Fuel pump doesn't turn off

Asked by May 04, 2018 at 11:07 AM about the 1994 Mercury Sable

Question type: General

On my Mercury when I turn the key the fuel pump
comes on usually stays on for a minute then the
car starts now the fuel pump just stays on and on
doesn't turn off and won't start

1 Answer

4,530

Does this happens with the key in the ignition? Anytime the fuel pump stays running with the key on it's usually a stuck fuel pump relay or most likely a bad engine computer (PCM). If not, do the accessories work, radio, horn? If they work, check the ignition switch to see if it's shorting out and remaining ON, if it is OK, next check the fuel pump relay making sure that it is not stuck closed (there is only continuity across one set of contacts on the relay; if you have continuity across both, then its stuck closed). If your relay turns out to be good, see if the relay's power circuit is energized with the key turned off. If so, the problem can be a short in the relay control circuit, or a bad ECU. If the relay's circuit is not energized, then you're just going to have to start following the wire back from the pump to the relay, checking every so often to find out where power is having a short into the circuit. I copied these procedures from my Ford Shop Service Manual, revised October 1996. I hope the information is somehow helpful to you.

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