DOA wiring, big boat....

[poppasmurff]

I have a 1981 Century Cortez grande W/dual inboard 5.7L, 3 fuel tanks and complete guage packages for each engine. Nothing works on the dash except some of the dash lights and the two ignition switches. Almost eveything is wired and one engine runs but I have absloutly no guage readings. I am prepping to start a major refit on her this winter but is in the water now to trouble shoot all issues including engines and velvet drive transmissions. Is there some where I can go for the wiring diagrm for this monster?

 

[Silvertip]

Re: DOA wiring, big boat....

The very first step in this process is to determine what type of "Boat" and "Engine" wiring scheme is used. Yes -- there are two electrical systems in a boat. The "boat" system feeds electrical power from the battery(ies) to the console/cabin where it is distributed to the various 12 volt circuits in the boat. The "engne" harness has the circuits related to the engine and usually run to the helm. All of the sender signals (oil pressure, water temp, tach, etc) are in that harness as well as the ignition and starting circuits. Gauges are typically wired in the fashion shown in the sticky titled "Generic Boat Wiring Diagram" at the very top of this forum. In your case, the gauges would be x2 with the feeds for the tach, water temp, oil pressure, and any other engine-specific gauge duplicated. Gauges are typically fed power from the ignition switch so engine-specific gauges would be wired to the ignition switch for that specific engine. There is likely a fuel level selector switch and a single gauge for fuel level or there may be three separate gauges without the switch. Fuel and speedometer for example are not engine-specific gauges so don't look in the engine control harnesses for that wiring.

 

[poppasmurff]

Re: DOA wiring, big boat....

The very first step in this process is to determine what type of "Boat" and "Engine" wiring scheme is used.

Ok so I have to figure out what engine wiring scheme? Forgive a "noob" but how do I do that?

 

[Silvertip]

Re: DOA wiring, big boat....

No -- you start at the batteries. You will find very large battery cables that lead to the engine. Those cables are large because they need to carry the high current for starting. They also flow current back to battery for charging from the generator/alternator. At the battery(ies) for one, or possibly both engines, you will find smaller gauge wire (red & black) that lead forward to wherever the fuse or circuit breaker panel(s) are located. That is the BOAT harness. All accessories will be run from that harness. I'm not implying you need to determine what the engine wiring diagram looks like at this point. There are diagrams for that in the service manuals specific to your engine and outdrive. You merely need to find the harness that runs from the engine forward to the helm. It is that harness that you will concentrate on for starting, tachometer, oil pressure, and water temperature as well as tilt & trim issues. You should have at least two batteries, one for each engine. And on this boat you would likely have at least one or two large deep cycle batteries for house power (12 volts for all lighting and accessories).