92Stepside

Good point. I may not be going into overdrive. cruising at 90kms im still reving at around 2k+ i think. i'll check that out later, it should be lower in overdrive no? i'll have to go out today and test this out with the time and such. what vacume lines would i be looking over? what do they look like, and where are they?

Im not sure if i constantly have dirt in my brakes. but if im coasting down a hill with a barrier beside me. i can hear like a scratching from the rear brakes. like dirt/mud in them. do you think they could be rubbing? how do i adjust that?

thanks, Mark

Blindsight

90km/h is about 56 mph; so you should be doing a decent bit under 2000 RPM, for sure. Even with my 4.10 gears (awful for gas mileage) I am around 1800 RPM at that speed (56mph/90km/h).

Did you have a chance to determine what gears you have yet?

92chevysilvy

another way to determine your gears is to look in the glovebox at all the codes. I beleive that it should be a GT4 code on the third line down about 4 from the left. GT4 means 3:73 gearing, so if you don't have that code, you have different gears

Flying Low

Based on your description of youir driving habits your milage seems typical.
Check your gear ratio; that with oversized tires can drastically effect performance.
Is your odometer off? check it against the mile markers on the highways. If it reads low then your tires may be tall enough to make you think you are dragging a anchor.

92Stepside

i havent checked the gears yet, but i have a feeling the rear brakes are dragging, but not dragging very much, becuase she does good, but you can hear it. the tires are 285/75/16R. same hight, but wider. and about 50% thread. non agressive all terrains. but the mileage suffered before the lift and tires. I took off the bumper valence(sp?) could that effect mileage signicantly? my spedometer is off about 5km+- i do beleive.

I tested the overdrive however, and it seems to be good today, but somedays mabey it isnt.

i read about people getting in the 20mpg rang with tbi. this is sad now. I might convert her to a carb

tire air pressure is high. the rear end does wine how ever, we think its going, and i just thought of this just now. it'll whine when you hit 70km'h a buddy told my it could be the crown and pinion or something. and the tranny clunks when i shift into gear. and appearently its got under 10k on it...

im going to buy a throttle body spacer soon to pick up some mileage. this is stupid. my brothers 79 350carb with 35" boggers and 7" of lift gets better mileage.

also, under the dash, one day after driving i noticed a little box hanging down, didnt look stock, and had a sticker that said, for automatic transmissions only. the truck did have a trailer brake system hooked up. could this be for that? or a transmission controller or something...?