why is my gmc jimmy four wheel drive v6 using so munch gas?

[elvis e]

could it be the COMPUTER or Control Margalo i got a new map seance but it does not help. i got another throlbody carb but it still uses $10 to go 25 miles it is burning rich any ideas?

 

[bandit_60]

are you sure you don,t have it locked in 4 wheel drive?

 

[Kabarkads]

Bring it to the GMC Service Center and they will try to adjust the computer box. If it is still fuel hungry then replace your car with diesel or hybrid.

 

[Molson02536]

What year is your jimmy???? You could have a bad fuel pressure regulator and it's leaking fuel in the intake manifold. Run the full fuel pressure test and post back pressures.
Here is the guide lines on testing.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.