View Full Version : mercury starter motor bench test advice

24-04-2011, 04:24 PM
Hi all,

I was wondering if someone could give me some advice about doing a bench test on a mercury 90 hp starter motor?

i took mine off to change the drive assembly, and thought whilst i was at it, id pull it apart to check it overall health (its rather old...) So i cleaned it out, checked the magnets, cleaned all the connections, and put it back together with the new drive assembly.

I then tried to put some power to it to test it prior to it going back in the boat, but nothing happened. So i pulled it apart again, made sure everything was the way it should be, but still it wouldnt fire. I have checked it over with a ohmmeter as per the service manual, but still nothing. I have also tried several different batteries and several different leads. Still nothing.

Being a relative novice at outboard repair, i cant work out why its not firing. Any one have any suggestions of what else to try??



25-04-2011, 01:03 PM
1. are you getting good contact with the positive terminal and the mounting bracket of the starter?

2. did you polish the comutator and scrape the groves in the comutator.

3. did the brushes reseat properly when you reassembled

4. iff there is a lug or a loop that connects the body to the chasis side of the brushes, is this in the right place and bolted down tight

5. is everything assembed right way round.....not sure of this one but some the endcap/brush carrier will fit on two ways, one way works.