rotor. My assumption is this is a labor/cost saving strategy for vehicle assembly - and it seems GM cheaped out a bit on bearing quality. I've already renewed both left and right side hub assemblies on my HD2500 Silverado in less than 75,000 miles. I specified Timken aftermarket replacements, as they're my bearing company of choice.

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    ABOUT THE WRITER

    Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, Calif. Readers may send him email at under-the-hood(at)earthlink.net; he cannot make personal replies.

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    Brad Bergholdt McClatchy-Tribune News Service