Poor gas mileage

I have a 2000 z71 and have experienced poor gas maileage lately around 12 MPG. It was around 19 MPG . It started going bad when it wouldn't start after I came home and after about 20 minutes of cranking on it it started up and it hasnt done it since. I took it to the mechanic and he said that the fuel filter was plugged. I replaced that and still no better gas mileage. It sems to have lost some power too. I have a K&N in it and that is all the mods. Can someone out ther give me some ideas?

how is the transmission working? can you tell if it is going into overdrive for sure? how many miles?

juma

It is going into Overdrive just fine and shifts properly...I run about 60 MPH at 1600-1700 RPM. I have 55K miles on the truck. Just poor power and gas mileage.

Check the O2 sensor. Cliff

I have a 2000 K2500 that is doing the same thing. It starts fine when it is cold, but then you have to crank on it a little before it will start again.

The gas mileage is the pitts, I pulled a car trailer about 200 miles (100 miles loaded) and got 6.5 mpg.

I wondered about the fuel regulator, but it is dry in the vacuum port.

Will the 02 sensor cause this??

-slacker

do a fuel pressure test, if the pressure drops within a few minutes, climp the fuel return hose and do the test again, if the pressure doesn't drop its probably the regualtor

Hey everyone, I just got home and the damn truck wouldnt start again...i cranked on it and it would fire but then it would die as soon as it fired up....then after about 12 times cranking on it and about 10 minutes later it fired right up but it seems that at idle the truck started to idel real rough. You could feel it shaking but not real bad. Can someone help me out. There are no check enigne lights or anything when this happens.

Could take a look at your MAF sensor, may be dirty. What's the fuel pressure? Does it hold pressure after the pump shuts off? Do you hear the pump running when to turn the key on?

where in the hell is my MAF sensor?