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Mercury 1995 115 runs at WOT, dies below 1200 RPM

richw46

Member
My 1995 Mercury 115 started having problems last fall. After a long run to the marina when we got into no wake and I slowed to 1200 RPM it was putting along fine. I dropped to 1000 RPM and it immediately died and refused to start. (Died like the kill switch was pulled or key was shut off.) I kept cranking and it eventually fired but almost ran the battery down. I parked the boat and the next morning it started normally and I put it back on the trailer

Winter came and the boat was put on jack stands in my garage

This week I did the normal spring routine including changing the spark plugs. Yesterday I took it to the lake and it started on the first crank. I ran up to 45 mph with no problem, slowed, U-Turn, went at half throttle to my first spot. As I approached the RPMs came down to 1200, idled in gear ok, dropped to 1000 and the engine died again and wouldn't start even with prolonged cranking. I fished for maybe 20-30 minutes, cranked the engine and it fires up. I go to the next hole and again, it dies at 1000 RPM. This happened one more time and then it refused to start any more. I went to the dock on the trolling motor. At the dock I cranked and got a blue-smoke sneeze and that was all.

I'm pretty sure this isn't a fuel problem because it's an immediate stop. The first time it happened I choked it and it just flooded the engine. After that I just turn the key and either it will start within a few seconds or not at all. It seems like it will start after it has been sitting a while, like something needs to cool off. First crank in the morning is always successful. I don't think it's the kill switch in the shifter because switching it on-off doesn't make a difference, but it might be something else in that circuit. In my service manual it shows a black wire that runs from the switch to the motor in one direction, to the ignition switch in the other. There is also a yellow/black wire from the switch to the ignition.

I have a fishing trip coming up in 3 weeks and of course now it acts up. I'd appreciate any help I can get.
 
I don't have my service manual handy and I don't remember if it starts with the 1994 or 1996 and up models of the 60 Jet through 125 HP engines. Assuming that the '95 is somewhat similar to my '02, a shot in the dark, maybe a stiff diaphragm in the fuel pump. Being able to make 45 MPH, which reflects my 115's (working like a well oiled clock) top end with the 5250 rev limiter, tends to reflect otherwise, but maybe there is enough crankcase pulse energy to take care of the top end.

The other thing would/could be clogged fuel lines or fuel filters....both the main one and the little 3 and 4 cylinder filter hiding behind the rear of the oil tank.

Since those RPMs are using 1 and 2 only, the small filter wouldn't be suspect but if changing I'd do both. Other thought might be cracked fuel lines which would manifest themselves by finding fuel around a line, especially at the hose barb connections. At high RPMs the fuel pump may be pumping enough fuel that they aren't noticeable but at low RPMs with a stiff diaphragm not enough to supply enough fuel to overcome leaks.

I don't think I would be chasing an electrical problem here....fuel related. But this is all conjecture since I never experienced/heard of such, and I'm obviously open to criticism. Bring it on....might do all of us some good. Good luck!
 
I don't have my service manual handy and I don't remember if it starts with the 1994 or 1996 and up models of the 60 Jet through 125 HP engines. Assuming that the '95 is somewhat similar to my '02, a shot in the dark, maybe a stiff diaphragm in the fuel pump. Being able to make 45 MPH, which reflects my 115's (working like a well oiled clock) top end with the 5250 rev limiter, tends to reflect otherwise, but maybe there is enough crankcase pulse energy to take care of the top end.

The other thing would/could be clogged fuel lines or fuel filters....both the main one and the little 3 and 4 cylinder filter hiding behind the rear of the oil tank.

Since those RPMs are using 1 and 2 only, the small filter wouldn't be suspect but if changing I'd do both. Other thought might be cracked fuel lines which would manifest themselves by finding fuel around a line, especially at the hose barb connections. At high RPMs the fuel pump may be pumping enough fuel that they aren't noticeable but at low RPMs with a stiff diaphragm not enough to supply enough fuel to overcome leaks.

I don't think I would be chasing an electrical problem here....fuel related. But this is all conjecture since I never experienced/heard of such, and I'm obviously open to criticism. Bring it on....might do all of us some good. Good luck!
Edit: Cut the large filter open and observe the contents. If black specks, internal fuel line failure. If tan, "crispy" components, fuel line from tank to engine has failed.
 
