1985 Mercury won't turn over(start)

[herbee111]

I have 1985 Mercury 90hp outboard. When I turn the key to start it all it does is hum. It will not turn over to start. I checked the battery, key cord, and made sure the handle was in neutral. I dont know if its the starter or selinoid. I can't afford 200.00 dollars for mechanic to look at it.

[rickdb1boat]

Jump from the terminal on the selonoid that goes to the battery to the terminal on the selonoid that goes to the starter(Big Terminals). Should crank if battery and starter is good. Be aware, it will spark when you hook it up. If it goes, selonoid is bad. If not, check the battery for a full charge or substitute a known good battery. Also, check the connections at all points from the battery through the selonoid and to the starter.

[herbee111]

I jumped it from the battery to the selinoid and it did the same thing. What I noticed is that the sprocket on the starter would not go up far enough to contact the fly wheel. Sometimes the sprocket would hit the fly wheel. Does this mean the starter is bad.

[rickdb1boat]

Try shooting a little WD-40 on the shaft where the gear slides. This usually takes care of it, if it's sticking and spinning below the flywheel. Make sure the battery is fully charged, too. Let us know what happens.

[DJ]

Old Merc,Rick is correct. Squirt some WD-40 on the shaft of the starter while working the gear up and down by hand. You'll notice that it will want to ascend and descend the shaft as you rotate it back and forth. Keep spraying and rotating.Also, as mentioned, take apart and clean every battery to engine connection you can find.

[herbee111]

I tried the WD-40 and that worked to get the sprocket up. Now when I try to start it the motor it is straining to turn over like the battery is dead. I charged the battery and it is still struggling to turn over. I even tried my trolling motor battery. Is it the starter?thanks for the help

[rickdb1boat]

Try it Once again, jump it out with a known fully charged battery. Now that it is turning the motor over, this will tell if it's the starter, weak selonoid or connections. Also, before you do this, remove the spark plugs and see if the motor will turn over easily by hand with the flywheel. Let us know..

[herbee111]

I tried to charge my batteries again and I think my charger is dead. I jumped the starter with my booster cables and truck battery. It had hard a time turning over, so I tried to start it with the rope.It was hard to pull with the rope, so I took the spark plugs out and everything worked fine. The starter turned the motor over good without the spark plugs. Now can it be that I'm not mixing my oil to gas ratio properly? I forgot to asked the guy when I purchased the boat, so I have been mixing it 3oz to 1 gallon. The spark plugs look a little dry but not sure.

[herbee111]

BUMP

[seamarc]

Using WD-40 to loosen the bendix is a good idea, just make sure to clean it off with some degreaser and apply some 3 in 1 or the like. WD-40 will dry to a sticky goo, attract more grime and the very problem you fixed with a quick spray will re-occur because of the quick fix.Also, try checking all the starter and motor grounds for corrosion, I like to clean them up with a stainless steel brush, they have a little more "bite" than a brass or plain steel brush.