OSU_METGRAD

Hey guys,

I'm brand new to the forum but I have a problem with my 2001 v-6 Silverado that I can't figure out. I'm not a good mechanic but I know some of the basics and here's what I do know...

In the last 8 months my gas mileage has dropped from 18/20 to sub-15/18 with no noticable difference is enginer power, performance. I've replaced the spark plugs, air filter, and fuel filter with no effect. I've ran injector cleaner through a couple of times with no effect either. I've had it in the shop and they hooked it up to their computer and couldn't find anything wrong with any of the temperature/O2 sensors. The only thing I know that isn't working properly is the check valve on the fuel tank, the fuel pump works fine but when it shuts off the fuel pressure drops off quickly. Once the truck is running it maintains a constant 60 psi pressure.

I do have 141k miles on it so I could understand perhaps a small drop in gas mileage but not something this drastic. I'll say again that I have noticed absolutely no drop in power/acceleration/etc. I don't think its a transmission issue b/c it is shifting fine, no lags in power anywhere, I'm truly at a loss.

Any help/advice/direction would be GREATLY appreciated.

Thanks, GO POKES!

maxxman04

check the trans fluid anyways. if it has any brown or orangish tint to it, change it immediately. any idea when the fluid and filter were last changed? auto trans do have a certain amount of slip rate, even new. the fluid does break down over time, unable to maintain the necessary pressure needed. this could result in lower mpg's without any notice in performance of motor or trans.

OSU_METGRAD

its been about 90K since I had the transmission flushed and I doubt the filter has ever been changed. I'll check on the color...thx

gotstylez

90k lol..i'd be getting it flushed!!!! we useally do ours withen the 40k mark..

OSU_METGRAD

Yeah, I don't deny it should of been quite a while ago... being a new college grad, finances have been pretty tight the last couple of years.

I'll work on getting that done. :-)

UH60sSuck

Do you have any kind of whine coming from under the hood?

therewolf

For my money, I'll bet it's the transmission filter. Especially with that mileage.

You may want to install a drain plug in your tranny pan when you do the job. It's only @12$, and money well spent, if you plan on keeping the vehicle.

Your engine is already working harder to move the tranny. I know of a couple older vehicles which had the tranny filter clogged so badly, they literally stopped moving.

How's your tire inflation? And how are your shocks?

OSU_METGRAD

No whine from under the hood.

I want to say my transmission pan already has a drain plug but I'll check it out.

I got new tires a couple of months ago so its not related to tire pressure and they're not oversized tires either. Shocks seem to be working fine...

gotstylez

just becuase they are new it doesnt mean they are low. since it says osu in ur name in guessing ur in ohio lol cold temps usally make ur tire pressure low

maxxman04

90k since last service?! yeah, def change fluid and filter no matter what.