96 Mariner 115 stalls going into gear

[pinellas50]

Re: 96 Mariner 115 stalls going into gear

So I went back at it this morning. I verified no spark on ANY cylinder using my inductive timing light. I then began testing voltage coming to the coils from the switch box. Nothing on cylinders 1 and 2. When I started testing #3 voltage showed up. I then put the timing light back on #3 and it was sparking. At this point I had spark on only 3 and 4. I moved my test leads to check DVA from the trigger and all of a sudden I had spark on all 4 though the spark on #2(the suspect) came and went at first.

At this point I started the motor and it ran. It had a couple of "hick ups" when it first started and I happened to be holding down on the trigger of the timing light with the lead hooked up to #2 when it did this. There was no mistake spark was dropping to cylinder number 2 but then coming back after a few revolutions when these hick ups happened. Then everything started working fine and it idled like a champ. DVA readings on everything I had on the charts looked fine according to my understanding of reading my meter.

So I am back to making educated guesses.

 

[CharlieB]

Re: 96 Mariner 115 stalls going into gear

Guessing is almost as bad as assuming, it can lead to spending a whole LOT of money replacing perfectly good parts before you finally replace the real defective item.

Intermittant spark is often caused by a bad switchbox.

HOWEVER..... that NO RETURN on electrical parts thing, you want to test, twice, to be absolutely certain it is not something else.

Three things can cause strange ignition problems.

First, a defective rectifier/regulator can cause a strange EMF within the stator, a simple test is to disconnect both yellow stator wires that connect to the rect/reg, tape them off and run the motor, if all is well then replace the rect/reg. If not, keep testing.

Second, a broken trigger wire inside the insulation, abuts making contact and works O.K. until the wire is flexed just right then the ends separate and that cyl then fails to spark. Disconnect the throttle cable, remove the spark plugs, ground all the plug wires other than the one testing, while testing/cranking move the throttle/timing lever from idle to WOT and back to move the trigger wires while watching for trigger output to fail.

Third, the ignition is a 'Ground-to-kill' running the black wire with the thin yellow line from the switchbox to the ignition switich, the IG switch in the OFF position grounds the B/Y wire to the solid Black wire, killing all spark. Even a small partial ground can cause the switchbox to kill some spark, it is critical that you unplug the B/Y wire at the switchbox for spark testing. Also test the B/Y wire going to the ignition switch, it should ALWAYS be infinite (No resistance) with the key in the Run position. And NEVER should you have any voltage applied to this wire from the IG switch, that will destroy a switchbox in a hurry.

Verify all the above before condeming the switchbox.

Oh, loose magnets in the flywheel causes strange problems, it would be a good idea to pull the flywheel to inspect the magnets to ensure all are tightly in positions, no wiggling allowed.

 

[James R]

Re: 96 Mariner 115 stalls going into gear

I second CharlieB on the rectifier regulator. Disconnect and run the motor. See what it runs like.

 

[CharlieB]

Re: 96 Mariner 115 stalls going into gear

Reddish brown powder under the flywheel may be rust powder. If you do pull the flywheel to inspect the magnets pay particular attention to the inside of the flywheel AND the outside of the stator coils, looking for any evidence of rubs from the two contacting and rubbing together. The fresh exposed steel will rust and the next time the motor is run then the rust is rubbed off, leaving the red powder.

If this is the case then the upper crank bearing is suspected of being worn loose allowing the crank to wobble.

This can also account for a no spark on one or more cyls as the instant of contact the stator becomes one with the flywheel and NO electricity is generated.

 

[pinellas50]

Re: 96 Mariner 115 stalls going into gear

This is the underside of the flywheel. All magnets are tight and I don't see anyplace where it may have been making contact with the stator.

Stator/trigger assy

Stator close up

Another stator close up

Trigger close up

I don't see anything visually which looks like a problem. The trigger will move up and down a little where it is located but doesn't come out or anything. I can move the timing arm back(retard) and the left side of the trigger pops up some on the left side in this picture at one certain point. I have to disconnect the throttle linkage and see what it does moving towards advance as it would under normal operation.

 

[CharlieB]

Re: 96 Mariner 115 stalls going into gear

Everything looks fine visually, unfortunately that won't tell a thing how well they work.

DVA testing of each component to exclude then is a process of elimination, exclude all the parts working correctly and the only thing left is the switchbox.

I am NOT telling you to replace the switchbox, yet, only that you must carefully test each part, twice, to ensure that it is generating the correct voltage while under the load of the DVA meter or DVA adaptor, OR while the motor is running UNDER LOAD.

You can extend the meter leads clear to the dashboard and watch stator voltage while underway. Repeat for the high side of the stator, the repeat for each trigger lead. If all pass load tests 'then' it is safe to cast suspicion on the switchbox.

