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Tachometer problem with engine swap

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kbrad

New member
A newbie here . I replaced my 1998 50 hp Force outboard with a 2003 90 hp mercury outboard . My tachometer now does not work . Not even a bump . Have not had a chance to check my tach setting being it is a pontoon boat with an enclosed console and little harder to get to . Was thinking I should at least get a blip or bump on the tach even if not set right . Any advice on what wires I might check at the engine just in case ?
 
The gray wire in the wiring harness is the tach signal which comes off the regulator/rectifier. Besides that signal your tach uses 12v, ground, and dash light power. Since you are changing engines, you probably need to dial in a setting on the (back of the) tach corresponding to the alternator pulses. As I recall that engine uses 6....if that is the wrong number someone will catch it and correct me.
 
Texasmark said:
The gray wire in the wiring harness is the tach signal which comes off the regulator/rectifier. Besides that signal your tach uses 12v, ground, and dash light power. Since you are changing engines, you probably need to dial in a setting on the (back of the) tach corresponding to the alternator pulses. As I recall that engine uses 6....if that is the wrong number someone will catch it and correct me.
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Thanks , Texasmark . I did go into the console and tried each of the settings on the tach and still getting nothing . I do want to let you know for sure that the tach was working when I took the 50 hp off . I guess that maybe somewhere on the engine , something is not hooked up ? Thanks again
 
kbrad said:
A newbie here . I replaced my 1998 50 hp Force outboard with a 2003 90 hp mercury outboard . My tachometer now does not work . Not even a bump . Have not had a chance to check my tach setting being it is a pontoon boat with an enclosed console and little harder to get to . Was thinking I should at least get a blip or bump on the tach even if not set right . Any advice on what wires I might check at the engine just in case ?
Click to expand...
Just to update : I did check the tach and tried each setting with no movement on tach at all . It did work with the 50 hp when I took it off the boat . Thanks
 
Sorry for the delay in replying. Your rectifier/regulator module in the engine. may be faulty and not sending out the pulses required for operation. I don't have my service manual handy to give you the values and conditions but somebody may hit this and provide that info.

Other thing you might check is go to that module and follow the wire to the remote wiring harness connections. The grey wire may be outside the 8 pin connector rather than in it so it would be strapped to the side of the cable. Ensure there is a valid connection.
 
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Texasmark said:
Sorry for the delay in replying. Your rectifier/regulator module in the engine. may be faulty and not sending out the pulses required for operation. I don't have my service manual handy to give you the values and conditions but somebody may hit this and provide that info.

Other thing you might check is go to that module and follow the wire to the remote wiring harness connections. The grey wire may be outside the 8 pin connector rather than in it so it would be strapped to the side of the cable. Ensure there is a valid connection.
Click to expand...
Thanks Texasmark , that was the problem . Ordered , received and installed . Now she is charging and tach is working . Thanks again .
 
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