1984 Mercury 50 HP will not Plane

My 1984 Mercury 50 hp Outboard seems to run fine when starting and running in neutral, however when I try to accelerate beyond 6 mph the engine falls on its face and does not recover without backing off the throttle...

Tests I have performed and the results are as follows: (All of these test were performed at Cranking Speed. Not Running)
1. Compression test (Ft Lbs): #1=140, #2=150, #3=140, 4=140
2. Coils (Ohms): #1=.2, #2=.2, #3=.25, #4=.25
3. Stator (DVA): 218V
4. Trigger (DVA): 3.749V
5. Trigger (Ohms): Brn to Wht/Blk = 792 & Wht to Vio = 798
6. Verified All Plugs were firing as expected.
(Based on the information I have, the results above appear to be within range.)

Tune-ups:
1. Cleaned both Carbs.
2. Kitted both Carbs., with New Needles.
3. Adjusted Float Leaves.
4. Replaced All Plugs

Test I believe I still need to do:
1. All of the above tests with the Engine Running.
2. Check Timing.
3. Verify, with Timing Light, what cylinders are firing based on each plug wire.

With consideration of the results above, are there any specific tests that should be focused on more than any other to address this type of issue?

Thank you in advance for any expertise you may provide.

Last one I worked on had the exhaust tuner 2/3 plugged with carbon.----Also the bottom crankshaft seals and bottom bearing were bad.-------Dealer had installed all new electronics to try and fix the performance problems.-------Trouble shooting has gone the way of the dodo.

Thank you for your response... I will give these a try and see what I find. I do have one question/concern regarding the "Cylinder drop test".
I have done this type of test many time on Automobiles, to isolate cylinder specific issues, however I have seen many posts that repeatedly talk about damaging the ignition system when the plug wire is not grounded. Are these mostly "Disclaimer" type responses or is this type of damage more common on this type of ignition system over that of an automobile?
Thanks again for your response.

racerone said:

Last one I worked on had the exhaust tuner 2/3 plugged with carbon.----Also the bottom crankshaft seals and bottom bearing were bad.-------Dealer had installed all new electronics to try and fix the performance problems.-------Trouble shooting has gone the way of the dodo.

Click to expand...

I will take a look at this as well. Thank you for your reply.

Went out to do the "Cylinder Drop Test" and the Starter was acting up, so I tore it apart Clean all internals, polished contacts and put it back together. Click... Click... Click... Tested Voltage on solenoid and it was occasionally registering 1 - 2 Volts... :-( Tore the Solenoid apart and found contact that had been fried, at some point prior to me owning the boat... Filed and Polished the Studs, turned the Contact Disk over and reassembled. Now it reads comparable voltage to the battery... Now Starter cranks every time...

Finally back to the "Cylinder Drop Test"... I got all Coil Leads ready for a quick removal from the Coils, by moving the boots up the wires. Although I have done this barehanded before, I elected to use some insulated pliers to lessen the jolt or at least I though they were insulated right up to the point that I tried to pull the wire on the second coil... ZAP!ZAP!ZAP!!! I found that I just barely had to even touch this wire and it was more than happy to give me a thrill.
Anyway, After making this discovery, I elected to try anther simple test and sprayed a fine mist of water, from a squirt bottle, in the general direction of each Plug and its Spark Plug Boot. This immediately sounded like I had just pored milk on a Big Bowl of Rice Krispies... Huston I thing we have a Problem...

I am going to replace all of the Plug Wires and noticed that the ones that were on it were "Solid Core". I do not believe they were original equipment, but I was wondering if I should use "Copper Core" Spark Plug Wires or just go with a Good Quality 8mm Spiral Wound Low Resistance Set....

Is one recommended over the other for these motors?

Thank you...

After replacing all Plug Wires, I attached a Inductive Pickup Tachometer to each of the cylinders and could not get a consistent reading from any of them...(It was changing so fast that I could not get any reading...)

I also indexed each Cylinder marking the corresponding number, on the flywheel, when it was at TDC. I then connected a Timing Light to each Cylinder and found that each Plug was flashing Multiple Cylinder Numbers rather than just the Number of the Cylinder I was connected to. In most if not all cases the Number for the Cylinder I was testing had the Strongest Visibility, over any other Number that was visible, but I still do not believe this is correct.

