Posted: 3/21/2025 6:18:47 PM EDT
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I have a 2006 Mercury 50 hp four stroke fuel injected outboard on my boat. when my motor is idling, I get 12.3 V to 12.5 V. I replaced the stator with a brand new mercury OEM part and I still get the same voltage. Does that mean my regulator/rectifier needs to be replaced? it seems like it’s not charging because when I take it off the trickle charger in the morning and launch the boat, it cranks fine. When I get to my first fishing spot, shut the engine off, fish for a while. When I go to crank the engine, it just clicks. i know its not my trolling motor running it down because the trolling motor is on a separate deep cycle battery and they are not connected in any way that i can tell. any advice is appreciated. thanks |
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Sounds like the regulator/rectifier is bad. It's the little silver box mounted to the port side of the block and has a pair of yellow wires, a red wire, a black wire and a grey wire coming from it. I have never seen a stator go bad on one of those motors. < -- Maintains a fleet of those motors. |
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Welcome to the wonderful world of trying to diagnose an electrical problem on a Mercury outboard.  Before you start buying parts, check both ends of the battery cables. I've had two 90HP where the problem was corrosion inside the + cable sheath. Essentially there wasn't enough copper left to conduct electricity. |
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Originally Posted By John-in-austin: Welcome to the wonderful world of trying to diagnose an electrical problem on a Mercury outboard. Before you start buying parts, check both ends of the battery cables. I've had two 90HP where the problem was corrosion inside the + cable sheath. Essentially there wasn't enough copper left to conduct electricity. Meh. They are easy as most outboards are. You should have 15-18 volts AC coming from the two yellow wires from the stator to the reg/rec and 13.5ish DC from the red wire coming out of the reg/rec when the engine is running at 1000 RPM's or so. Does your tachometer work? |
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Originally Posted By TexasWildcat: only gauge boat has is fuel gauge. i thought about getting the mercury vesselview but have not yet. boat is a 2006 triton 1756 side console The grey wire coming out of the reg/rec is the tachometer signal. That's why I asked about the tach. If the reg/rec is bad, the tach won't work. ETA - How do the bullet connectors on the two yellow wires look? Brown or burnt? |
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just to throw parts at it, i ordered a $50 amazon reg/rec and put it on today. at idle im now getting 12.7v at battery. i reved it to half throttle and was still getting 12.7v. ill fish it for a while and see what happens. can i get a tach at the autoparts and plug it in to the grey wire? will that give me true rpm’s? |
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No. An automotive tach will not work on an outboard. Outboard tachs read the pulses off the stator and need a special tach to work properly. Marine tachs have a switch on the back to set it for how many "poles" are on the stator. Mercs usually are a 12 pole stator, so you set the switch to 12P and it will read correctly. 12.7V seems a bit low. Was the battery fully charged when you tested it? |
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