Ford Repair: fuel system 1987 mustang convertable 2.3l, inertia switch, fuel pump relay

Question
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Followup To
Question -
I have gone through 3 fuel pumps in a year.  When the car failed again I removed the fuel pump and jumped it to the battery and it works this time.  I checked for voltage first at the fuel pump, then the fuel pump relay, and the at the fuel pump inertia switch.  No voltage anywhere.  My wiring diagram shows the voltage coming from the "engine electronis control processor" pin number 57.  Could this be bad and if so where is it located?  Should you be able to read a constant 28VDC with the ignition on?
Answer -
Mr. Cast,

I would check your inertia switch first to see if it is bad as you should have had voltage to the inertia switch first. Your electronic control processor should be located behide the glovebox or passenger side under the dash. There is no way to check and see if that processor is bad without placing your vehicle on a scan tool to pin poin the trouble. Auto Zone or Advanced Auto does this test for free, just make sure that they know what they are doing. You will not necessarily beable to read a constant 28VDC with your ignition on as it all depends on what computer is in your car. Hope that this hleps and if you need further assistance, please do not hesitate to contact me. Good luck.


Ken

I found two problems.  One was a corroded connecter under the dash.  I fixed that and then had power all the way to the fuel pump relay but no power out.  I jumper around the relay and everything worked fine.  My only question is what does the relay do?  I have ordered a new relay but in the meantime will it hurt the car to run it with the fuel pump getting constant power when the car ignition is on?

Answer
Mr. Cast,

First let me address the running of your fuel pump in the manner of whihc you have described. You CAN NOT run your fuel pump on direct, constant power. It is a fire hazard and COULD KILL YOU.....it is a MAJOR safety hazard and I STRONGLY recommend that you DO NOT run your fuel pump that way.


The relay shuts your fuel pump on and off as needed. It is a safety mechanism to prevent fires, which I have addressed above. Hope that this helps and if you need further assistance, do not hesitate to contact me. Good luck.


Ken