When when I did all the easy stuff like O2 sensor, plugs, wires, rotor cap & button and nothing worked, I took it to my mechanic. He diagnosed the problem and replaced the fuel pump. I suppose it's as easy as loosening off the fuel line on the tank side of the filter and turning the ignition key to 'ON'. The pump 'should' start pushing gasoline out in a full, steady stream. If it's only a trickle or an inconsistent stream, then you can be pretty sure its the pump. I would do this test with the vehicle 'overnight cold', so everthing is cool and no chance for an accident with the raw fuel.
Part II was that when I got the pump replaced and the motor running strong again, I found out I had a serious fuel leak somewhere around the engine. Gas fumes were very strong. I could barely drive it because the fumes were so bad. Took it back to the mechanic and turned out there was a leak in the pulsator. That's a device that evens out the fuel flow by taking out the intermittent fuel flow pulses caused when the injectors snap open and closed. Evidently, there was no 'leak' there before the pump replacement, because the engine was drawing all the fuel it could get from the fuel delivery system and no extra could leak out.
The system was probably running lean on a lot of occasions, as a result. I received some erroneous O2 sensor-related codes before the pump replacement. A lean running condition can also melt engine components.
However, I have had no problems in this area since I had the pump replaced.
Mike in AR
