Charging system on 74 3.0L Merc.

bheff

Petty Officer 3rd Class
Joined
Sep 16, 2009
Messages
75
I bought a 1974 Ranger bass boat with a 3.0L 4 cyl, inboard/outboard. Pretty unique boat. I was finally able to cobble together the wiring and get it running. But Im not sure about the charging system. The wires coming from the battery are a simple red (going to straight to the starter) and a black( grounded on the block). The Alternator has a black wire and a red and white wire. This red/white wire was traced to a large orange wire (amp meter?) that ended under the console. Im also getting readings from the smaller orange wire on the starter and the grounding post to the right of the orange wire.
So how will I know if this set up is actually charging the battery as we run the boat? Can the large orange wire be wired to a VOLT meter to monitor the alternator voltage? (ive bought all new gauges and in the process of making everything right.)
 

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alldodge

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Staff member
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Mar 8, 2009
Messages
42,548
Looks like your alternator has been replaced with a one wire ALT.

alt.jpg


This is how you should be wired. This is an inline 6 but wiring is the same. You can add a voltmeter but connecting the + side to the ignition side and - side to ground.

Old L6 wire eng.jpg

Old L6 wire helm.jpg
 

bheff

Petty Officer 3rd Class
Joined
Sep 16, 2009
Messages
75
Looks like your alternator has been replaced with a one wire ALT.




This is how you should be wired. This is an inline 6 but wiring is the same. You can add a voltmeter but connecting the + side to the ignition side and - side to ground.




Thanks Alldodge, that helps. I hope to finish wiring the console and gauges this weekend.
(2017 Ram1500 Bighorn with Rambo )
 
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