Re: power trim problem on 1991 3.0ltr 120 hp Force
Bad relay
Swap the 2 relays around, there is one for the "up" circuit, and one for the "down" circuit.
After swapping the relays, try it. If the relay is bad, now the engine should go down, but not up.
If this is the case, buy a new relay.
If this is NOT the case, you have a wiring problem, either a broken or disconnected wire, or a bad switch.