'99 Tracker Bigfoot 60 HP 3 cyl 2 stroke losing power / misfiring at high rpms

[gydatree]

Hey guys, Ive been working with this motor and before I go replacing things and/or tearing things down I figured I see if u guys had any suggestions.

So the first couple of times I took it out it had been sitting for a while, doesnt get much use. However, though it did have a small misfire at times, seemed to be one cylinder losing power, but it would keep going and once i cleaned up the carbs a little it seemed to be fine the next couple trips.

So, went out a couple days ago, put a new filter on, and I think there may have been a good amount of water in the tank from some storms we had that i didnt notice til later. it rode nice out of the cove, but once i got to the big water it started misfiring and eventually lost all power. i could not get it to fire at all and got towed in. while waiting for the tow i pumped out what seemed to be most of the water out of the tank, but could never get it to fire.

So, I went out there today and drained all 3 carbs and put new plugs in. they were the ngk plugs and it had the champion ones in it originally, though they looked the same. I also took a fuel sample coming through the line, and there was a very tiny bit of water in the very bottom. So, it fired right up and idled smooth and strong, i pulled away from the dock and rode low speeds out just fine. took it up to maybe 4000 rpms for a quick second before i beached on a close island, still just fine. pulled off of the island, and started out to the big water with no issues. Not long after I hit the big water it started missing and losing power like it did before, and i was able to keep it at a low speed back to the island. i pulled the plugs and cleaned them, seemed to have a bit of oil on them. it didnt want to idle smooth anymore, had to keep it rev'd a little to keep it going, and though it did get me back to the dock if i pushed it over maybe 2500 rpms it acted up misfiring and losing power. I also noticed that, even though fuel was coming through the line just fine, there was a visible pinch on it under the oil reservoir.

So it seems like it could be a number of things:

Voltage Regulator and/or stator?

compressiom issue at that temp/rpm?

rich oil mixture?

Dirty piston heads?

bad gas?

Any suggestions would be greatly appreciated!

 

[Texasmark]

Get rid of the water, all of it. Get fresh 87 octane fuel from a reliable source......gas station with a lot of business is a good source. NGK is the preferred Merc plug. Do a complete carb cleaning....get kits....iboats sells them.....go to top of page: look at Boat parts and accessories. Come back with results.

 

[gydatree]

No Title

Thanks for the advice Texasmark! I went and pulled and cleaned the tank yesterday, doing the carbs today.

I wanted to ask before I did all that how the plug that came off of it looked i.e. rich/lean or excessive carbon. Im pretty handy at doing this kind of work but it is fairly new and I wouldnt know exactly how the plug is supposed to look, and I am trying to figire out if I should do a de carb with sea foam or even pull the head plate and clean the piston heads and put a new gasket on.

Here are pics of the plugs that were put on right before summer this year, and not used all that much.

Just wondering how these completely lost spark and then fresh plugs got it going strong but once it semmed to be warmed up started having the misfire and power loss. When it happened the first time, I kept trying to give it gas thinking if it was the carbs it may push through, but thats when it completely died. With the new plugs, I just kept it at low speed when it started misfiring and losing power, and was able to cruise into the dock. The new plugs were pretty wet with what i might think was a rich mix, but wiped right off and looked new.

Anyway, just wanted to get some advice on that, as I am working on a couple other 2 strokers and may consider the de carb or head cleaning for them also.

 

[Texasmark]

Time for new ones. Tan ceramic is the preferred temp and expect to pull it out wet, not carboned up like that one however, as you stop the engine by killing the spark so it takes a few rpms for the engine to stop rotating, all the while it's sucking in fuel mix.

 

[gydatree]

Allright, so I did the seafoam decarb, cleaned the fuel tank and replaced plugs. Turns out the cowl top latch was damaging the bottom spark plug wire, so I replaced it also.

The Seafoam mix we did ended up being about a gallon and a half with the 16 ounce bottle, so I actually did 7 15 minute runs with 15 minute breaks and still had a tiny bit of mix left, and small amounts of smoke still. Once I hooked it back up to non ethanol 90 octane fuel, it had to be chocked to start if cold, but runs great from start to finish, and doesnt burn all that much gas.

However, it did do the skip on me twice very briefly throughout the day. Both times, after shutting down and checking the wires, then going again it would eventually get back on full power and run great. I never did rebuild the carbs, but they were done about 6 months ago. Im hoping theres not still an electrical/spark issue and there was somethig working its way through the carbs.

I will take her for a spin today or tomorrow and report if its still giving me a skip or not.

 

[Texasmark]

The decarb will clean up the carbs too, just may take some time if you have some heavy varnish. On a '99 your little "skip" could be a piece of (black engine internal) fuel line in the bowl of one of the carbs. Floating around it can intermittently clog the high speed jet which, if like my 90 is buried in the bottom of the bowl.......how do I know that??????? Time for new plumbing in the engine and while your at it, get a new fuel line and bulb. At 10 years I had my tank to engine fuel line flaking internally and the flakes clogged the fuel system.