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Mercury 1995 115 runs at WOT, dies below 1200 RPM

Texasmark said:
Trigger circuit, not stator...mounted inside the inside diameter of the stator that charges the battery
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My battery charges when the motor is running. I have 3 LED voltmeters mounted in the rear hatch so I can keep an eye on the batteries. This is a grab from a video while the motor was running, started from cold.

I was thinking that if the stator tests bad, I might replace the trigger also, since the flywheel is off. (I'm pretty sure I know the lever you're talking about.)

My service manual was published December 1996 and covers US serial numbers 0D283222 and above, Belgium 09793577 and above

I had that flasher for many years and never had a problem. What a difference it made when you're looking for the dropoff. It was on a 15' Starcraft with a closed bow. I gave it to my brother who gave it to someone else. In my garage I happened to come across the owner's manual and a plastic red/white adjusting tool. Good times :) All kinds of gadgets now. The replacement for that flasher was a Humminbird TCR-ID1. I was in heaven and caught a lot of fish with it. I still have one (that works) that I bought on eBay; NOS (New, Old Stock). It was still in an unopened box, rusted screws, from someone who got it as a gift and just stuck it in the garage.

vlcsnap-2023-05-03-13h31m09s522.png
 
richw46 said:
My battery charges when the motor is running. I have 3 LED voltmeters mounted in the rear hatch so I can keep an eye on the batteries. This is a grab from a video while the motor was running, started from cold.

I was thinking that if the stator tests bad, I might replace the trigger also, since the flywheel is off. (I'm pretty sure I know the lever you're talking about.)

My service manual was published December 1996 and covers US serial numbers 0D283222 and above, Belgium 09793577 and above

I had that flasher for many years and never had a problem. What a difference it made when you're looking for the dropoff. It was on a 15' Starcraft with a closed bow. I gave it to my brother who gave it to someone else. In my garage I happened to come across the owner's manual and a plastic red/white adjusting tool. Good times :) All kinds of gadgets now. The replacement for that flasher was a Humminbird TCR-ID1. I was in heaven and caught a lot of fish with it. I still have one (that works) that I bought on eBay; NOS (New, Old Stock). It was still in an unopened box, rusted screws, from someone who got it as a gift and just stuck it in the garage.

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I am assuming that you have one connected to the engine and that looks within 0.2 volts of the accepted value of batteries at the top of the charge. Nothing wrong with that Stator! The other 2 I guess, are waiting their turn because if mine are less than 12.75 I put them on a charger and I use a lot of trickle chargers. I have a built in 5 + 5 charger with trickle which keeps them in tip top shape. One thing I found out recently and that is keep them full and they will last. Once I started investigating battery performance in all my equipement...farm, highway, marine, I had no idea that they self discharged as fast as they did. Some of my farm equipment didn't get used for six months and that's way too long to leave them sit. I was amazed at how low the charge was in the battery for a reading of 12.3.

As usual, enjoying the chat.
 
I may have plugged in the onboard charger when this picture was taken but I did check charging status while it was running, before plug in. It was definitely charging. I will check it again on the trip and get another picture. Batteries will discharge with higher humidity, which we have in buckets here. Marine batteries have a 1 year warranty, probably because people let them sit all winter. I know my friends treat theirs that way. I used to keep mine on a trickle charger but that can overcharge and boil out the water. I have a 3-bank Pro Charger, each bank is independent and provides up to 15 amps. It was around $325 in the late 90s and has a lifetime warranty.

