Need Guideance. 2001 Merc 50 ELPTO

[Sprayer]

In July I purchased a 2001 Mercury Outboard 50 ELPTO (SN 0T31313854) for $3000.00 Motor was claimed to be freshly tuned up/serviced and water ready fresh from a trade. Once installed It would not run faster than 13 mph by GPS ran up to 20 MPH for first 20-40 seconds then bogs down at WOT and slows to 12mph. I squeezed the primer ball hard, hit the choke no improvements with WOT still. Went back to Marine business I purchased it from and they said Sorry "sold as is". Its Ok to lie. Filed a complaint with the attorney general consumer complaint division. My word against theirs so it seems.

My boat is a 1994 16 foot G3 river john boat. Like a bass-tracker just thicker aluminum. Rated for a 50 HP.

So took motor cover off and began trouble shooting. Found Yellow wires to stator burnt and melted that was covered with electrical tape to hide it. Found Voltage regulator shorted. Stator tested slightly below of resistance spec. Replaced Stator and Trigger ( since I was there) with new CDI parts. Replaced bullet connectors from the connecting parts listed above. Replaced Voltage regulator with New OEM Mercury part. Tested on water problem still exists.

Replaced Fuel lines with 3/8 Ethanol rated from auto parts store starting at tank all the way up to fuel filter and a new specified fuel filter as old one was a lawnmower style. Rebuilt manual fuel pump. Looked ok inside. Rebuilt all three Carbs and cleaned all orifices to ensure they are clear with Carb cleaner spraying through. Installed new idle set screws and springs and new inlet needle valves verified operation before assembly. All new gaskets. I inspected the Reeds and they looked good as in no bent or missing pedals. Returned Low idle screws to 1.5 turns as was before. I tried adjusting +- 1/4 no improvement. Tested on water problem still exists. Did make it to 28 MPH then bogs down within 30 seconds and dies. Starts and wont go past 15 MPH. No duel leaks even when squeezing primer ball hard.

I used a spark tester and have spark on all three plugs and look similar while running. I have a clean 3 gallon fuel tank with fresh 87 "ethanol free" fuel purchased this week. No chance of water in fuel. Only thing left are the CDM modules. I am however wondering about the Timing and tuning of the carbs Etc before I shotgun the CDM's. It does run rough at idle but feel its typical of a Merc 2 stroke. It will idle on hose for several minutes then want to die. Like its loading up with fuel. At lake today on trailer it will oscillate from 1500rpm to 3500RPM while at WOT. Compression is 115-120 on all three.

Why I have done all this shotgunning? I am an electrician and mechanic so felt capable of fixing. I am a 100% disabled Gulf War Veteran so my resources are limited but have lots of time tools and a shop manual. I want to keep this forever so don't mind rebuilding it to last and not strand me on the lake. But now am out of patience. What am i missing before I take it to a Boat repair shop.

Any help is appreciated.
Thanks

 

[CaptnKingfisher]

Compression numbers don't lie, but spark and fuel do. Read the plugs for clues about your spark or fuel problem. You could have weak or intermittent spark issues for example a weak coil or bad plug lead will be made obvious if one of the cylinders has a black plug and the other cylinders look normal. Or if all the plugs are black that could indicate a weak spark from your new stator or bad idle mix. Coils are easy to bench test with a multimeter for resistance on both circuits. Plug leads should be tested for resistance as well. When you put the plug leads back on, use dielectric grease. While you have the plugs out I would also verify you've got the right plugs for the engine and they are gapped correctly. If the plugs all look the same and have that nice brown color to em then we can move on to fuel issues.

I like to carry a handy little can of fresh fuel that Walmart sells so I can pour it directly into the carb while the engine is running to see if that fixes my issue with fuel delivery. If it makes your engine run better, then might need to rebuild the fuel pump again. If there's no change in bad performance and you have strong spark and good compression then it tells me your problem is in the carburetor. Idk of this tip can be used on your engine as you said you have three carbs so you'll hafta play around and see if this is a helpful diagnostic tool or not.

By the way to set idle mix correctly you need a good tachometer unless you've got the "ear" for it. I don't and not many people do. Use a tachometer, turn screw clockwise until rpms begin to drop due to a lean condition. Then turn screw counterclockwise slowly. Rpms will begin to climb. Continue turning counterclockwise until rpms begin to drop again due to a too rich condition. Now you've got an idea of your range. Turn screw clockwise in small increments adjusting for maximum rpm and engine smoothness. After you've done this correctly you may need to change your idle speed screw to service manual recommendation.

 

[Sprayer]

Compression numbers don't lie, but spark and fuel do. Read the plugs for clues about your spark or fuel problem. You could have weak or intermittent spark issues for example a weak coil or bad plug lead will be made obvious if one of the cylinders has a black plug and the other cylinders look normal. Or if all the plugs are black that could indicate a weak spark from your new stator or bad idle mix. Coils are easy to bench test with a multimeter for resistance on both circuits. Plug leads should be tested for resistance as well. When you put the plug leads back on, use dielectric grease. While you have the plugs out I would also verify you've got the right plugs for the engine and they are gapped correctly. If the plugs all look the same and have that nice brown color to em then we can move on to fuel issues.

I like to carry a handy little can of fresh fuel that Walmart sells so I can pour it directly into the carb while the engine is running to see if that fixes my issue with fuel delivery. If it makes your engine run better, then might need to rebuild the fuel pump again. If there's no change in bad performance and you have strong spark and good compression then it tells me your problem is in the carburetor. Idk of this tip can be used on your engine as you said you have three carbs so you'll hafta play around and see if this is a helpful diagnostic tool or not.

By the way to set idle mix correctly you need a good tachometer unless you've got the "ear" for it. I don't and not many people do. Use a tachometer, turn screw clockwise until rpms begin to drop due to a lean condition. Then turn screw counterclockwise slowly. Rpms will begin to climb. Continue turning counterclockwise until rpms begin to drop again due to a too rich condition. Now you've got an idea of your range. Turn screw clockwise in small increments adjusting for maximum rpm and engine smoothness. After you've done this correctly you may need to change your idle speed screw to service manual recommendation.

Thanks for the response. I do have a Merc tachometer and have the idle adjusted to 900 rpm as manual states. I did try adjusting the idle screws back 1/4 and leaned it out and past 1/4 and really didn't notice an improvement so returned to the 1.5 turns from bottom starting point.

Today's in water test I force squeezed the primer bulb while under power and did not help the engine run that should eliminate pump I felt like it made the motor die but its not running correctly so dismissed the notion. Pushing in choke had same result but Don't think the choke is working as I cant hear it.

I tested the 3 CDM's last night and all 3 diode check and ohm out per manual. D to B pass diode test A to D pass diode test A to C 1095 Ohms A to Boot 1050 Ohms all within spec of manual.

I haven't checked the plugs for black or for correct part. Will check that today. Not sure if the rev limiter can cause this problem. Cant find how to test in the manual or bypass it. Without load I can get engine past 5000 RPM momentarily.

Checked plugs just now all kinda cruddy bottom one was pretty black. Correct Part (NGK# BP8H-N-10).