Gas mileage change/no "get up"

[Jeremy Morphis]

I have a 2015 Silverado 2500hd gas, 6.0

My truck has 30,000 miles. I have always gotten 16-18 mpg on the highway (70mph). The last week, I can't get above 9mpg on the highway (70mph), even going downhill. Also, may be my imagination, it seems that I have lost some power. The truck feels like I am pulling a trailer or have a heavy load in the back. Any ideas?

[SouthernSilveradoGuy85]

The first thing that comes to mind and doesn't cost much would be a new air filter. I could be wrong though, but just a thought.

[HeliMark]

The first thing that comes to mind and doesn't cost much would be a new air filter. I could be wrong though, but just a thought.

Also add, is all the normal maintenance up to date. Fuel filter, plugs. See if any codes have been thrown. And last, maybe bad gas? Did this start just after a fill up?

 

Mark

 

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[SouthpawHD]

I would look at what the previous posters said, air filter and fuel filter.

 

If you are not sure what to do, you are under warranty so take it to dealer and have them double check some things.

[newdude]

No fuel filter on these gas trucks. GM hasn't had an inline filter on gas trucks since 2004.

 

Any codes, check engine light, etc? I'd be taking it in to the dealer asap.

[rocnrol]

E-brake?

 

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[GMCustomerService]

I have a 2015 Silverado 2500hd gas, 6.0

My truck has 30,000 miles. I have always gotten 16-18 mpg on the highway (70mph). The last week, I can't get above 9mpg on the highway (70mph), even going downhill. Also, may be my imagination, it seems that I have lost some power. The truck feels like I am pulling a trailer or have a heavy load in the back. Any ideas?

Hi j-mo,

 

We see that you are seeking the input of other forum members, and would like to offer our assistance as well. If you would like to discuss your situation a little more in depth, please know that we are only a private message away. Our team would be more than happy to assist any way that we can.

 

Thank you,

 

Bret B.

GM Customer Care

[Colossus]

There is a fuel filter in the gas tank. It's part of the fuel sending unit. I doubt it would be the air filter. You'd be setting MAF sensor codes by the time a filter became plugged enough to cause issues with engine performance.

[Colossus]

Sounds like you got a bad tank of fuel. Run it down and then fill up with some good fresh fuel from a top tier station (if you don't already fill up there. Even they can get a bad delivery of fuel from the terminal, or something washes down into the underground tanks at the gas station) and maybe add a can of BG44k to it as well, I really like the stuff. I use it twice a year. Not only does my repair facility use it, but so does my dealer service department, made me smile when I saw a service advisor recommending it as well as a professional fuel system cleaning to a customer who had brought her 15 year old Saturn in for performance issues.

https://www.bgprod.com/catalog/gasoline-fuel-system/bg-44k-fuel-system-cleaner/

[1982]

Was this problem ever fixed? I've got the same issue. I've seen a few other people do too and no one has posted if they got it fixed. I'm gonna go to the dealer and have a backpressure test done. Don't know what else to do.

[gearheadesw]

What does it do, or not do? Just bad fuel milage? Any pinning, surging, coughing like it's running out of gas? Fill up with some premium gas now and see if it changes anything.