My truck has been running rich for a while. i have looked every where for a solution, with no success. it is running like it is missing a cylinder and exhaust smells like fuel. this is what i have done so far.
1. the spark plugs and wires look new.
2. the fpr looks new and is bosch. with no fuel in vacuum line.
3. the egr looks like it is working, but could not pull it all the way off due to the exhaust input pipe.
4. the injector are working correctly and are ticking right.
You may want to check the PCV valve. If it is stuck open, your "Metered" vaccum leak, is now uncontrolled (even a bit more open even @ idle). I have many posts on how to check the O2 sensor allowing for an easier way of diagnosing a RICH or LEAN condition, if you have a good Digital VoltMeter.
Have you pulled codes? There is an easy way, that only requires a jumper wire and an Analog voltmeter. Try Ford Fuel Injection or read the Sticky @ the beginning of '87-96 Forum.
Another possibility is the thermactor system. Let us know what your results are and we'll try to help as much as possible.
well i just checked the spark plugs myself, my mechanic said he checked them, and found that they were not torqued right and that they looked like they did not have very much spark. so i took the coil off and lo and behold it is stock from 93! so i am going to get it tested and see what happens. could that cause it to act like it is running rich when it is not? and would that also make it act as if the o2 sensor was bad?
One way I check the output of the coil, is to take a known GOOD plug, and ground it against the frame. Do you have a yellow spark or a blue spark? Yellow is weak, Blue is strong.
You can also disconnect the coil wire from the dizzy, use a long screwdriver or one that will fit in the end of the coil wire and ground it against the frame. Same thing goes for the colors. Even though it's stock from '93, it could still be good. I had a problem with a 2 month old MSD Blaster coil, and when I put the stock coil back on, the truck started immediately. The MSD coil wouldn't fire when cold, but would if I warmed it up with a hairdryer.
If in doubt about the operation or age of the O2 sensor, I would spend the $45-$53 for a new one. Just eliminate that problem all together. If you do a search under my name, you will find a wealth of info in regards to problems with either a RICH or LEAN situation.
Also, what plug gap are you running? If the stock coil is weak and you are running .56-.60, you could very well be runing rich. What plugs did you install or the mechanic install? Regular Motorcraft coppers' or Autolites? Anything other than those 2 will also give you problems, i.e., Platinums, Splitfires..
Sorry for the long delay, had to take care of a family situation. well i tested the plugs and they were good, and the o2 sensor is good but i still have a flood situation. i even tried to use a three stage fuel cleaner on it and it did not work. and the plugs are motorcraft coppers. the mechanic put them in for me at .044 calibration. what else could it be?
yeah they all look the same except cylinder #3 is eating oil some. i have listened to all the injectors and they are all working correctly, i have tested the coolant temp sensor and it was within design specs, and no rat nest in the airbox since it is cold air intake and has no airbox. lol