Something is Killing the Fuel Pump Relay

[DryDog]

Jan 04 the FPR in my 91 X died in the locked in mode. The only way to kill the FP when I shut off the key was to pull the FPR. I replaced it and no worries. Until Aug when it went bad again. This time the FP would continue to run for about a second after key off, and if I did not drive it for 24 hrs the battery would be dead. I replaced the FPR and was good until Nov when the same thing occured. About a month ago I replaced the fuel pump AND the relay. I came out yesterday morning to a dead battery. It is happening again!

FPR has gone from $15 to $30. Battery is 2 yrs old. Any thoughts??

 

[MrShorty]

Are you sure it's the relay itself? A short to ground in the wire from the relay to the computer could do the same thing.

 

[unclemeat]

Have you changed the other relay? I had a problem with my FPR and according to my research the ECU relay beside the FPR also has some control over the fuel pump relay. I have not change mine yet, but I intend to. Also did you us a motorcraft (made in the USA) relay? I had a problem using an Advance Auto (made in India) relay.

 

[DryDog]

Pretty sure, It seems to go back to normal when I install a new relay. And is usually OK for several months. This time it's been weeks.

 

[DryDog]

Sorry, too quick on the post

All relays have come from Ford.

 

[DeRocha]

This doesn't address why your relay is getting stuck, but I have installed a fuel pump light (green LED) and manual override switch in my '93 xlt. The light only comes on when the fuel pump is getting 12v. I can use the toggle switch to manual disable the fuel pump (for changing the fuel filter and acting as a poor mans theft deterrent).

 

[DryDog]

In case someone does a search for "EEC Relay" like I did, I wanted to followup with the resolution.
When I replaced the EEC Relay. It solved the battery draining problem but also I had noticed in the past couple weeks the engine would want to die about 2 sec after starting, if it had been off for 6+ hours. Repacing the EEC relay fixed this too.

I hated to have to give up the original one. The FP replay I replaced a month ago I found had separated. The harness with relay plugged in was laying under my KKM filter, while the plastic top was still secured in the relay holder. Ford must have made it on a Friday afternoon.

 

[JimT]

When you replace the relays, make sure that you put them back on the mounts. The "vertical mounting" appears to use gravity to help the relays turn off. I have a '91 Explorer which had the same problems. I found that the relays where all laying on the fender well. By just mounting them correctly the problem ceased. I didn't even need to replace them.

Jim T in Baltimore