543 Error code on 94 4.0 Ranger
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Joined: Feb 2002
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543 Error code on 94 4.0 Ranger
This was a key on engine off test. I got the error code 543 which says - Fuel pump monitor circuit shows no power. Is it time to replace the fuel pump? The truck runs good for a while but when driving down the road at no specific time it just dies and will not restart. I pull over and turn the key off and on and can hear the fuel pump activate but the engine still won't start until I turn the key on and off several times to push more fuel up. But then it runs for a good while. It's only died on me three times like that in the past two weeks.
Post Fiend
Joined: Dec 2001
Posts: 10,562
Likes: 4
From: South Jersey
543 Error code on 94 4.0 Ranger
I would check the fuel pressure and have the filter changed before doing the pump, they are not cheap. If you do the pump pull the bed off instead of dropping the tank. ALso the relay can go bad, another cheap part to replace. Just to be sure I believe the 94s still had the TFI module for the ignition, which is a known problem, are you sure it's not a spark problem?
Posting Guru
Joined: Apr 2000
Posts: 1,746
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From: PNW
543 Error code on 94 4.0 Ranger
Add the fuel pump cutoff switch to the list. It can get flaky and cause the fuel pump to quit unexpectedly. Unlike the fuel pump, it's relatively cheap and easy to replace.
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