Decided to ditch the alternator at least temporarily as I have so much solar and only ever run the motor for short periods.

Had a bunch of other jobs to do on the boat and pulled the alternator towards the end of my time; put electrical tape around the six wires I pulled off, bundled them together and taped them out of the way.

Perhaps optimistically I then tried to start the motor with absolutely no result from turning the ignition key.

I had assumed that the tacho probably wouldn't work but nothing on the starter panel seems to work including the low oil pressure warning.

Six wires going to the alternator seems to be excessive and I was wondering if anybody could point me in the right direction as to what they all do and which ones I might need to join together to get the motor to run without the alternator. I did try the motor a little while ago without the belt and it works fine without the alternator actually spinning.

I will be going down tomorrow to try and trace some of the wires but access is terrible and I highly suspect that the colours of the wires that emerge at the back of the terribly inaccessible starter panel will bear no relationship to the color of the wires at the alternator due to the efforts of multiple previous owners.

First step will be to join the two green wires together and also to join the white wire to the thick orange cable as at least doing this can't short anything out but this may well not be sufficient.

One thing that worries me a bit is getting the thing going and then somehow inadvertently having disabled the stop solenoid.

The couple of pictures are below and any comments would be appreciated.

Put the wires back where they were. Put a switch in the fields wire and have it turned off if you don't want to use the alternator. If you want to start the motor after dark turn the switch on. That way the battery gets back to full quickly. Check the temperature of the alternator with your hand while the engine is off and there is power to the starter motor. If the alternator gets warm you have stuffed up the wiring. I don't run my alternator. It's just there to tension the belt. No hp loss to the alternator.

First I have to ask why ? If the battery is sufficiently charged via the solar pv, then the alternator will be causing little drag on the engine and while it's in situ you have a back up charging system ? Anyway if I had to bypass such a system I would assume that each of the poles on the alt act as a bus bar so try connecting together what is connected at the alternator. Obviously the taco won't work and imho running the redundant alt simply for the taco is worth while

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woko said..
First I have to ask why ? If the battery is sufficiently charged via the solar pv, then the alternator will be causing little drag on the engine and while it's in situ you have a back up charging system ? Anyway if I had to bypass such a system I would assume that each of the poles on the alt act as a bus bar so try connecting together what is connected at the alternator. Obviously the taco won't work and imho running the redundant alt simply for the taco is worth while

The alternator will take up to 5 hp from the engine for a few minutes. Depends on the amps. With a 20 hp motor you notice that!

I'm not even sure whether mine works or not but in any event the belt that drives it doesn't drive the water pump or anything else and as it's very tight in there the alternator blocks access to a lot of other things on the motor so is generally a pain in the neck when you want to access something else as it requires temporary removal and reinstallation anyway.

As Ramona suggested put the wiring back how it was and check motor still will start, just to make sure nothing inadvertently broke causing a red herring.

Then take off only one wire connection to alternator and check if that removal causes the engine not to start. Then the next one and then the next one. If you find one that stops the engine starting investigate that one.

Where there is more than one wire on an alternator terminal the wiring system might be using the alternator terminals as through connections. Connect the wires that go onto that particular point together (use a nut and bolt maybe) but remove them from the alternator terminal. Check if that causes the engine not to start.

With no wiring drawing of the boat and electrics step by step should figure it out. I will give you a call later.

BTW I took the alternator off my engine a year ago. It added space, got rid of the whining sound, more engine power and I didnt need to buy a new one at the time.

Thanks for the help guys. Running sweet now with oil pressure alarm working although no tacho which was acting up anyway. I know what the motor is supposed to sound like at full throttle anyway.

It was simply a matter of joining the thick orange and thin red wires which were both on the positive terminal anyway and also joining the two green wires which were joined anyway because they were both on the opposing terminal.

Easier to access everything on the side of the engine now without dismantling anything and I'll take the alternator home for a bit of a cleanup and storage should I ever needed again or sell the boat.