1987 merc 45hp.....need some trim motor advice....

Cultclassics#37 · Apr 29, 2015

iv scoured the internet and this site to find out what my issue may be....no spark, still gotta check stator, and switch box, and trigger but im no master with the ohm meter, and hoped someone may know what wires to test and where to start? this is a good motor, with compression of 132,134,135,137....anyone want to take a stab at where to start? the fish are biting, and my boat sits in my garage like a worthless pos.....any advice would be great! any local help would be amazing! im new here, and looking to get this classic 50 out on the water!
thanks in advance!

JMichael · Apr 30, 2015

Do you have a service manual for that motor? That should help with telling how to test which items as well as telling you what meter reading to expect.

DaleH · Apr 30, 2015

FWIW I have the '97 version of that motor and found the Mercury service manual on-line that I was able to download.

kofkorn · Apr 30, 2015

The CDI Electronics troubleshooting guide is a very good place to start:

https://issuu.com/cdielectronics/docs/practical_ouboard_ignition_troubles

Find your ignition type and read through it. It goes step by step through most electrical issues and gives you detailed info on how to check it. Having the right tools is important though.

Good luck!

Cultclassics#37 · May 6, 2015

switchbox is smoked.....power to the right side, but no power on the left.....cracks in the epoxy running top to bottom in two different spots that i didnt see earlier! oh well, at least i know now....anyone have a lead on a replacement for my mercury switchbox part number 332-5772-c? i find quite a few on ebay but not all of them list it with the -c on the end? will a part 332-5772 work? anyone replace their mercury with a cdi brand?

JMichael · May 6, 2015

I just ordered a new aftermarket switchbox from ebay for a friends motor. It's not the same part # and I'm not sure of the mfg/brand. I just looked for a decent price, a top rated seller that has a return policy and pulled the trigger. I guess time will tell because when I came in from fishing today, the part had arrived.

Cultclassics#37 · May 12, 2015

thanks for the info guys.... i ordered a switchbox and hoping to have it in the next 4 or 5 days.....now on to the next issue, my trim motor is smoked....i removed it last night and a couple of the brushes were seized...is this something i can fix? anyone ever fix one? i hate to spend another $180 unless i have to...any advice would help!

JMichael · May 13, 2015

If you can't replace the brushes yourself, you might be able to get the motor rebuilt at a starter/alternator rebuild shop. I know getting a starter rebuilt is a lot cheaper than buying a new one so that might be another alternative.