Poor MPG's: Car Runs Very Rich - Pontiac G6 Forum
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post #1 of 3 (permalink) Old 08-13-2014, 07:20 PM Thread Starter
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Post Poor MPG's: Car Runs Very Rich

2007 G6 with 3.5L V6, used to get about 30 MPG's, now only getting 20 MPG's. The car has 78,000 miles on it and it runs very very rich, so much that you can smell fuel when you pop the hood. Just wondering if there is something with the injectors causing this or is it just due for a major tune up despite the owners manual saying 100K tune ups?

Considering Replacing:
Spark plugs and wires
02 sensor
PCV Valve
(Already replaced air filter)
And doing a fuel injection service.

Any thoughts or suggestions would be greatly appreciated. Thanks in advance..
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post #2 of 3 (permalink) Old 08-17-2014, 12:01 PM
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Not sure about your current issue but if the car is over 5 years old (2007 says it is) then the coolant should be drained, flushed a couple times with distilled water, and refilled with new coolant. It's only good for 5 years (or 100,000) miles. I changed it on my 2008 back in the early spring at around 68,000.

I'm not sure about the 2007 but I don't think the 3.5L has a PCV valve that is replaceable.

You could do the spark plugs (make sure proper gapping). I haven't done it on mine yet at 71,000 this is a cheap fix though not quite as easy as it was on the wife's 4 cylinder 2008 Vue. Maybe it would help your issue? Plus it depends how long you expect to own this car.

Any check engine light on? Scan it to see if anything comes up. You may have a leak in the fuel system somewhere.

2008 G6 Dark Gray Metallic SE V6
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post #3 of 3 (permalink) Old 08-08-2015, 09:16 AM
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These 3.5 V6's are dogs on gas anyway. Similar to the old 4.3 V6 that GM made. I opted for it for increased power, but I should have considered a 4 banger.
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