Question about 1997 Jeep Wrangler

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My 97 wrangler 2.5L is having a issue that burns a lot of gas has black smoke out the tail pipe and is slugish on take off and has a spirt of energy when it gets to 3200 rpm. any ideas? I have replaced the map sensor, 02 sensor many times.any help would be great. thanks

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You may have one of two possible problems - either the fuel regulator is not working properly or the mixture control on the intake is not functioning - the fuel regulator is vacuum controlled and if the diaphragm leaks it will feed excess fuel, what is happening at 3200 is the engine at that point is running fast enough to burn all the fuel delivered, at lower speeds it cannot - thus the black smoke.
If the mixture control is dirty it may stick due to carbon buildups and deliver too much fuel. Usually idle problems exist if the control sticks.
The fuel rack is located at the top of the engine and has a long pipe with a round pot and a vacuum line leading into it. If the vacuum line is removed and fuel leaks out - it is defective.The idle control is held in place with screws at the front of the throttle body (where the air cleaner pipe fastens) - if cleaning this - ordinary carb cleaner can be used - take care not to rotate the plunger when cleaning. A third possibility is that the computer is either defective or not calibrating the fuel delivery properly, potentially it is not reading the rpm sensor or the throttle position switch data. You might also check for vaccuum leaks - this is indicated by a hissing sound when the engine is running - if a line has fallen off or broken, due to increased airflow - the computer will automatically compensate by delivering more fuel.

Posted on Oct 02, 2009

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Sounds rich. fuel pressure ok? pressure regulator ok? take the vac hose off the fuel pressure regualator and be sure no gas comes out of hose. if it does, replace it.

Posted on Oct 02, 2009

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