Do you believe the PCM and fuel pump were both bad?

Your situation was one of the most involved I've seen in a long time. I so glad you have it behind you.

Yes, I actually believe it because of the involvement of my husband's coworker before going to the dealership and the afterward when he got the car back and confirmed the fuel pump problem. I am glad it is behind us at this point as well. Thanks again for you help throughout the process.

Almost the same problem as you have that the Engine Check light is lit up the day before yesterday 6/25/10 Friday, and within 2 days till today 6/27/10 I fixed it.
I am a school bus driver. 6/25/10 I was back home late because my summer campus route practice from midtown to downtown Manhattan. My car 2003 mercury sable premium LS parked in the sun from 12:00pm to 6:30pm. I drove home by 6:55pm and got my car fueled at a gas station near by my home. I tightened the gas cap. However, when I drove back into my gauge, I backed too much almost hit the back wall, so I immediately shifted to forward. I never did this before that shifted the back and forward too fast and too hard, then gave me a shock, the ENGINE CHECK light lit up and won't go away. But my car mileage is only 39,119! How could it be? I came to this website and read some info as "Get in the car, fasten your seat belt, lower the driver's window, and turn the ignition switch to ON. You should hear the fuel pump run (humm) for two seconds."

My car 2003 mercury sable LS 39,119 miles, backed off too hard and then too fast shifted forward to park into my gauge, then ENGINE CHECK light lit up. I got in the car, fasten your seat belt, lower the driver's window, and turn the ignition switch to ON. I heard the fuel pump run (very light "humm") for one second, (but the sound is very very light, if my ear is not sharp I could not even hear it), and then I heard a big sound (Humm!! )under the hood which is the front fan pump. This is enough for me to know my fuel pump is good. Now I came to figure it out why the Engine Check is lit up. I went to Radioshak and got a multimeter with two testing pens, one red, one black which is 26 dollars plus tax total 29 dollars. Why? Because the lighting tester won't work in the right way! I took off all the fuses from the black colored Fuses Compartment box under the hood close to the battery by opening the cover of the box. I carefully put them down one by one and wrote down their numbers in order, I did not see #16 but only #10, #15, #20, #30, #40, #50, it's funny, when put #20 up set down, it became into #02, but I just followed the way two of the #20 had been as they were up set down as #02. I cleaned the fuses, then I used my multimeter red pen as positive touched one end of a fuse and used the black pen as negative to touch the other end of this fuse, while the multimeter control arrow pointed to" R x 1" of OHMS range, then the indicator pointed to 10 of OHMS, which meant that this fuse is in good of resistance condition and was not blown up. I tested all the fuses one by one, and then I put them back to the box one by one in order accurately. None of the fuses is in problem that is the answer from the test. When I was testing the fuses, a neighbor of mine walked by and gave me a "Humm!" meaning my car is in a problem, but I don't care what she laughed at, I just focused on my job. I covered back up the cover of the Fuses Compartment box and then close the hood. I redo again , got in the car, fasten my seat belt, lower the driver's window, and turn the ignition switch to ON. I heard in the back the fuel pump run (very light "humm") for one second, and then a very loud sound "humm!!!" from the front under the hood which is the front Fan pump. I did twice of this, I saw the ENGING CHECK light be there the same, still won't go away. Then I turn the key to start the car engine after ON. When the engine is on, I saw the ENGING CHECK light just stayed for 3 seconds, and then gone. I fixed it!

The reason of my car ENGING CHECK light lit up is because the lean level of the fuel in my car tank when I backed up very fast and then I forward up very fast which made the level of the fuel in lean which caused the oxygen senser give car computer a signal that the fuel supply system is short of fuel to support the engine , meaning misfire in the engine. Therefore, this problem is faulse problem, can be fixed by move away all the fuses from the fuse box and then put them back up as they were. In addition, today I replaced the fuel filter too. My car changed the fuel filter when it was in 15000 miles, by30,000 miles I was supposed to do it again but I didn't. Today is 39,119 miles which is 9119 miles over the schedule.

I had the same problem on my 2000 Sable. Have been able to pull the hose off the filter and move the switch to start for a few moments to clean the line and put it back. That didn't work today so I found this page and reseated the relays and it started right up. That wasn't the first of your suggestions that I tried, but that fixed it. Thanks for the list of things to check. You saved the day.

Guest42, is this the suggestion that worked, "Remove Relay No. 29, clean the contacts, and reinstall?"

I go an extra step and apply a light coat of dielectric grease to the cleaned relay and fuse contacts; i.e. military preparedness.

It was dark so I reseated all of the relays. I am going to have to clean the contacts though, or possibly replace 29, because I had the same problem twice yesterday while out of town. I learned a lot from the military too, but probably will not take the extra step unless it is necessary (I'm doing good to keep my oil changed.)