MPG decrease / 02 Chevy 4.3L

[mechgo1977]

Had taken this in for a recall on the cap/rotor, since then the mpg has dropped from 25mpg to about 20mpg. Then about a month later I decided to change the plugs since it had 60k on it. Then I was at about 27mpg (really), for about 700 miles then it dropped back to 20mpg.

Any ideas?? other than paying the dealer $100 to plug it in.

[wrparks]

27 mpg!!!! I find that hard to believe unless you never go in the city and don't drive above 50 mph with a feather holding the gas petal down. Although if you can, I want your truck. My 4.3 gets about 20 mpg every fill up so your most recent numbers seem respectable to me.

Also, how are you computing your mpg? Don't trust the DIC or the gas guage method. The only reliable way is to completely fill the truck with gas and reset the trip odometer. Then next time you fill up divide the actual number of miles driven by the actual number of gallons put in shown on the pump. It's even more accurate to use the exact same pump to fill up both times because different pumps have different cut off points, but that is probably too anal retentive.

If this is what your doing, I would say you have one hell of an efficient engine on yours. Could be bad gas at one station?

Which cab/bed legnth do you have? Bed covers of some sort?

[mechgo1977]

The only time I mess around with checking the mpg is on the highway but I normally drive about 65-70 depending on the area.
I check the mpg the by the pump and miles on the truck.

It is a regular cab short box with a tonneu cover.

[wrparks]

Ok, I guess I can see you getting a bit better mileage than me with the short box and tonneau cover. I have been considering a cover myself. Do you have pre tonneau gas mileage, I'm curious how much that helped you. 27 is still amazingly high, but I'd say possible under ideal circumstances. I know GM rates the short box slightly better on fuel than the long box, I'm assuming b/c of the weight difference.

When was the last time the fuel filter was changed and how many miles are on the truck?

[mechgo1977]

Originally Posted by wrparks

Ok, I guess I can see you getting a bit better mileage than me with the short box and tonneau cover. I have been considering a cover myself. Do you have pre tonneau gas mileage, I'm curious how much that helped you. 27 is still amazingly high, but I'd say possible under ideal circumstances. I know GM rates the short box slightly better on fuel than the long box, I'm assuming b/c of the weight difference.

When was the last time the fuel filter was changed and how many miles are on the truck?

It has about 60k and probably due for a filter change. I had the tonneau cover when I bought the truck so really not sure how much it helps.

[Red Slilvy]

I have a 02 4.3 std cab short bed with a cover , K&N stock box filter, Gibson dual side sport cat back And a 5 speed and all I get is 21MPG. I seldom see 3K RPM. I'm looking for some low end power & better MPG. 20MPG isn't too bad.

[mechgo1977]

Originally Posted by Red Slilvy

I have a 02 4.3 std cab short bed with a cover , K&N stock box filter, Gibson dual side sport cat back And a 5 speed and all I get is 21MPG. I seldom see 3K RPM. I'm looking for some low end power & better MPG. 20MPG isn't too bad.

I forgot to mention that I have the K&N and have been running Mobil 1. I may have a Flowmaster installed next, they claim that helps. I have the automatic with overdrive and at highway speeds it runs about 1800 rpm.

[Red Slilvy]

At Highway crusing speed my RPM is just under 1500. So when I hit a good hill I need to shift to 4th. I've had several GM's with 6's but they were all straight 6's. I whish my v6 would pull as good as my 54' with the 235ci 6. I'm thinking of doing the LS1 fan setup with Nelson's harness to get back a little low end. Has any one had any luck with that setup.