Mercury 115HP 2 stroke - won't start - FIXED

convergent

Petty Officer 1st Class
Joined
May 17, 2010
Messages
385
I have the Glasstream boat listed in my signature and it has an in boat charger that I always hook up when I get it home. Yesterday we went out on the boat for a couple of hours and had to pull it out because a storm came out. We waited about an hour and went back in for another couple of hours. We were skiing and tubing so we would run for a while and then each time we switched I would turn it off as usual. It was doing fine the whole time and then it just all of a sudden wouldn't start. I got the "click" like the solenoid engaged, but nothing. Then a few times it would turn over VERY slowly. But never came close to starting again. I haven't had a chance to do any in depth investigation yet, but from the dash gauge it looks like the voltage was down from the 13V that it usually shows, although the trim, radio, etc. all worked fine.

The only thing unusual about the day was that we pulled out for about an hour and I think the radio was left on. But it started fine when we went back in and had gotten cold so it did have to turnover for a few seconds to start.

So I'm wondering what the possible reasons are for this. Do I have a stator problem that caused it to run down, or do I have a faulty battery? Or could a cable problem do this? I do have one of those overall power switches too.

What's the best way to rule out a few things on this? I am hoping its not a stator problem, but not really sure how to determine it.

Thanks for any ideas.
 
Last edited:

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Had to get towed in for the first time

Re: Had to get towed in for the first time

The answer is "yes" to all of your suggestions. The solution is to take a logical troubleshooting approach and not just throw parts at the issue hoping to get lucky. Here are some hints:
1) Measure the battery voltage. Then measure it again while trying to start the engine. If the voltage drops below 10 volts while trying to start the battery is discharged or bad. Charge it and then have it load tested at any auto store -- test is generally free.

2) If the battery checks ok, disconnect the large battery cables and clean the terminal ends and battery terminals thoroughly. That means both the battery end and the engine end. Reinstall the cables and tighten them securely. If you use wing nuts on the battery posts, replace them with stainless hex nuts and a start washer for better connections.

3) If the issue is not resolved at this point, Use jumper cables to jump directly to the starter. Black cable goes from battery NEG to engine block (unpainted bolt or bracket). Red cable goes from battery POS and touched to the large post on the starter solenoid that feeds the starter. If it still doesn't spin, you have a bad starter. If it does spin, then the solenoid is suspect.

The ignition switch, neutral start switch and the start switch wiring can also play into this but I doubt that's the issue. The solenoid can be verified by using a screwdriver to jump the small terminal to the large terminal to which the POS battery cable is connected. If doing that spins the engine, the solenoid is good and the wiring/switches are suspect.
 

Doernuth

Petty Officer 1st Class
Joined
Jul 6, 2010
Messages
332
Re: Had to get towed in for the first time

Re: Had to get towed in for the first time

Also if you can get the engine running check the voltage at the battery terminals while running. The drop in the voltage guage may indicate a charging problem. Should be 13 to 14 v at terminal while running.
 

convergent

Petty Officer 1st Class
Joined
May 17, 2010
Messages
385
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

I just did an initial test of the battery. I didn't charge it last night because I wanted to look at it as it was yesterday. The battery voltage is about 12.6V, which should be OK I think. When I turn the ignition switch, it drops down to about 8V by the dash gauge, and stays there until I release the switch. I guess I'll take it into the store to have it load tested, as that doesn't seem good based on the replies in the thread. If that is it, I will be surprised because of how it just all of a sudden went from working to not working. I was expecting the voltage on the battery to be down to start with, but its not.
 

fuzzybob

Petty Officer 1st Class
Joined
Oct 26, 2008
Messages
213
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

???
 