The other 2 are batts are for the trolling motor and they are on their last season, particularly if I don't get the motor fixed. Sometimes they charge up to 12.7 but if it's cold, which is was on this day, then they top out at 12.3-12.5. The LED voltmeters are connected to the batteries and are mostly for the trolling motor battery status, fishing or on the onboard charger with shore power. None are connected to the stator. Battery, depending on the temp in the garage, will charge up to 12.7 and hold, when they are new. (SOC by temp chart below is for deep cycle batts.) These need to be replaced for next season. The onboard charger is kind of funny, the way it works. It's a good one, bought in the 90s. When the batteries are low the charger's lights show 4-5 red bars and my gauges show 13.6 to 14.1. As the charge progresses the lights drop one by one and the voltage drops. The charger lights will go 5-green but the voltage is still in the same range and may go up to 14.1 before everything drops to 12.7. The charger is still plugged in but cuts off. If the voltage drops enough it will provide the voltage again. I have never trusted chargers, particularly over winter, so I have the onboard charger on a timer.

My understanding is that the stator provides power to the switch box for the ignition system and also charges the batteries. That's what I see on Boats.net. So one could be bad but the other good??? Are they separate or only 1 pickup? If it's not the stator then I'm back to square one.
Outboard Ignition System Components
Stator
An outboard's ignition system has a stator that generates the power to supply the ignition system, but also supplies power to recharge the boat's batteries.

Learning as I go along. I didn't know anything about trim/tilt but I rebuilt mine 2 years ago and it still works fine. Same goes for the rev limiter and the low oil alarm/bottle. Now I've rebuilt the starter and fuel pump. :cool:
-Rich
State of Charge by Temperature.jpg
 
I must have had a senior moment. I looked closer at the wiring diagrams of yours and mine and realized that my stator provides power to my CDMs low voltage control circuitry too but on different colored wires....green and white. Just hadn't looked at this circuitry for quite awhile.

Therefore I agree that the stator could be your problem after all. Since you are a competent guy in this area, why not bring out 4 wires from the red/red/white, and blue/blue white to access with a voltmeter. Crank the engine cold and measure the outputs. Make the engine fail and immediately crank it while viewing those voltages and see if that's your smoking gun. Sorry for the brain fart!

On the batt. chart, easy to see another reason starting engines in cold weather is taxing on the systems.
 
There is a LOT of rain predicted for our fishing trip. Having the motor acting up is going to make this "unfun" to be sure. I may try to do some testing while I have it down there but usually we just meet-great-fish and drink (a lot less drinking these days). We have guys coming from different states and we don't get to see each other very often. We used to take 3 trips together each year but Covid put the kibosh on that for a while. Now they don't want to take the long trip up north in the summer so we're down to 2 trips and one guy had to go to a nursing home and another passed away, so the numbers begin to dwindle.

No problem on the brain fart. I have plenty every day. My wife used to make fun of me but now she comes in the room, stands there for a while, sees me smiling and says "don't you dare say a word.." She turned 65 and has been dreading it. More doctor and dentist visits don't help her mood.

Here's my thinking on the stator. When it starts cold the stator is cold, but when it warms up the heat has expanded/weakened something and so it won't restart. What I don't understand is why it will idle at 1200 when first started, run WOT after a cold start but quit after idling back to 1200. I'm guessing that the output voltage, while lower, is much higher when it's running above 1200 than when it isn't. So it doesn't want to start after a warmup because the flywheel isn't turning fast enough. At least that's how my brain thinks it's working.

Last fall, when the problem first came up, I was idling along to the dock and I pressed the switch to turn off the accessories (VHF radio, which was turned on). When I did that the motor died and was very hard to start. I would think removing battery draw would help, but it seemed to hurt. Also last fall, when it died I could crank it for quite a while and it would eventually restart; 3 times I did this. It must have spun fast enough and created enough voltage to finally make a cylinder pop and start.That doesn't happen now. It's getting weaker each time it seems. (I know long cranking is detrimental for the starter. In the middle of Dale Hollow, in the fall, in the middle of the week with no one else around and you're about 5 miles away from the marina you get a little desperate :cool:.)

I'm competent in some areas, particularly after I have fixed something :) . (I make YouTube videos and share with others.) This area is very new to me and outboards are a pain anyway because it's so hard to test them without your neighbors getting up in arms about the noise and smoke. I am handy and fairly creative. Right now I'm pressed for time because of this trip with the boat and an overseas adventure coming up later. I don't need the boat for that so I can work on the motor before and after that. I need to get it running for the fall trip. I'll be sure to take measurements for voltage and impedance per your advice and the service manual.

