I have 1998 Mercury 250 efi's on the fish boat. Last weekend the trim/tilt on the stb motor just went dead. Neither the switch in the handle or directly on the motor works. No response either direction. Working fine on the other motor.

Any ideas on this? What's a good service manual to use?

Send me an e-mail address, and I will send you a factory manual in PDF format. Check the solenoids on the starboard side of the motor, if neither switch works, probably in there somewhere.

Single or 3-ram trim? If it's a single, you should have a pump in the boat. Look for the green and blue wires (smaller ones) coming from the helm. Should get +12v on the blue when pressing up on the switch, +12v on the green when pressing down (remember blue for sky - UP and green for grass - DOWN).

If you have power there, make sure the power/ground to the solenoids is hot. They should go to the battery or switch, but are fused.

Do you still have this manual? I could sure use it. Thanks, Andy

Check for power back at the trim motor itself, also possible bad trim solenoids mounted on the engine side. I have the manual in book form as I already answered your other post. I have always like the book form manuals better because you can always take it with you on your boat ride plus read it a lot easier in the direct sun light compared to on the computer.

IMO you might have a bad trim motor.