Hi Mark, thanks for the reply. I replaced the filter on the port side along with the fuel hose/ bulb in 2020. The engine runs smoothly at full throttle or slower as long as I don't drop below 1200 RPM. Even so, when it will start it idles normally. It never seems starved for fuel. I put new kits in the carbs in 2019 and replaced the oil bottle about the same time. When it sits for a while or when it's first time for the day it starts right up, no hesitation. Take a run down the lake, a couple minutes, slow down but on plane runs smoothly, drop to 1000 RPM and it's like you turned the key off; no stutter or other signs, just stops and won't restart for a while.

I think I know how to disable the kill switch at the motor, so I'm going to try that. I don't know if I can replicate the problem in the driveway or not. May need to take it to the lake
 
Thanks for the feedback. Not being there I have done what I can do. You still haven't addressed the fuel pump potential problem. Do a kit on it and test then come back. You didn't answer my question about the main filter's contents.
 
The filter is pretty new (10/2019) and the old one was about 16-17 years old and was clean. I haven't removed the oil tank to check that other one yet. I put the ear muffs on this afternoon and it fired on the first crank. Shut down with the kill switch, fired it up again. I did this several times and the last time I let it run for a minute. Won't start again. I had read that disconnecting the black with yellow trace wires would bypass the kill switch, but if it does, it doesn't change anything, so maybe not the kill circuit. Fuel line and bulb were replaced in 5/2018. Water separator 9/2014 so that's overdue. New kits in the carbs 10/2019, new oil tank and rev limiter 6/2020.

I will open the fuel pump and take a look at it. I just wanted to try someone else's suggestion which was easier to perform. I can discount that and move on to the next one.

When this happened last year, after I got it started again I drove several miles back to the marina at about 3/4 throttle without incident. As soon as I arrived and slowly dropped the throttle it was okay until that 1000 RPM mark. When the motor cools it will start and run until it gets warm AND you get below 1000, but as long as you don't drop down it will continue to run. To me, it just doesn't seem like a fuel problem if I can go for miles.

Mark, I do appreciate you're help in this. Outboards are temperamental things. Someone else suggested testing the output of the stator but he says it's not 60 hertz but rather a 1000 and I don't have a meter for that. I'm starting to get the impression that it needs to go to the shop and I'm sure they can't fix it for at least a month or two since everyone has theirs in for repairs.

Plan B???

Thanks again
Rich
 

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The stator is a transformer coil energized by a magnet pasing by on the flywheel. Output voltage is inductance X rate of change of induced current/time of cycle (RPMS)......the faster the flywheel turns the shorter the time element and higher the voltage. Iterating, if it cranks at 200 it will run a 1000! There aren 't mechanisms there to cause your problem.

Back to the fuel pump. When I replaced the one on my 2002 when I bought this boat several years ago the diaphragm was stiff. If the one in your '95 is the original, or had been replaced once, it too should be stiff. Do a fuel pump kit repair.....don't just look at it...not difficult, just follow the directions that accompany the kit especially paying attention to the placement direction of the valves. If you had pressure pulse problems from the cylinder I think it would be a constant thing, not intermittent.
 
Thanks, Mark. I have ordered a fuel pump kit and it should be here mid next week. I'll do the build and driveway test it. I'll let you know how it turns out.
 
I rebuilt the fuel pump yesterday and did a driveway test today; no good. Starts and runs fine at an idle, even at 1,000 RPM, no problems. Turn it off and try to start it again and it won't. I put a timing light on the top cylinder and cranked it. The light flashes so I know it's getting fire.

I'm still convinced that somehow it's electrical. When it stops it's just like you turned the key off and it won't restart (although it seems to idle for quite some time at 1,000 RPM). No use in going to the lake if it fails the driveway test. I don't know anything about the stop circuit but I feel that the problem is tied to that somehow.

I had heard that you can disconnect the black wire(s) w/ yellow tracer on the switch box and it bypasses that. I tried that but either it's not those wires or it's not working. In my service manual it shows a black wire going from the kill switch through the wiring harness to the engine and from the kill switch to the ignition plus a yellow w/ black tracer going from the kill switch to the ignition switch. It's probably not a safe thing to do but just to get me past this upcoming trip in a week I'd like to bypass the kill switch; disconnect, unplug, whatever.
 
I was just thinking this morning, if there is spark in the piston then the only other thing missing is fuel, so it has to be fuel. Then I was thinking about how the fuel pump works. It has a fuel line hose connection between the motor and the fuel pump. That's the original pulse hose. Maybe it has an air leak? It's pretty stiff. I'll get some new hose and see if that makes a difference. If that doesn't help it then I'll try squirting some fuel into the carburetors.