Considering the statistics I posted at the begging of this thread, appeared to be within normal acceptable limits, I am now trying to determine if I have a Stator, Trigger or Switch Box Issue. I have the service manual and will continue to read through it to see if something stands out, but if anyone happens to have a sure-fire test procedure that has a reasonable expectation of identifying the culprit, I would greatly appreciate it.. I would much rather through hundreds of dollars towards rebuilding the Decks, Carpet, Seats, Console, etc... over throwing it away on any one of the electronics only to find it did not solve the problem

I am not sure if it matters, but the motor currently does not want to idle either, like it is loading up... It starts without a problem and will run if the throttle is positioned just above an idle. I assume this is related to the ignition issues that appear to be happening, but I figured I would throw this in the hopper as well... (Please recall that I just Cleaned and Rebuilt Both Carburetors... I measured and adjusted both floats and I Tuned Both Air Screws as best they could be tuned under the current conditions. I have many years of experience with Tuning My Motorcycle Carbs, so I am reasonably confident that the "Major Issue" is not being caused by Carburetor Adjustments.)

I am not ready to throw in the towel, just yet, and would greatly appreciate any help in narrowing down this issue...

Thank you in advance for reading my post and for any assistance you may be willing to offer...

At what rpm not speed does this happen??? If its arounfd the 1800-2000 rpm range the stator could be dropping the high speed out...

Unfortunately I cannot get an accurate reading, on the RPM, since the Inductive Pickup Tachometer I am using is changing the readout so fast that there is not a number to be read. (I am not sure if this is caused by the random firing issue I indicated above or just the electronic noise from the Solid Core Spark Plug Wires...)

Anyway, if I had to guess I would say it would be in that range or slightly above...

With each cylinder's number marked on the Flywheel, at TDC, is it not uncommon to see more cylinder numbers than the one the timing light is connected to?

I am not sure if this matters, but it appears the prior owner has put a Red Stator Kit on at some point in time... I am not sure what the significance is of using a Red Stator Kit, but I see it mentioned on many threads.. Although I do not know when this was done, it does indicated that it was change at some prior point in time...

As I am not technically versed on the different stages of stator output, it stands to reason that if a stator has a Low Speed and High Speed output then I am being fooled by the readings I have got at low speed...

I will try to configure something that will allow me to test the output when I hit the RPM Problem Area, to see if I can notice an out of range DVA reading... I assume this will need to be performed under load, as the problem does not appear to happen when in natural... I think I am fixing to get wet...

Thank you.

I will still check, but I just read a Post, from CDI Electronics, that indicated the Red Stators do not have a Low and High Speed Winding... Does this make a difference on the theory of Low versus High Speed drop-off?
Thanks again for your reply.

You may have a bad stator adapter test below........

http://1manual.com/Mercury manuals/Service Manual PDFs/TwoStroke/817643r1/2a.pdf

Interesting Development...
I elected to pull the Flywheel to determine the condition of the Ignition Components and was surprised to see everything in Like New Condition... They were not just clean but almost look like they were just put on the Boat before we bought it. The prior owner indicated that the boat was not able to get up to speed and did not know what was causing it, but did not indicate if he had replaced any parts... I assumed the Carbs needed cleaning, as it idled fine, which is why kitting them was the first thing I did.

I confirmed it has the Red Stator Kit, but the tag on the wiring harness has unglued and is gone. I can only assume it is the 398-832075A20 kit, which I believe also includes the Flywheel and it looks New as well..

Anyway, while trying to determine what Red Stator it actually was, I found countless Red Stator pictures that had a Label with 3 arrows representing placement for 3 different applications...(See Example Image Below) My Stator does not have any such label, but based on the pictures it appeared my Stator had been installed Off by one Bolt Hole or at least this is what I thought.

I decided to rotate the Stator one position clockwise, based on the pictures, and see what happened... Much to my surprise, when testing in a 55 gal drum in gear, the engine appears to be able to Rev beyond the point it would fall on its face before.

ISSUE/CONCERN:
Since re-positioning the Stator turned one bolt hole clockwise, I have now found installation instructions, on the internet (See Example Image Below), for the 398-832075A20 Kit (Assume this is the one I have) and based on these diagrams it appears the way I found it was the recommended way it should be installed. (i.e. Rotated counter clockwise by one position, back from where I have it now...)
So, if rotating the Stator Clockwise one position appears to have a positive result on the Engine's ability to Rev. beyond the point it previously stalled, do I need to rotate it back to the position the diagram indicates and then work on a timing issue or do these results somehow still indicate a bad Stator?

I wish I had history on the boat, as this might help narrow down the possibilities. Unfortunately, this is not the case and I am hoping experience from the community will help me ocheive the final objective.. "Fishing!!!"

Thank you...

The red stator kits are a pos and have always caused problems, find a good used 4 wire stator and replace it and adapter..

Just in case someone else should happen to read this post, I though I would provide the following...

Apparently the Trigger is what controls the timing, so rotating the Stator is not suppose to have an effect on timing.

I have been unable to work on the boat since my last post, but hope to work on it this weekend.

Thank you

This was Merc's attempt at a universal stator and the reason it has the different positions is to phase stator winding to the different magnet designs on different model motors/hp's.