Look for a book on how to rebuild your engine. Loss of power and decrease in miles per gallon are signs of a engine that's done.

 

Take the pallet of cinder blocks out of the bed.

 

Speed-Density can't compensate for engine wear that well, so a worn out engine and a new engine really wont be to different mileage wise. I doubt even the most worn out of engines could drop from 20 to 7 MPG.

Provided your valve lifters don't give out, and you have the updated heads, a 2.9 is a 200-300,000 mile engine, like the 4.0 OHV. My 2.9 with 146k still has 160 PSI compression on all 6 cylinders.

Black smoke at start up, and low power points to an injection problem, rather then something internal to the engine.

 

hey guys thankks for all the info, i have decied to redo the fule system, new pump injectors ext.. the truck runs good i dont think that motor is worn out it could deff run better but any. i will let you no how i make out i will start this project next weekend.

lead head i am goin to test the map today and will let you no how i make out later on today, thanks

thanks guys,steve

 

8 MPG, something is wrong with the computer sensors (AKA no closed loop).

Things to check.

Pull the codes, see what turns up.

1: check all vacuum hoses; even a small leak can raise havoc.

2: change the O2 sensors; they control the air fuel mix when in closed loop. If you have more than 30K on the o2, replace them, they get lazy (or fail) over time and they are inexpensive. They may not through a code or set the mill light.

3: MAP sensor, check the vacuum hose!! A leak or crack will cause a rich condition at the very least. Also have the sensor checked if you can.

4: thermostat, make shire the engine is warming up to operating temp, if not replace it! The engine needs to be at operating temp for the computer to go into closed loop.

5: coolant temp sensor (CTS), not the one for the temp gage, the one for the compute. If this sensor is bad the computer will think the engine is cold all the time and add more fuel.

6: fuel presser regulator, pull the vacuum line and plug it, start the engine and let it idle for a bit, if gas comes out of the vacuum port on the regulator it is bad.

7: check all the fuses, on a modern computer controlled car there are several fuses that supply power to the computer and sensors.
If one blows the vehicle may still run and drive! (But with problems).

Last but not least check the exhaust back presser, if it has been running rich for a while the cat might be plugged (or had a meltdown).

If you follow this list I think you will find the problem (or at least you can rule these components out).


Good luck and post back your results.

Tom Cat