If none of that works then I'll have to go on my fishing trip 'as is' and make an appointment with the repair shop, cause I'm out of ideas.
 
Do the following test.----Does spark jump a gap of 3/8" on all leads , yes or no ?-----The bottom 2 carburetors do not provide much fuel at idle.----The motor only idles on the top 2 cylinders.----Bottom high speed circuits kick in at about 1800 RPM.
 
This is a 2+2 motor. The bottom 2 cylinders don't get fuel until 1800 RPMs, just oil, bottom carbs don't have idle screws. (New kits in all 4 carbs in 2019.) At 1800 RPM the accelerator pump sends a squirt of fuel to the bottom 2 and off she goes. If it will start and idle I can go to WOT without any issues and it will idle when it's cold/first started. Plugs are new, gapped at .040. It will idle along okay cold at ~800 RPM, get up on plane and run fine. Throttle back to below 1200 RPM and it stops, like you turned off the ignition or pulled the kill switch. Let it cool down for 30-60 minutes and it will start again; driveway or lake. Other than it's refusal to restart there is no indication of any problem with the motor. If it starts it runs quite well

When cold, I can set the kill switch to kill and it won't start. Set it to run and it will fire right up without hesitation.
When it's warm and you shut down it won't start, even with the timing light flashing. You can choke it and it doesn't make a difference. There's no pop, spit or other indication that it's trying to fire up; nothing, just cranks.

I don't think it's the CDI or plugs or it wouldn't run as smooth as it does. I thought it was in the stop circuit for a while but now I'm with TexasMark, thinking it's fuel. I rebuilt the pump and it hasn't made a difference. The hoses on the pump are very old and stiff so maybe the pulse line can't pulse??? I'm going to replace it with some different fuel hose (yes, it's old too but softer than what's on the pump) and zips and see if that makes a difference. I was also thinking about removing the attenuator cover and squirting gas in the top carbs. It's warming up a bit now and the sun is out. I will try these things and post results
 
It's cold, windy and rainy outside. It's going to be that way for a couple of days. I'm thinking Wednesday I'll be able to pull it outside again.
 
I might be able to do it in the garage.
The boot is 3/4" long. Do you put something inside the boot and measure from that point? I'm not sure how I can measure 3/8" of spark. I assume you let it spark to the block
 
You can glue 2 pieces of wire ( even pieces of toaster wire ) on a piece of carboard.----A 3/8" gap between them.---Stick one end in the plug boot.---Other end grounded on the block.
 
I don't see any spark, no matter how close the wires get. I still see the timing light flashing using the same wire connected to the spark plug. The motor fires immediately when it's cold, let it run for a couple of minutes and shut it off, immediately try to turn it on and it won't start, timing light flashes.

20230502_124624.jpg
 
I’ve been working on the motor for several days and it has me stumped. I called the only repair shop in town and they aren’t even taking reservations. They are booked through June. One of their mechanics agreed to talk with me and I described the symptoms. He asked numerous questions but wasn’t able to provide any new options. The fact that the motor will start and run without any issue but won’t restart immediately after being shutdown is puzzling. The timing light flashes when it won’t restart so there’s spark, which wouldn’t happen if the kill circuit was active. I’ve rebuilt the fuel pump, which had no sign of any foreign matter in it. I replaced a fuel line that does the push-vacuum from the block to operate the pump. I thoroughly cleaned the wiring harness connection to the motor from the console. When it gets cold again it will start and run until the idle is below 1200 RPM. When it won’t start I have squirted gas mix into the carburetors; not even a sneeze or cough.

Compression test 10/2017 was good - 115-120 on all 4 cylinders
Brand new spark plugs gapped at .040 last week
Replaced external fuel line in 05/2018
Rebuilt all 4 carburetors with new kits 10/2019
Fuel Filter 10/2019

I’m going to stop work for now and find a repair shop in another city. I was given a lead on a mechanic.

Here's a link to the YouTube video I made, just a minute and 25, very short.
I pulled it out of the garage, hooked up the water and turned the key, no choke or throttle advance. It started up and I let it idle for 4-5 minutes, turned it off and tried to immediately start it; no joy. I waited 3-4 minutes and tried again; no joy.

Thanks for the help
 
Agree that if your timing light flashes your kill circuit isn't killing your CDIs.