Last edited:

convergent

Petty Officer 1st Class
Joined
May 17, 2010
Messages
385
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

I am still on Silvertip's Step 1 above. I had time tonight to try swapping my trolling battery with the starting battery. They are both marine starting batteries, so I would think this would work and help in the diagnosis. Well it was inconclusive. The trolling battery behaved exactly the same as the other battery. Started around 12.6V and dropped down to about 8V when I hit the key. Cranking was equally slow. That battery would have been drained down a bit to start because I use the trolling motor a lot before I someone saw us and gave us a tow.

I went ahead and plugged in the onboard charger and will give it a try in the morning to see if it cranks any faster. If it does, then I need to figure out the next move. I am guessing that I'm going to have 2 batteries that will turn it over fast in the morning, which will rule out the stuff in Step 2 and 3. If that is what happens, then it would seem like I have a charging problem. I suppose I can bring both batteries in to the store and have them load testing too.

I need to pick up some muffs tomorrow so I can start it in the driveway and let it run to measure the voltage on the batteries while its running. If the voltage is not up at 13-14V while running on muffs, then does that automatically mean my stator is bad? Are there any switches or anything on bass/fish&ski boats that would change the charging? There is a switch up on the front panel that has a charging setting but I've not touched that switch since I've had the boat and never had the starting problem before. So I'll research stator problems.
 

zebrex

Cadet
Joined
Aug 18, 2009
Messages
18
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

your starter is bad
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

your starter is bad

I second that.

I'd either just replace the starter, or if I felt the need to verify I would use a cheap current tester (hold it against the wire amp meter) to verify high starter current.

The vertically mounted starter with the end type wedge brushes in the bottom as mounted tend to short out from brush debris in a way that looks like a bad battery. I'm supposed to be an expert, and I got fooled by mine so I gave away a perfectly good battery and paid 80 bucks for a lesser one at a marina.

If the mechanical part is in good shape, (bushings, drive) it's pretty easy to replace the brushes and maybe brush holder. You do have to make a tool out of a tin can, but the directions are in the manual.

hope it helps.
John
 

convergent

Petty Officer 1st Class
Joined
May 17, 2010
Messages
385
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

OK, I charged both batteries up fully and they will both turn it over faster than before, but still pretty slow compared to what it did up until we got stranded. Its probably about 1.5-2 seconds per crank. I am cranking it in my garage, and I assume it should crank as fast as in the water, right? Normally it was turning over about 3-4 cranks per second (just making a rough guess).

The motor and boat are both in really excellent condition and the cable "looks" to be like new on both ends. Not sure if it has a problem in between.

It sounds like you guys are thinking its the starter motor gone bad. Is it worth taking the batteries in for a load test? I've never tried to start the boat with the trolling battery, but fully charged they are both cranking slow.

If I were going to replace the brushes, are they something I could buy at a local shop, or am I going to have to order it? If so, I may just get the motor and be done with it more quickly.

I have the OEM manual and am looking at the brush replacement and it looks kind of difficult. Are there other tests I should do to 100% verify its the starter motor that is dead?
 

convergent

Petty Officer 1st Class
Joined
May 17, 2010
Messages
385
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

I went ahead and ordered a starter... otherwise it will be next week sometime before I can potentially get this working. The one in there I think is original, so its not a bad thing to have a new starter anyways. I'll post back if this fixes it.
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

I went ahead and ordered a starter... otherwise it will be next week sometime before I can potentially get this working. The one in there I think is original, so its not a bad thing to have a new starter anyways. I'll post back if this fixes it.

It will.:D
 

convergent

Petty Officer 1st Class
Joined
May 17, 2010
Messages
385
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start


I love the confidence! :)

It kind of makes sense because the boat hadn't been used much before I bought it a couple of months ago. The prior owner bought it from his dad and he said he had only filled it with gas about 3 times in the time he owned it (years). Since then we've been using it a lot, so the big increase in usage may have played havoc with the brushes. I think I've been filling it with gas about twice a week for several months now.
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

I love the confidence! :)

It kind of makes sense because the boat hadn't been used much before I bought it a couple of months ago. The prior owner bought it from his dad and he said he had only filled it with gas about 3 times in the time he owned it (years). Since then we've been using it a lot, so the big increase in usage may have played havoc with the brushes. I think I've been filling it with gas about twice a week for several months now.

