4.3L Z code mileage??

[Gordon]

I have a 1993 GMC Safari with the Z code HO engine in it, 3:73 gears and 4l60e trans with stage 2 shift kit. It runs great has plenty of go-nads but it stinks like raw fuel every once in a while for no reason and has HORRID gas mileage... i'm talking like 400km/s to a FULL tank (and that's driving it nicely)

How many km/s are you guys getting on a tank?

What on earth is wrong with this beasty? I'm getting to the point where i'm gonna put a brick on the gas pedal and let the motor EXPLODE

I will say that the Z code motor goes like a bat though, it USED to get 24-26mpg in city now it might have 15 #-o

[potskie]

Doesn't sound to far off. My 93 never got better than 19MPG city and that's down hill both ways. It averaged 17.5 and Passed Emissions like a breeze too. that's with over 500,000 miles on it too. I would start by checking your fuel lines and the injectors for leaks first. Then maybe the 02 and temp sensors to make sure the ecm is going closed loop and not staying open loop and just dumping fuel into the engine.

[Gordon]

How do you "check" an o2 sensor or the temp sensors?

Its not showing me any codes as of yet.

[kings-x59]

Go to http://www.autozone.com to their repair guides. They have write-ups on how to test sensors for the '93.
Here's a link to the O2 sensor test.
http://www.autozone.com/az/cds/en_us/09 ... tm#hd1-1-2
One other thing you might check are the vacuum lines from the gas tank to the evap canister, and evap canister to throttle body. leaks in these lines will waft gas vapors periodically. Leaks in these lines will also create vacuum leaks, which I noted in the O2 sensor test write-up "confuse" the ECM into oscillating between full rich / full lean fuel delivery.

[astrozam]

I have a 1993 GMC Safari with the Z code HO engine in it, 3:73 gears and 4l60e trans with stage 2 shift kit. It runs great has plenty of go-nads but it stinks like raw fuel every once in a while for no reason and has HORRID gas mileage... i'm talking like 400km/s to a FULL tank (and that's driving it nicely)

How many km/s are you guys getting on a tank?

What on earth is wrong with this beasty? I'm getting to the point where i'm gonna put a brick on the gas pedal and let the motor EXPLODE

I will say that the Z code motor goes like a bat though, it USED to get 24-26mpg in city now it might have 15 #-o

I would tend to agree with you, 400km to a full tank (providing we are talking the 27 u.s gal tanks = 22.4 u.k gallons) is terrible mpg's,even with my 4.11's i'm still just over 600km to a tank (mostly hwy)

400km=249 miles 249miles/27 u.s gallons= 9.2 mpg u.s
400km=249 miles 249miles/22.4 u.k gallons = 11.11 mpg u.k (canadian)

600km=372 miles 372miles/27 u.s gallons =13.7 mpg u.s
600km=372 miles 372 miles/22.4 u.k gallons =16.60 mpg u.k

The highest mpg claim I have seen so far on this or A.S forum is 28mpg u.k
28 u.k mpg X 22.2 u.k gallons = 622 miles( u.s or u.k doesn't matter) = 1001km (highly doubtfull)
28 u.k mpg = 23.31 u.s mpg X 27 u.s gallons = 623 miles= 1002km

Hope I did the math correctly.LOL