Remove the plastic baffle in front of the carbs and get a can of Sea Foam Aerosol....ww has it. Start the engine cold and shut it down like you usually do. Try to start it again and while the starter is turning the engine, immediately spray a 2 second shot of SF onto both top carbs. If it lights off, its fuel. If it doesn't then you may have enough spark to fire the light but not enough to fire the plugs.

As Racerone said, you need to check the intensity of the spark and check it on 1 and 2 looking for equal gap jumping. I like the idea of a couple of wires taped to a piece of cardboard, with the tips raised and positioned such that you can start with a 1/4" gap and if that works work your way out. You need a good connection in the spark plug boot and on the ground, get on a SS screw or better yet, scratch off some paint and put it there. Under the ground screw on the regulator black ground wire would be a good place.... remove the screw and sand off the plate nice and clean. Put the wire under the screw and tighten it down. While you are at it, check all cylinders.

On low RPMS and 3 and 4 the fuel and oil are fed to those cylinders since you are mixing the two at the inlet hose or you are using premix....little clarification. Enough for cylinder lube but not enough to cause any power from those two cylinders.....your ignition is normal for all 4.

Running magnetic devices can have problems like chafing which can cause problems in the magnetic circuit. A guy on the farm forum is having a similar problem with his conventional ignition coil on his tractor and I explained the internal process to him.

The service manual shows you how to check the stator output voltage with a sample and hold circuit (that you can build) attached to a DVM. The service manual tells you what to do and what parameters are pass and fail. The pulses are very narrow and the rest time is very long. The DVM can't read that alone but if you add a probe with a storage device and blocking diode the capacitor will charge to the peak value, hold it long enough for you to get a reading on the DVM. I could tell you how to do it and what value to seek and where to look but my manuals are out in the shop. The 3 parts needed plus some wire should be accessible on the www.....capacitor, diode, bleeder resistor, wire, solder and an iron....plus the DVM (Digital Volt Meter) Harbor Freight has them for less than $10.

Therefore if you prove to yourself that it isn't fuel related.....fail the Sea Foam test, then go after the stator failing due to heat caused by an internal malfunction.
 
Agree that if your timing light flashes your kill circuit isn't killing your CDIs.

Remove the plastic baffle in front of the carbs and get a can of Sea Foam Aerosol....ww has it. Start the engine cold and shut it down like you usually do. Try to start it again and while the starter is turning the engine, immediately spray a 2 second shot of SF onto both top carbs. If it lights off, its fuel. If it doesn't then you may have enough spark to fire the light but not enough to fire the plugs.

As Racerone said, you need to check the intensity of the spark and check it on 1 and 2 looking for equal gap jumping. I like the idea of a couple of wires taped to a piece of cardboard, with the tips raised and positioned such that you can start with a 1/4" gap and if that works work your way out. You need a good connection in the spark plug boot and on the ground, get on a SS screw or better yet, scratch off some paint and put it there. Under the ground screw on the regulator black ground wire would be a good place.... remove the screw and sand off the plate nice and clean. Put the wire under the screw and tighten it down. While you are at it, check all cylinders.

On low RPMS and 3 and 4 the fuel and oil are fed to those cylinders since you are mixing the two at the inlet hose or you are using premix....little clarification. Enough for cylinder lube but not enough to cause any power from those two cylinders.....your ignition is normal for all 4.

Running magnetic devices can have problems like chafing which can cause problems in the magnetic circuit. A guy on the farm forum is having a similar problem with his conventional ignition coil on his tractor and I explained the internal process to him.

The service manual shows you how to check the stator output voltage with a sample and hold circuit (that you can build) attached to a DVM. The service manual tells you what to do and what parameters are pass and fail. The pulses are very narrow and the rest time is very long. The DVM can't read that alone but if you add a probe with a storage device and blocking diode the capacitor will charge to the peak value, hold it long enough for you to get a reading on the DVM. I could tell you how to do it and what value to seek and where to look but my manuals are out in the shop. The 3 parts needed plus some wire should be accessible on the www.....capacitor, diode, bleeder resistor, wire, solder and an iron....plus the DVM (Digital Volt Meter) Harbor Freight has them for less than $10.

