fuel pump runs all the time
 

OK i am new here, and after having a head gasket on 92 ranger at 142,000 the garage put used engine in, and so far replaced almost everything under the hood. last problem was crank sensor and balancer (bent)( it would not start when warm), got that fixed.(he had to remove timing cover) Now..... the fuel pump runs all the time with the key on and the engine off.
Any advice appreciated

Welcome to the forum

Ford used same setup for electric fuel pumps for many years.

There is a fuel pump fuse in the engine fuse box, 30amp usually, FP Fuse, it has power 24/7, all the time

The FP fuse is connected to the Fuel Pump relay and when Relay is closed, it connects to Fuel pump, and it runs

The Fuel Pump relay's coil(activates relay) gets power when key is turned on, but has no Ground, so stays open, no power to pump
Computer Grounds the fuel pump relay to activate it

Computer normally grounds FP Relay for 2 seconds EACH TIME key is turned ON, that's to Prime the fuel system.
Then computer won't Ground FP Relay again until RPMs are above 400, engine started.

So if fuel pump is off with key OFF, and on longer than 2 seconds with key ON, that would tell me the Ground Control wire between FP Relay and Computer is bare metal and touching body/engine metal, Grounding out, or Computer itself is doing it.
It wouldn't be a bad relay or fuel pump would run all the time, key ON/OFF wouldn't matter

There is an FP Relay test point, on the OBD Connector in the engine bay
Drawing of it here: Ford Ranger - Testing EEC-IV Equipped Engines

The slot labelled Fuel Pump is the GROUND for the FP relay
So the wire on that slot is spliced to the FP Relay to computer(pin 22) wire
It is there so you can manually Ground the FP Relay if testing Fuel Pump or other issue.

But you could also check it to see if it is a Ground all the time, it shouldn't be, and check wire on that slot, if it had bare spot same grounding effect could happen


Many use that OBD connector Fuel Pump slot and run it Grounded all the time, doesn't hurt if fuel pump is running before engine starts, and it is on full time when engine is running, and then off with key off.
Better to have it working as it should, always, but unless you leave the key in the RUN(on) position for long periods with engine off, it won't hurt anything.