Frustrated with 1998 Tracker Force 40HP

I recently bought a used Tracker Pro 17 with a '98 Tracker Force (by mercury) 40HP. I've been chasing my tail trying to figure out why it misfires right at or above 4,000 RPMS. 127PSI on both cylinders. I've performed a Sync & Link, set cranking timing, replaced adapter plate gaskets due to exhaust leak under cowl, w/p impeller, foot oil, battery, propeller, starter solenoid, throttle & shift cables, both CDM modules with wires, spark plugs, reed petals/gaskets, fuel pump diaphrams/gaskets, all fuel lines, primer bulb, fuel filter, priming system hoses from carb to primer solenoid, recirculation/drain hoses from transfer covers to fuel pump, removed transfer covers and cleaned/verified flow through passages & elbows, removed recirculation/drain check valves & cleaned/verified flow through them. The prime solenoid seems to function correctly and will bog motor if key is pushed in while cruising. I've made sure my tank vent was open, and even ran it on a brand new portable tank with fresh gas & 50:1 mix of Mercury Premium Plus Synthetic Blend with Shell 87 octane. I've ran Mercury Quickleen through the tank a few times already. I peformed a decarbonization with Mercury Power Tune and cleaned the spark plugs afterwards. I removed the carb and disassembled, it was beautiful inside....no varnish/gunk at all, float looked to be set correctly, jets & passages blew cleaner through them easily. I peeked under the bottom of the flywheel to see if the stator had any melted gunk coming out or any cracked/broken magnets...none. I looked at the voltage regulator box to see if it had any melting or cracking...none. The motor has a definite erratic misfire at 4000+ RPMS, I can get it up to almost 5,000 but misfire is still felt. The previous owner had installed a tell-tale and the last time out I folded the hose over and zip-tied it shut to see if loss of water pressure had been causing a hot condition...no difference. The only odd thing I noticed a few weeks ago was I saw the volt meter go up to like 16 or 18V after startup, but within 30 seconds it dropped to 14V which is where it always runs....not sure if gauge was acting up, if this is normal, or if the regulator is messing up. I understand a bad regulator can fry a stator. I've HEARD the "black stators" mess up frequently and the "red stators" are tough. Looking at mine from under the flywheel, it appears black, not sure about the top side of it. I was an auto mechanic for 13+ years, but left the field in March, so I'm pretty good mechanically, but I'm getting a rough crash course in 2-stroke 101 right now! I work for Tracker Boats in the parts dept. Our techs are great guys, but aren't exactly seasoned pro's and are as stumped as me (if not worse). We are a Mercury dealer, so I have access to parts diagrams & service manuals. Any help/input is appreciated.

Re: Frustrated with 1998 Tracker Force 40HP

If you haven't already done so, try a set of NGK BUZHW or BUHW surface gap plugs.

Check the wires that come out from underneath the stator to make sure they are not rubbing against the flywheel or the engine block and exposed the wires and shorting out to ground when you move the throttle back and forth. Also check the magnets under the flywheel to see if any are missing or broken.

Check the ground wire that goes from the CDM mounting plate to the engine block. Make sure it's making good contact at both ends. Somewhere I remember reading that there was a Tech bulletin to add an additional ground wire between the two (mounting plate and block). Not 100% sure about that though. Make sure the "bullet" connectors Between the stator and CDM's and voltage regulator are making good contact. The bullet connectors on the yellow stator wires going to the regulator are sometimes burnt looking like they were overheated. Make sure the body of voltage regulator itself is making good contact with the mounting plate. This is the ground reference for the reg.

Check the stator with an OHM meter. You should see 500-700 ohms between the Green/White and White/Green wires coming from the stator.

Try running the motor without the voltage regulator by disconnecting the two yellow stator wires (Tape the ends off if necessary to prevent them from touching anything) and see if that makes any difference.

Re: Frustrated with 1998 Tracker Force 40HP

I currently have Champion L76V "gapless" plugs in it. The parts manual calls for L76V or QL76V, both are "gapless". When I first bought it, it had gapless NGK's in it...not sure of the part numbers but I saved them, so I can look after work today. That part # sounds kind of familiar though...are they "gapless"? I also ran all fuel out of my inboard tank so that I can try 93 octane on next fill up just to see if it helps at all. The manual says "87 minimum", so that is kind of open to interpretation...also when the manual was printed they didn't have E10 to worry about.

Re: Frustrated with 1998 Tracker Force 40HP

Yes the NGK BUHW are gapless just like the L76V. L76V Champion should work fine too. I don't think you'll see any advantage in running 93 octane vs 87, but it's more personal preference. Go through the things that I mentioned above, especially the stator resistance readings and grounds.

Re: Frustrated with 1998 Tracker Force 40HP

You will need to remove the flywheel to check the magnets. Make sure all are present and in tight fit under flywheel. If the stater looks black,or like its been overheating then this could be your problem. Check the ohms with proper tester gage as stated in previous thread. You will also want to check the trigger for any broken, or shorting wires coming right out of the trigger housing by gently moving them while motor is running. Careful of spinning flywheel though. Check all wire connections at the butt connectors for clean tight fit and you may need to give them a little wiggle to while motor is running. The small wires have been known to break right under insulation. Your problems sound electrical related and hopefully can be an easy fix.

Re: Frustrated with 1998 Tracker Force 40HP

I printed the section of the service manual on testing the stator and ignition components. My biggest concern is that it only misfires with a load on it...runs good on the hose. I'm just worried I may get false readings at the house with no load.