This is not my vehicle, it's my Dad's. But anyway, he has a 2000 Silverado with the 5.3. He used to get 23 mpg hwy and 17 in town. Now, NO MATTER how he drives, he gets 17. Even towing his boat, 17 mpg. He wants to know what could possibly be wrong with it. Mileage is under 50k I'm sure. I haven't looked in awhile. He said he brought in for an oil change and since then the mileage has been ****. Anyone have any ideas? It could probably just use plugs/wires, but I wanna see if anyone can come up with some ideas.

TIA guys.

 

That's strange...

How's the fuel filter?

 

It is very strange. Fuel filter as far as he knows has not been changed. But you would think the truck would run pretty poorly. He says it still has the same get up and go like it used to. Usually a poor fuel filter = poor performance, not the same. I'm not sure what to think.

 

Okay...

Man, I'll have to think about this one for a bit.

 

Leave it to me to bring up the hard questions.

I think it could probably use new plugs/wires. I don't think those have been changed either. I know it wouldn't hurt.

 

What oil and filter did they put in. Is it the same type of oil that he has been using. If he used to run Synthetic and they just but regular oil that might be messing with the efficence of the engine causing it to drink for gas. Just a thought. or if they used a no name crap brand of oil instead of penzoil or something like that. Just my 2 cents.

 

Not sure. I'll hafta look into that. I believe it's received dino oil it's whole life. It's always been dealership oil changes. I'm not sure if they put in Synthetic or not. I doubt it.

 

Fuel pump could be acting squirrely....wouldn't be the first slightly used silverado/tahoe to start puking one up.

 

Bought brand new. Thanks for giving an idea, but I don't think it's the fuel pump. Along with what I said about a fuel filter, I think performance would drop. Performance is still there, gas mileage is not. I'm leaning towards plugs/wires. I'll probably change those out for my pops and I'll get back to ya'll on here.

After typing this, I just got to thinking. Could it possibly be fuel pressure regulator? Are those known to going out/haywire on these things? I know when those go out they can either cut the fuel out or give too much. My dad being the anti-computer-in-cars kinda person, thinks it's the pcm messing up. Who knows. Keep the ideas coming guys, it's giving me a few directions to go in.

 

I Have A G/m Problem Too Mine Gets 15-17 Mpg On A Good Day I Drive 80-90 Miles A Day I Have A 2000 4.8 With 75,000 Miles And I Know Guys That Have Trucks With 5.3 With More Miles Getting Better G/m Than Me