>On the batt. chart, easy to see another reason starting engines in cold weather is taxing on the systems.

True, but being retired, if it's that cold I just pour another cup of coffee and go to the next crossword. :)
 
May have covered this earlier but you may be looking at a bad stator after all. Slower speeds don't produce as much voltage in magnet induced "power" systems, coils, and transformers. Slower speeds (lower frequency) generate less voltage (V=L di/dt).....long dt makes for less V. There 2 things in a transformer/coil that can reduce the V at a given di/dt and that is permeability and a shorted turn or more. Heat from running, decreases permeability and shorted turns, that didn't touch when cold, could reduce the V generated at a certain speed and be inadequate. Considering all the coils in the stator generating "house keeping voltage" and the fact that plugs fire around 18kv rather than Mercury's open circuit 40kv optimum peak value, you'd have to lose a lot of coils I'd think before you really noticed it.

Therefore I think the cold/hot testing of the blue wire ckt and red wire ckt would be your next step. Just a swag......s is for scientific.....ha ha.

Course the wires that produce the 100's of volts that are fed to your high voltage transformer connected to your plugs come from the trigger ring, not the stator! The saga goes on.
 
V=L di/dt :)
Where:
v = instantaneous voltage across the inductor
L = inductance in henries (H)
di/dt = instantaneous rate of current change in amperes per second (A/s)

Above my pay grade. You must be an electrician :)

I agree that at idle you produce less voltage (or amperage) and the heat is affecting stator and/or trigger. I think once it gets going, although weak, it produces enough electricity to fire the cylinders. Go to slow, the voltage drops and the motor stops until everything cools again.

Last night I found the voltage regulator wires connecting to the stator were burned/fused. It's the bullet connectors, they're corroding/melting. I think I'll replace them with butt splices today, at least the bad ones on the yellow wires. The wires themselves look good, but the connectors are burned. It seems to be a common problem on Mercury and not a new one either.

I was thinking that if I replace the stator I'd replace the trigger too. Once you're into something like that you should go all the way. If I can't fix it myself I'm going shopping for a motor and considering a Yamaha. My friend bought a 115 Yamaha a year earlier than my Mercury. He hasn't had to repair a single component in 30 years (Except the fuel line w/bulb), while I have a laundry list.

I have the old wiring harness and was labeling the wires last night, according to the diagram in the manual. I looked at the ones under the dash to make sense of everything. At one point I thought it was the kill switch but I'm thinking that's not the case now. I removed the black w/yellow wire from the switch box and tried to crank it a week ago and it didn't make a difference. So I'm back to stator/trigger.
 
Went on the fishing trip, had a good time, motor never started, not even a pop. Weather was warmer in Alabama than Kentucky. There weren't any 58° mornings like I had here, where the motor would start. The coldest it got was 63° and a black motor in full sun doesn't help. I don't know if that had anything to do with it or if it has finally given up the ghost.

I was sure my motor had CDM ignition but it doesn't; it has 4 coils.
The stator wires are red, blue, red/white, blue/white and 2 yellow.
The trigger wires are brown, white, black and violet

The service manual says to take these readings at the switch box, wires disconnected, for the stator and the trigger. Based on the results I think I should replace the stator. Mercury says that a bad stator can cause a switch box to fail so both should be replaced at the same time.

Thoughts? Should I also do the DVA test? Looks to me like the stator is the problem

Test Results Pic.jpg

Service Manual DVA Tests.jpg
 
I mentioned to you that your colors are not CDMs but output transformers with a switch box. If the first box herein shown, in blue and white are your Ohm tests and your results then yes on the Stator.
 
