Twostrokefan
Cadet
- Joined
- Sep 28, 2011
- Messages
- 10
I'd be very grateful for any insights here. 2003 Mercury 90 3cylinder 2stroke used on a reserve SAR boat so hasn't had as much care and attention as the primary boats and I'm trying to get teh Tacho and T+T guages working.
Tacho is immobile with the engine running. Wiring to it seems OK with grey send wire, pos and neg all correct. . Metering with ignition on shows + and - 12v on correct terminals and the send wire 10V positive?
The Trim guage also appears wired correctly and kicks almost fully to down when the ignition is on. It doesn't move at all with engine trimming. When I disconnect the sender and Ohm it the reading is 200Ohms regardless of position so I reckon although I on't have spec readings it's dead and reading the forum suggests it's a mercury weak point.
Instrument lighting in both cases works fine but runs off the nav lights circuit rather than the engine wiring.The SAR guys can't recall the guages working but mentioned the fuse under the cowling for the Trim and Tilt circuit -(Rubber covered blade 20A at the top rear starboard side of the head) just blows a couple of times a year. The supplying dealer never managed to stop that but I just mention it for completeness in case there might be a link.
Any meter readings/suggestions you could provide to help me diagnose the components or suspect connections would be greatly appreciated
Tacho is immobile with the engine running. Wiring to it seems OK with grey send wire, pos and neg all correct. . Metering with ignition on shows + and - 12v on correct terminals and the send wire 10V positive?
The Trim guage also appears wired correctly and kicks almost fully to down when the ignition is on. It doesn't move at all with engine trimming. When I disconnect the sender and Ohm it the reading is 200Ohms regardless of position so I reckon although I on't have spec readings it's dead and reading the forum suggests it's a mercury weak point.
Instrument lighting in both cases works fine but runs off the nav lights circuit rather than the engine wiring.The SAR guys can't recall the guages working but mentioned the fuse under the cowling for the Trim and Tilt circuit -(Rubber covered blade 20A at the top rear starboard side of the head) just blows a couple of times a year. The supplying dealer never managed to stop that but I just mention it for completeness in case there might be a link.
Any meter readings/suggestions you could provide to help me diagnose the components or suspect connections would be greatly appreciated