2200 SC no power

[ynot]

The problem I am currently facing that there is no power to parts of the dash and the ignition.
There is power to the bilge, lights, blower ect but the nothing on the gauges and absolutely no ignition.
The trim works.
It has been an intermittent problem that has surfaced 5 times. Four times in the front yard and once on the water.
Originally I cleaned all the terminals on the starter motor and that seemed to work. When it did it again I was playing with the trim and that seemed to work.
I have now pulled the throttle control off to have a look at that, and even though I found some broken plastic in it, which explained why I could put into gear without pulling the red button it, I can't see how it affects the ignition.
The stereo seems to be on a circuit all of it's own, when I gave the starter motor a little tap the stereo lit up.
Confused.
Any help will be appreciated.

[mmwjr]

If you know how to use a voltmeter it’s too me to start checking to isolate where the power is lost. On top of the engine is a circuit breaker with a red button. Measure to see if voltage exists on both terminals. Next measure for power on the B terminal on the back of the ignition switch. Note the issue could also be a bad negative connection. Get the Mercruiser wiring diagram to help troubleshoot.

[jrsick]

Download the manual for your engine from the documents section. There is excellent discussion on testing gauges. Your problem is not likely to actually be the gauges, but testing them will give some good info.
Most electrical issues are basic, and often result of a bad ground or bad battery.
I think your grounding stud will be on the back of the engine. Follow the grounding wire for the distributor coil. Clean the connectors and make sure there is no corrosion on the stud.
What is your static battery voltage? Should be 12.6 to 12.8. Also test for voltage at the battery positive terminal and the engine grounding point. Should be the same readings.

[ynot]

Awesome advise, thanks everyone. I will get the volt meter out and start looking around.

[ynot]

I printed up the wiring diagram and attacked the boat with new enthusiasm. I checked the battery and earth connections. 12.8 volts and everything looked fine. Worked my way to the starter motor and everything tested fine, 12.8 volts and everything tight and clean.
I found the red button engine protector, and I thought I had found my problem. No voltage at the back of it. I pulled it off and the leads tested 12.8 volts. I joined the leads together and still nothing at the dash or the ignition.
I tool the engine protector to my local MerCrusier dealer and he told me there was no way it could be that. He sold me a fuse that goes on the positive terminal of the starter motor. I couldn't find where that goes.
Looking at the diagram I noticed a plug. I pulled it apart and the engine side has 12.8 volts.
My conclusion is I have a problem with the loom or a loose connection where the loom disappears into the dash, or there's another fuse not on the diagram.
Any assistance would be appreciated..

[mmwjr]

Did you check for power on the B terminal of the ignition switch? If no power the issue could be the 20 amp fuse or the 10 pin connector. Both are know issues on older boats. Note when checking power for the start circuit it needs to be checked when the key is in the start position since this is a high current draw situation that can result in a large voltage drop if there is a loose or corroded connection.

[ynot]

Fixed: Thanks every one for your input. After being convinced the problem was aft, it turned out the be the B terminal on the ignition switch. Bad connections.
At least now I have a much better understanding of the wiring system and everything is clean and tight.
Till next time !

[mmwjr]

Cool, glad you figured it out.