Therefore if you prove to yourself that it isn't fuel related.....fail the Sea Foam test, then go after the stator failing due to heat caused by an internal malfunction.
Backing the truck up, I took another look at your input and your spark gap. I got involved in thinking my way through what I was going to say (81 year old had a brain fart) and forgot about your test rig. I was going to edit my post but I had passed the 5 minute time allowed for editing.
I have a couple of comments:
1. arcing HV works better coming off sharp points if you separate your wires stapled to the 2x4 to about 1 1/2 to 2" ....distance they are apart at the board......just grasp your ground wire and pull it back in the existing stapled mounting. Bend the tips toward each other such that the pointed tips are facing each other...sharp points like where your dikes cut the wire. The point to be made here is that you are concentrating the voltage along the wire to one point, not spread out along the smooth surface of the exposed wire. Measure your gap there and start with a short distance to ensure the other connections are adequate then work your way out. If it will jump 1/4, space to 5/16, and then 3/8 (as Racer one said).

2.I can't see where/how you secured the other ends of the wires in your photo. Would like to see that.
 
I found some articles this morning about the stator. One symptom of a failing stator is pretty much my symptom; cold start okay, warm start fails. I don't have the tools to pull the flywheel but I'm considering doing it. I have a decent multimeter (KAIWEETS HT206D Digital Clamp Meter T-RMS), an old multimeter from Radio Shack (great in its day) and a couple of HFT freebies. None of them will do what the service manual says it needs, to read the top voltage from varying voltages. I think that's what a DVM can and there should be a scale or separate jack on the multimeter for that.

My spark rig is grounded to a bolt on the voltage regulator. The positive is plugged into the top cylinder plug wire.

I think what you're saying about the voltage being enough to light the timing light and not enough to spark the plug is probably right. Something I haven't tried is having the timing light flashing with the motor running to see if the light is brighter. I had an old timing light that got it's power from the spark and was very handy in diagnosing a weak spark because of that; long gone.

A new motor would run me in the $10K range and if they take anything off for a trade in that would help.
Mercury recommends replacing the switchbox if you replace the stator. I know a switchbox is about $500, the stator at $400 on Amazon. Throw in labor and maybe a trigger for another $100, I'm guessing $1500 to $2000 for the repair. It's a 29 year old motor this fall, still runs really well and probably low hours.

I don't want to do anything now, waiting until after the fishing trip next week. I'll get a multimeter that can do the DVM test and take a few more readings. I don't have any more fishing trips in the offing so I can work on it this summer. I think I'll visit the Mercury dealership too, maybe Yamaha.
 
BTW, I squirted some gas mix into the top 2 carbs, plastic cover on, plastic cover off. Nothing, just cranked. I was thinking of maybe a shot of starting fluid in each
 
On the timing light brightness, V (to operate the bulb) = L di/dt, L being the inductance of the pickup coil which should be a constant and di/dt being the rate of change of the pulses as the magnet passes the coils. Expect it to be brighter at 650 normal idle speed vs 200 cranking speed with a fresh battery.
 
BTW, I squirted some gas mix into the top 2 carbs, plastic cover on, plastic cover off. Nothing, just cranked. I was thinking of maybe a shot of starting fluid in each
Starting fluids usually, in the past anyway, didn't contain oil. Boating forums recommended SF because it had oil and enough hydrocarbons to ignite. So, if you did the squirt test and no results then seems to me its stator test time.
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Attached is a long file but down the article a way is the schematic for the DVA (not DVM....that is what reads the output of the DVA...digital voltage adapter) unit. The bottom line is engine block ground. The input is on the left and is an alternating (AC) pulse. The diode is setup up to measure the peak value of the + half of the alternating signal input.

Every time the AC signal forward biases the diode it conducts current and energy is dumped into the capacitor (sampling) and the capacitor starts filling up with energy (hold). After several seconds, the capacitor will have charged to the peak of the AC input. The resistor is a bleed resistor to eventually bleed off the charge after the test. The meter leads attach to the right hand top "signal" and bottom line (ground), red lead to the top + and black to the - of your DVM....some people refer to them as DMM...digital multimeter as they are digital and measure numerous things.

My HF cheapie DVM has a 500 and 1000 DCVoltage scale. I don't remember the value of the readings but after awhile today I will go out to the shop and get the numbers from my SM. I'll identify the test points in the wiring harness also.....where you hook up the signal lead.....you know where the ground wire goes.

