Mercruiser Wiring Diagram

[Darol Wester]

We have a 1978 Cruiser that has the 260 (350 Chevy) with the serial # 5079900. Where could I get the wiring diagram for this motor/boat?

Also, when the ignition is on and the points are closed, there's a heavy red wire from the battery to the solenoid behind the motor that has a doubled up white wire wrapped together...the white wire heats up. In the book it's called a resister wire. What's it's purpose and should it heat up like that? We're having problems with inconsistent spark at the points and while we're testing, it heats up. Good or bad?

My computer is messin with me tonight. If someone could get rid of my duplicate thread I'd appreciate it. Thanks.

 

[Robj]

Re: Mercruiser Wiring Diagram

That wire is a resistance wire that knocks down the battery voltage to around 9.5 to 10 volts for your points. If you were to run a full 12 volts it will fry your points in no time. Points are a pain, you should consider changing the points to electronic ignition, google Pertronix.

If you are having spark issues, maybe it is time to change the points, condensor, rotor, cap and wires, basically a tune-up. Then try again and see if it resolves your problem.

Good luck and have a great day

Rob.

 

[Darol Wester]

Re: Mercruiser Wiring Diagram

We just replaced everything you mentioned. The works. Should the resistance wire heat up like that? It doesn't get really hot but it gets fairly warm. As far as the points go, we're getting intermitten spark when you manually open them. Motor won't run.

 

[Don S]

Re: Mercruiser Wiring Diagram

It's a resistor, of course it gets warm. That is how they work.

Did you set your dwell for your points? Is the shaft bushings worn out in the distributor?

 

[Darol Wester]

Re: Mercruiser Wiring Diagram

Now I know, that's why I'm here. Points were set. The bushing I'll have to check. Thanks

Any tips on a wiring diagram for this critter?

 

[Don S]

Re: Mercruiser Wiring Diagram

OEM Service manual would be your best bet. Your boat may be a 78, but what about the engine. Not uncommon to have an older model engine installed in a boat. Do you have an engine SN?

 

[Robj]

Re: Mercruiser Wiring Diagram

Next thing to consider is the coil. Maybe change it also, expecially if it is old. They are not that expensive.

Good luck

Rob.