I would R&R all coils to ensure ground wires/contact points are clean and making good contact. If you have narrowed down a misfire to a particular cyl swap that coil with another to see if the problem moves witih the coil.

A lot of problem solving is simply time spent checking things, NOT replacing with new parts that can cost a bunch of money.

 

[pinellas50]

Re: 96 Mariner 115 stalls going into gear

I swapped the coils awhile ago and the problem remained on cylinder #2.

OK. So nothing more to do here than put the flywheel back on then. I'll try testing again, find someone who knows what they are doing, or run it till it dies and then have a better chance of figuring out what is wrong I guess.

Am I correct I assuming what I see as say .95 on my meter is 950 when looking for a DVA reading between 700 and 1200? This process really doesn't help when the numbers I see aren't in the same universe as what I am supposed to be seeing.

Thanks all for your help.

 

[quicktach]

Re: 96 Mariner 115 stalls going into gear

Your pix don't show any evident problem. How did the rectifier test go ? I'm suspecting a switchbox. If all other electrical components test ok, and all your grounds are ok, and your wiring is ok, and your plugs are all ok, you end up at the switchbox. Any sign of overheating on the back of the switchbox ? If so - replace it.

 

[pinellas50]

Re: 96 Mariner 115 stalls going into gear

I haven't done any more electrical testing since my last post. Only pulled the flywheel to see if anything looked unusual. I didn't test or disconnect the rectifier but my understanding is it couldn't cause the no spark I had.

I'm still at a loss how I lost everything and then it came back.....in stages.

I'll have to wait till I have another day where I have nothing to do but mess with this thing. Unfortunately those type of days don't come around too often.

I'd love to see an answer about what I am seeing on my meter. I don't have 400 DC as an option on mine as the instructions on my DVA adapter says to use. It goes from 200 and the next selection is 2000 so I have been testing most things with the meter set on 2000.

I am also taking from the responses that doing the resistance tests isn't worth the time compared to DVA tests. Am I correct on that?

 

[pinellas50]

Re: 96 Mariner 115 stalls going into gear

Third, the ignition is a 'Ground-to-kill' running the black wire with the thin yellow line from the switchbox to the ignition switich, the IG switch in the OFF position grounds the B/Y wire to the solid Black wire, killing all spark. Even a small partial ground can cause the switchbox to kill some spark, it is critical that you unplug the B/Y wire at the switchbox for spark testing. Also test the B/Y wire going to the ignition switch, it should ALWAYS be infinite (No resistance) with the key in the Run position. And NEVER should you have any voltage applied to this wire from the IG switch, that will destroy a switchbox in a hurry.

So I found some time to start messing with this again today. I was treated to no spark on any cylinders when I started this morning.

I started from scratch and came to the kill circuit on the switchbox. With the key off everything goes to ground which is correct. However, with the key in the on position I am getting 8 volts on the black/yellow connection at the switchbox.

There are actually 2 wires, both black/yellow going to the kill terminal on the switch box. The wire going to the ignition switch does not have power on it at any time. The second wire is the one which gets voltage with the key on. This wire is in a loom with a brown wire which connects to the terminal for the brown wire coming off the trigger at the switch box. These 2 wires(brown and black/yellow) run down to connectors, the brown wire changes to orange, and a purple wire comes into the mix. From there the black/yellow, orange, and purple wires all run behind some sort of plastic cover on the starboard side of the engine directly under the main connection for the wire harness coming from the control and ignition switch.

When I take black/yellow wires off the switch box spark comes back to all cylinders so the problem with the no spark has to be under that plastic cover. What is under that cover? My wiring diagram suggests it is the Mercury tilt switch but my diagram also only shows that one black/yellow wire going to this switch and not the other two. I don't see any component with all three of these wires going to it.

The second thing is I am going to have to take the lower cowl off to get down into this plastic cover and whatever is under it effectively. How does the lower cowl come off exactly?

I need to get this no spark condition figured out before I can address the high speed miss. I think I have two problems at once here.

 

[carholme]

Re: 96 Mariner 115 stalls going into gear

Pinellas;

What is the s/n of your engine? I am pretty sure that I have the mercury manual for it and can send it to you if you PM me with an email address.

Gerry

 

[pinellas50]

Re: 96 Mariner 115 stalls going into gear

The SN# is OG394903

The motor ran great on the muffs with the black/yellow wire with power on it simply removed and taped up. It seemed like the battery wasn't charging, though it can be hard to tell when the motor is just idling.

Is this offending wire I am talking about somehow hooked up to the wires to the rectifier? That would make sense if my battery isn't charging now and my tach had been dropping out and then coming back a couple of times for no apparent reason.

 

[CharlieB]

Re: 96 Mariner 115 stalls going into gear

............
I started from scratch and came to the kill circuit on the switchbox. With the key off everything goes to ground which is correct. However, with the key in the on position I am getting 8 volts on the black/yellow connection at the switchbox.
.......................