The article should put you onto the 3 necessary components.
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I think it takes a 1 1/16 inch socket to fit the flywheel nut and a 1/2" impact tool with at least 100 PSI behind it will remove it.....installation torque when you finish is 150 ft-lbs as I recall....impact can do that for you too. HF has wheel pullers also. look at the hole spacing on top of the FW and get a puller that fits those holes. If it doesn't want to move, don't beat on it with a hammer......banging degauses the magnets in the underside of the FW. A little heat on the FW around the crank shaft will help expand the aluminum before the steel crankshaft has had time to move.
 
Thanks, Mark. Excellent information. I typed DVM when I meant DVA; oops, senior moment. You are way ahead of me on the timing light brightness but it definitely makes sense. I used the old timing light on an old West Bend long ago. Did the top cylinder and it was nice and bright. Did the bottom cylinder and it was about half that bright. The motor ran so we were happy. Extremely hard to get parts for it in the 80s. I agree on the squirt test; not so much as a burp so I'm thinking stator.

I found a couple of YouTube videos too on how to make a DVA. I have a meter that has a setting for peak voltage reading. I'm not sure if that's the same as the DVA. It can handle 600 VAC or VDC and can do the peak voltage on AC or DC. I'll look at what HFT has. I'll check the shop manual for the torque. I think my torque wrench goes to 150, something else to check.

I have the Mercury part numbers for the necessary tools as well, and I have a HFT electric impact drill. If that doesn't do it I'll either buy or rent one. I found Amazon tools with good reviews, including for my MY of 115 Mercury and much cheaper than Mercury, except for the CDM test harness, which I'm not sure I'll need. I think the CDMs are good. They sure try to gouge you when a part or tool is no longer available (NLA).

Thanks for all the great information

ToolMercury originalMercury nowAlternative on Amazon
Flywheel holder 91-52344 (NLA)$55$200+$28 (Lisle)
Flywheel puller 91-849154T1 (NLA)$14.75$175$16 (Zinger)
Spark Gap Tester 91-63998A1$45$45$10.30 (Lisle)
TPI/CDM Test Harness 84-825207A1$108$108$106 (Boating Acc. Inc.)
 
I got my manual out and it starts at '94 models and goes up through my '02. There isn't a lot on the pre-97 engines which use a common box (switch box) for doing all the charging and triggering and send a high voltage pulse and ground to a separate high voltage transformer connected to each plug. My engine comes off the capacitor charging coils and trigger directly to separate CDI....Capacitor Discharge Ignition modules.

Looking where I have never been before, with the switch box at low speeds ( a speed you can obtain with the caps on the plugs and out of the engine with the cases grounded (taped to block, or wrapped with a ground wire around the threads, and a fresh battery.

Put your DMM on a scale greater than 400 Vdc. The capacitor charging voltage should a minimum of 180V for capacitor charging at that cranking speed. Faster the engine turns higher the voltage. They are identified: One coil output is the blue and blue/white (stripe). The other is red and red/white. You should have easy access at the switch box connectors.

Triggers are 4 wires colored brown, white, violet, and white/black. Since the manual diagram isn't very clear, shows 2 trigger coils for your engine, I would Ohm out brown to white or white/black checking for continuity and run the same test for the other two wires that you haven't measured and obtained continuity. Again easy access should be at the switch box connectors. Put your DMM on a 10 Vdc scale and get across the pairs of wires showing continuity. Crank the engine and the voltage should be greater than 3v for triggering.

I'd run these tests cold and then put your plugs back in, remove the test equip. and run the engine long enough to get it hot enough to show your malfunction. Shut it off, pull plugs as mentioned above and re run your tests. Check back with your results.
That's the best I can do since I don't have your engine and never ran that test.
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The confusion on the size of the capacitor in the test set www verbiage is no biggie. I used 1 microfarad at a voltage (DCWV) greater than 400V and it worked just fine for my testing. The larger the cap the longer it takes to fill it up to a stable reading and longer it takes to discharge. The diode is nothing special, just a small 1 amp or so diode with a PIV rating over 400V. The 1 megohm resistor could be any wattage or type....just something with enough resistance to not effect your reading yet bleed the cap of its charge when finished.

Edit: Everybody referrs to the Stator as the thing under the flywheel. The stator charges the battery. Additionally are the triggering coils (separate component), both high voltage to charge the capacitors that fire the spark plugs plus the coils to trigger the discharge function.
 