They slowly fill up with carbon dust from the brushes, till it shorts out the brushes. Does the word pernicious mean anything to you?

If you want to double check the diagnosis, get one of those little plastic or aluminum amp gauges you hold against the wire and check the starting current. It should be 125 or below. I'll bet it's 250 or above.

hope it helps
john
 

convergent

Petty Officer 1st Class
Joined
May 17, 2010
Messages
385
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

The starter motor will be here tomorrow, so no point doing any further diagnosis until I install that. And given how you've described this, it makes a lot of sense. The voltage drop when trying to start does seem to point to a high current flow.
 

gregtobin

Petty Officer 3rd Class
Joined
Sep 18, 2006
Messages
99
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

I'd suggest that you save your old starter to repair so that you have a spare. I have the same motor and sometimes the throwout gear doesn't throw out. I generally have to remove the starter and do some work on it to lube it up. Helps to have a spare. You can rebuild your spare while you have it laying around.
 

93baylinerjazz

Seaman Apprentice
Joined
Jul 18, 2010
Messages
30
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

Interesting... just bought a jazz on Sunday with a mercury sj. Starter spins too slow to do a compression test even on a charged battery. Does anyone know where I can download a copy of the sj90 manual? I'd love to try to do a rebuild on the starter but have only done automotive starters. Is this fairly similar to replacing the contacts/brushes on an auto starter?

(sorry if this is threadjacking?)
 

milehighboater

Petty Officer 1st Class
Joined
Jul 28, 2009
Messages
235
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

I would still do the load test, it is possible for a battery to maintain the correct voltage without being able to put out enough amps. Might save you from having to do that starter.
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

Interesting... just bought a jazz on Sunday with a mercury sj. Starter spins too slow to do a compression test even on a charged battery. Does anyone know where I can download a copy of the sj90 manual? I'd love to try to do a rebuild on the starter but have only done automotive starters. Is this fairly similar to replacing the contacts/brushes on an auto starter?

(sorry if this is threadjacking?)

If you haven't "tried" it to the point of destroying the armature, about the only other parts in the starter to wear are bushings and brushes. You have to make a tin tool to load the brushes, but it's not difficult. Full instructions are in the manufacturer's manual.

And yes, it's hijacking the thread.
 

convergent

Petty Officer 1st Class
Joined
May 17, 2010
Messages
385
Re: Had to get towed in for the first time - won't start

Re: Had to get towed in for the first time - won't start

I would still do the load test, it is possible for a battery to maintain the correct voltage without being able to put out enough amps. Might save you from having to do that starter.

Since it dropped the voltage on two batteries that were fully charged, I figured it was worth the risk to go with the starter. Also, given the motor is 17 years old and has what looks to be the original starter, and given the comments about the design creating dust in a bad spot, I figured even if it wasn't bad it was good insurance to replace it.

Got the starter today and with the factory manual took only about 15-20 minutes to install, along with reconnecting the batteries and wiring I had ripped apart.

GOOD NEWS! It fixed the problem. This things spins faster than I've ever heard it spin now. I only tried it once because I don't have muffs and don't want it to actually start. I am headed out of town in a couple of hours but will get it in the water Saturday to try it out. I'm pretty confident we are back in business.

That is good advice on trying to repair the old motor to have a spare. I'll do some testing on it and see if its just the brushes when I have time.

Thanks so much for all the great advice... this forum is fantastic. This is my first foray into working on an outboard, but have a lot of experience building engines for my drag car when I was younger (a LONG time ago). I am sold on outboards now. What a breeze to work on! I can only imagine what a pain in the ar$$ it would be to replace a starter on a stern drive with it being under the motor and the motor being down in the hull. Everything on this puppy is right at the perfect level to work on. No busted knuckles either.
 
Top