Verify that voltage you found, the ignition switch may have an internal short and most likely will be replaced, immediately if your readings are correct as any voltage thru that ignition switch to the B/Y wire can/will cause permanent damage to the switchbox.

Once that's done and next time out on the water, disconnect the two yellow wires from the stator to the rectifier, run the motor and see if your high speed miss is cured. If so, replace the rectifier.

Sounds like you just about have this motor purring and ready to go out and kill some fish!

 

[pinellas50]

Re: 96 Mariner 115 stalls going into gear

Charlie, what I don't understand with that is the black/yellow coming from the ignition switch, through the main wire harness, does not have any voltage on it. I had this wire hooked up when I was running it earlier and it started and stopped with a turn of the key like it is supposed to do.

It is the other black/yellow wire which also goes to the same terminal on the switchbox. That is the wire with the voltage on it. That is the wire that changes color at a push in connector and disappears under that small plastic cover. I can't figure out on a wiring diagram what these wires are to get an idea of what electrical component might be having the issue. My outside the box thinking says mabey it goes to something on the engine which has the ability to shut the motor down independent of what you do with the key.............like an oil pressure safety switch on a race car or something. Like if that system detected a problem it grounded out the wire going to the switchbox thereby killing the ignition and shutting the motor down. Is there any sort of system like that on this motor? Isn't that pretty much what the mercury tilt switch would do?............though my diagram doesn't show any way that circuit could have a power wire in it.

Are you saying the second wire I am having the voltage on also goes to the ignition switch even though it doesn't seem to go through the harness that goes to the switch. I guess it could with a different wire color.

Do you know what is under that plastic cover I am talking about. If I knew what it was I might be able to get a better bead on what the source of this voltage might be.

 

[carholme]

Re: 96 Mariner 115 stalls going into gear

Your s/n comes up as:

MARINER - (115 H.P. (1996 ))
Serial No: 0G394903 Model No: 7115412ED

Parts List for model 7115412ED:

100/115/125 H.P. 80 JET (4 CYLINDER) - Mercury, Mercruiser, Force, etc. Parts Lookup

The black/yellow coming from the main harness, pin 1 to the switchbox continues from the switchbox to the Rev Limiter and the Limiter gets it voltage through the purple wire coming from the main harness, pin 2.

The rectifier has two yellow wires coming from the stator and continuing on to the voltage regulator. The gray wire from the voltage regulator is also connected through the rectifier, going forward to pin 5 of the main harness.

Gerry

 

[pinellas50]

Re: 96 Mariner 115 stalls going into gear

OK. A rev limiter makes complete sense. That is why I see the other wire going to one of the posts with a trigger wire. It seems like my options here are get a new rev limiter or just disable it. I would prefer to keep it.

So how does that lower cowl or motor cover come out? I see the 2 bolts at the back of the engine which hold that back together. Do you unbolt those and it just comes apart like a clam shell? It seems to be held on much more securely than that.

 

[carholme]

Re: 96 Mariner 115 stalls going into gear

Why don't you make this a lot easier and just let me send you the manual as I offered in post # 31?

Gerry

 

[CharlieB]

Re: 96 Mariner 115 stalls going into gear

The rev limiter should NOT apply voltage to the B/Y, if the module sensed an over rev it should ground the B/Y to momentarily kill spark.

Historically outboards did NOT have r3ev limiters, the prop is the rev limiter.

If the boat 'catches air', then the prop can be UN-loaded and the motor will over rev and can cause damage.

Personally, I would toss the rev limiter and be a bit more careful NOT to WOT on rough water and risk airing the prop.

 

[pinellas50]

Re: 96 Mariner 115 stalls going into gear

carholme, sorry I got caught up in messing with this thing and forgot to get with you about the manual. PM sent and I appreciate the heck out of it!!

Charlie, a lot of me has been thinking the same thing you are saying about this rev limiter. I don't see anyway I could over rev the thing on the water for the reasons you pointed out and I'm not one to go jumping waves. I think I will just diable this thing and be done with it.

Next up is trying to find time to get on the water and see what, if anything, might have changed with my original problems. If they are still there I'll disconnect the rectifier and see what happens.

Thanks for everyone's help!

 

[pinellas50]

Re: 96 Mariner 115 stalls going into gear

Just an update.

I disabled the rev limiter but taking the wire off of the kill circuit on the switchbox, taping up the end, and then wrapping the wire up.

I also put in a new switchbox which cured the stalling going into gear and at low rpm.

Now the only unusual thing is does is run about 5oo rpm higher on the muffs than it does in the water. I'll take that over the stalling. But I am really at a loss as to why it would run at a higher rpm out of the water. The only thing that makes sense is back pressure on the exhaust. But, it has never done this before.