Somehow I get things in my head that don't belong there. It gets worse with age. :oops:
At least I can still take things apart and put them back together. The tools to remove the flywheel should arrive today. I've been looking for the stator, which is no longer available from Mercury, and found a CDI stator on Amazon that has the right color / number of wires and is in stock. I found one other on Amazon with the Mercury part number but it's made and sold by the same company. It's price is almost double CDI's stator. Otherwise, it's just eBay salvage stuff and another CDI stator in the UK. Amazon/CDI also has the switch box, which Mercury recommends replacing at the same time because one can damage the other.

CDI provides a very nice installation and troubleshooting .pdf that is easier to understand than the technical manual. Anyone with a similar problem should check their site for some troubleshooting tips.
 
Parts ordered. I removed the flywheel and the stator. Bench tested between red and blue wires on the stator and still have infinite resistance. I did a continuity test between the connectors and point of entry to the stator for both wires and that's good. The problem has to be in the stator. Don't know of any way to test the resistance between the red wire and engine block when it's off the motor. The stator has a metal ring for mounting but that's not showing anything. Stator should be here tomorrow and switch box on Friday. I can check the same resistance on the new one and verify it measures up before I install it.
The old one is sealed in plastic, totally black. The new one has everything exposed. I'm not sure about that but I don't have a choice. CDI is about the only ones still having the part. Connectors are different too.Stator CDI.jpgStator OEM.jpg

Total for the 2 parts is $294
 
That's not so bad. Considering its age, finding the right parts was a win win on its own.

The coils will run cooler. The core doesn't care and the wires are self protected with transformer "varnish" Assume the internal connections are soldered which will oxidize externally if not covered in a protectant, but with the low frequency involved the signals/power remain in the conductor, don't migrate to the external surface like high frequencies.....RADAR waveguide as an example.

Good luck. Keep us informed.
 
The new stator arrived and the test between the red and blue wires reads the same as the old one; infinite resistance. That's very discouraging
 
I ran a comparison test between the wires on both old and new stators. I found a seller on Amazon that provided the range of S/N that their product supported and I asked them to test between the red and blue wires.

I do find a difference between the old and new in a couple of places. One has different values and the other has no value for the old stator.

In the manual the test between the red wire and ground says that if the stator has been removed from the engine, use the black wire for the ground test. Problem is, there is no black wire, only 6; red/red-white/blue/blue-white, 2 yellow. So is the manual wrong? The manual specifies the test for my serial number in its range.20230518_194917.jpgComparison.jpg
 
It was definitely the stator. I replaced it and the switch box then went out to the driveway with the ear muffs and muffler. It fired on the first turn of the key. I let it run about 5 minutes until the water was warm, turned it off for a couple of minutes then started up again. No problems. I'm back in business. Thanks for the help and encouragement

 
Well, there seems to be a hitch. It starts and runs just fine, very fast start up. I rode around on plane to 35 MPH, about 4,000 RPM. I opened it up and as soon as it hit 5,000 RPM it stalled, not died, just stalled, and I immediately throttled back and the motor idled. I started up again and same story. I went up to 5,000 and held it there. It stalled, dropped to 4,800, took off, hit 5,000, stalled. This happened 3 times.

So I'm thinking the rev limiter, but that was replaced 3 years ago and no problem since then. I can run down the lake for a long run at 4,800 with no problem. I bump up to 5,000 and it stalls. My tach redline is 6,000 and peak HP is reached at 5,100-5,300 RPM.

I'm going to research some more, but I'm probably either going to unplug the rev limiter or buy a new one.
 
The rev limiter module has a plug on it doesn't it?
Purple wire: Switched power from the control box
Ground via the mounting method.
Brown wire: Sensor input to count pulses
Black Yellow: Ignition kill wire

Every thing is an input except for the kill wire output so I see no reason why you can't just unplug it and run. Just stay below 5250 RPM when running without it.
 
I totally agree. I have disconnected the grounding wire for the rev limiter (black w/yellow) and after Memorial Day flotilla goes home on Monday I'll take it down to the lake and try it again. Other than this problem the new parts are great. They have breathed new life into the motor. It starts and runs clean and smooth. I've never seen my motor go over 5200 RPM but I'll keep an eye on it.
 