Thanks, Mark. Excellent information. I typed DVM when I meant DVA; oops, senior moment. You are way ahead of me on the timing light brightness but it definitely makes sense. I used the old timing light on an old West Bend long ago. Did the top cylinder and it was nice and bright. Did the bottom cylinder and it was about half that bright. The motor ran so we were happy. Extremely hard to get parts for it in the 80s. I agree on the squirt test; not so much as a burp so I'm thinking stator.

I found a couple of YouTube videos too on how to make a DVA. I have a meter that has a setting for peak voltage reading. I'm not sure if that's the same as the DVA. It can handle 600 VAC or VDC and can do the peak voltage on AC or DC. I'll look at what HFT has. I'll check the shop manual for the torque. I think my torque wrench goes to 150, something else to check.

I have the Mercury part numbers for the necessary tools as well, and I have a HFT electric impact drill. If that doesn't do it I'll either buy or rent one. I found Amazon tools with good reviews, including for my MY of 115 Mercury and much cheaper than Mercury, except for the CDM test harness, which I'm not sure I'll need. I think the CDMs are good. They sure try to gouge you when a part or tool is no longer available (NLA).

Thanks for all the great information

ToolMercury originalMercury nowAlternative on Amazon
Flywheel holder 91-52344 (NLA)$55$200+$28 (Lisle)
Flywheel puller 91-849154T1 (NLA)$14.75$175$16 (Zinger)
Spark Gap Tester 91-63998A1$45$45$10.30 (Lisle)
TPI/CDM Test Harness 84-825207A1$108$108$106 (Boating Acc. Inc.)
Peak voltage reading voltmeters were and were called Vacuum Tube Voltmeters back in my early days as compared to something like a Simpson Analog meter using a D'Arsonval jeweled meter movement and mirrored needle...for accuracy and a battery vs AC voltage to operate (on Ohms scale for the Simpson). In using those I don't recall trying to measure a 10-40 microsecond pulse that occurs 1/200 times a minute.

For that kind of money, if your flywheel doesn't have threaded holes for a puller attachment, I'd drill and tap a couple of holes but be careful not to break out and hit your electronics below. But your money, your choice. Good luck.

Run the tests I mentioned before you fool with removing the flywheel.
On the test harness, since it appears that the '95 has the switch box, you have easy access to your test points. My '02 has the CDMs and the test harness would be very beneficial....or just slit the insulation on a wire and tape it back when finished.
 
Okay, thanks Mark. Like I said earlier I'm getting ready for a fishing trip next week and don't have time to do anything else to it right now. I think the flywheel is tapped. I found a review for the flywheel puller by someone who had a 95 115 Mercury and he said it fit his and he was able to get the flywheel off.

I'm definitely going to either build a DVA or buy a meter with one. I've done electrical work in the military on Huey and Cobra gunships, built my first depth flasher with a Heathkit kit and a few test kits for various things; should be fun.

Will certainly do testing to make sure it's the stator. My service manual has procedures. I think Mercury calls them switch boxes and the others call them power packs. My service manual says switch box and shows CDMs for my MY and 4 cylinders.

Thanks
 
Okay, thanks Mark. Like I said earlier I'm getting ready for a fishing trip next week and don't have time to do anything else to it right now. I think the flywheel is tapped. I found a review for the flywheel puller by someone who had a 95 115 Mercury and he said it fit his and he was able to get the flywheel off.

I'm definitely going to either build a DVA or buy a meter with one. I've done electrical work in the military on Huey and Cobra gunships, built my first depth flasher with a Heathkit kit and a few test kits for various things; should be fun.

Will certainly do testing to make sure it's the stator. My service manual has procedures. I think Mercury calls them switch boxes and the others call them power packs. My service manual says switch box and shows CDMs for my MY and 4 cylinders.

Thanks
Trigger circuit, not stator...mounted inside the inside diameter of the stator that charges the battery. It has a lever arm attached that goes to the throttle control.....since timing runs from about TDC at idle to 20-22* BTDC at WOT. Easy to determine which type, color code of wires and Large switch box or no box and 2 a wire connector HV transformer for HV to the spark plug. Serv. Man shows that 1997 is when they changed to the CDMs, making them larger, more input wires, changes in wiring color codes, and deleting the switch box.

On the flasher......small world. I too bought a Heath Kit for my first flasher. It was light enough and could use a small enough battery that I could take it with me, hand carried on pier fishing trips. Worked great considering it was a Neon bulb. Boy has that function changed.......I was watching a bass tournament yesterday and the fancy gadgets they have now......fish don't have a chance.
 
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