Hi Mark, we were right about disconnecting the RL. I've posted the results in the other forum but I'll post again here for documentation:

Went to the lake today and had success in running at WOT with the rev limiter disconnected. The motor ran up to 5250 with no stalling or other problems. I ran about 2 miles down the lake at WOT, stopped, fished for several hours, then made the return run; no problems.

So it's not a fuel problem and disconnecting the rev limiter shows that the stator isn't the problem. That leaves the switch box and the rev limiter. However, in April before the stator went totally out, I was able to make the same run with the same results with OEM parts. I suspect the switch box and the vendor has offered to send me a different model of it that is compatible with my motor.

While I'm waiting for the new switch box (he said maybe 10-14 days) I'll put back the old switch box (OEM) and see if that makes it falter at 5000 RPMs. If it does, then most likely it's the rev limiter.

BTW, I was watching the tach and a couple of times when the prop cavitated because I trimmed the motor too high or made too tight of a turn it went to 5400 RPMs, very briefly before I throttled back. The rev limiter can prevent that, I think. I never had the motor falter like that before, so I don't know if the RL was ever working or not.

20230531_111852s.jpg
 
You over revved at WOT when you ventilated somewhat, reducing the load on the engine, and with the limiter disconnected you are wondering if this is normal???????
 
I was never aware of the RL doing anything in almost 29 years until I replaced the switch box and stator. After I did, when I hit 5000 RPM the engine fell on its face, then recovered, then fell on its face, etc. If the rev limiter was working before, preventing me from exceeding 5250 RPMs it didn't do it by falling on its face when I cavitated, like after I replaced the the switch box. It's a totally different behavior than if it just doesn't go any further.

So before replacing the switch box, what is the normal behavior for the RL or SB to prevent over revving? It certainly hasn't been stalling over and over.
 
I only had CDMs in my 2002 90 and 115 engines. No experience with a switchbox. My RL kicks in around 5200 per my speedometer.....accuracy???? If the RL yellow/blk......black yellow, wire is disconnected the RL is out of the curcuit unless the brown (recalling) sense wire has an intermittent short circuit in the RL. If you disconnect the sense wire too that problem is eliminated. If that is eliminated and you have a new trigger and stator then the only thing left is the switch box. What in there could cause the problem, who knows.

On your photograph, you are running in the MPH range that my boat runs....depending on the prop (and I have 4 I have run on my boat.....a 2002 Crestliner 1750 Fish Hawk), and a change in RPMs (loaded more), I run between 40 and 50, so your engine is running strong.....when it's not acting up.
 
Mercury calls it a switch box, others call it a power pack. It's the module that's mounted on the starboard side where all the wires connect; stator, trigger, RL, etc. When my rig was new it would do 52 on the speedo, now it's just 45 and sometimes slower. RPMs at WOT are 5200 with the RL connected or disconnected, same as when new. Lower unit was replaced last year. I don't know why it won't go up to 52 anymore. I've taken everything out of the boat and tried it; no difference. Last year 42 was tops but so far this year it's 45, even with the old stator and switch box, before the stator failed. I have a 4-blade I put on if I have multiple passengers. It helps with getting on plane, especially with a full live well. Max RPMs with that is about 4900.

I'm glad it's running again, with no issues, but I'd like to get the RL connected again.
kon_200510_tart_king.jpgSwitchbox.jpg

I have a 1995 Ranger R72.
 
I put the OEM switch box back on the motor and took it out fishing today, RL wire connected. The motor acted the same way as with the new switch box. So the problem is apparently with the RL and not SB. I told the vendor to cancel his freebie offer of a different SB. The RL is only 3 years old and came from a Mercury dealership in FL. They do not respond to my emails. I think they may be out of business.

Everything else seems to be okay and I'm happy with the motor's performance.
 
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