Pontoon Boat & Deck Boat Forum

So, this weekend was a great weeekend weather wise, and saturday we had absolutely no problem and the boat ran great. Sunday was good until we started to leave and the motor would not start, IT WAS NOT THE BATTERY because the motor is on a battery by itself.
It would turn and turn and turn and never start, and then I started seeing gas in the water and I could smell it also, so I know it was flooded. What threw me off was I got it started and idle it all the way up and it ran like it was in neutral for a while and then it started to idle closer to normal but was still a little sluggish. So we pulled out and started back to the slip when the RPM dropped down to about 3000-3500.... So I was thinking well it is flooded and trying to work itself out so I will give it a little while and run it wide open and it will be fine, however after about 25 mintues of riding around at full speed it stayed the same. So I docked it and pulled the plugs to find that one was fouled pretty badly (These are champion plugs, Should I be using NGK). I cleaned up the plugs started burning the fuel and oil off of them, stuck them back into the engine and fired it up again, this time it started right up no trouble but still ran sluggish and would not idle it would cut right off if I either didnt have the throttle engaged or didnt have the Idle Adjuster all the way up. So pulled up the idle lever and had it wide open and pulled the gas hose off and let the motor run itself out of gas until there was nothing in the carbs. I am going this weekend to add new fuel ( Fuel has been in there about a month) with sea foam and change all of the plugs to NGK. Anything else you guys can think of? I think it is either bad gas or My Plugs are just not that great, this is the first season with the plugs.


So again, would not start, became flooded then ran sluggish for the next 30 minutes and never ran normal after that. One plug was fouled pretty good, cleaned them stuck them back in started right up, still ran sluggish. All I can think of is change the gas and the plugs and try again boat ran fine couple hours before (Gas has been in thre for over a month)

compression test? usually my 1st test on a 2 stroke having problems.

First guess, stuck float in the carb that is fouling the plug. If this is #2 on a 3 cylinder it can be a bad diaphragm in the fuel pump.
Did you swap the plugs around? If the fouling follows the plug ... there you go.
If you don't think this is a fuel thing (weak spark on the offending plug) you can also swap the coils, wires etc.
I have a spark checker doodad I got at an auto parts place years ago that you ground on the block or hook to the plug and the plug wire goes to the other end and you can watch the spark. It is handy to try to break the tie between weak spark and a fuel problem. Once you see what a good spark looks like it is easy to spot ta thready weak spark.

It is a 3 cylinder and it was the bottom plug, I did not switch them around I dropped my freakin plug socket in the lake, so that was the end of that. I could be totally wrong in this I just dont think it is a carb, it ran fine all weekend and ran fine that same day. I didnt start the boat originally, but they used the Idle and the Choke several times because it would not start, so once I started messing with it, it was already flooded so it didnt run after that. ( I guess that could be what caused a carb jam up was the fact that it flooded)
So since you dont think it is bad plugs or bad gas, how do I go about fixing the problems you think it is? Is there an easy way? Can I spray them with Sea Foam from the side where the spark plugs are or what?

jafo9 wrote:compression test? usually my 1st test on a 2 stroke having problems.

No Idea how to do this

We still don't know about plugs. If you have a weak spark or a bad plug it will foul for sure. That could also be as simple as a wire but real merc wires are stranded stainless steel so if the insulation is good, it is hard to have a bad one. Just be sure the outside is not wet.

BTW Old Indian trick, tie a string on any tool you want to keep

You need a compression gauge to check compression. Remove the plugs and check them one at a time with the gauge in the plug hole, cranking the engine over. The real number is not as important as them all being about the same.

Compession tester 30 bucks. take all plugs 0ut and put tester in each cylinder. crank it over and it will tell lbs. 100 over within 10 percent on all cylinders good to go

Anytime I experience a stumbling engine, I first check the fuel--Is the fuel good? Is the pickup and/or filter in the tank stopped up? Is the fuel line good? Is the fuel filter on the motor okay?

Then, I go to the plugs. Are they fouled? Everyone needs to carry a second set of plugs (@ $2.50 per plug) at all times.

Next would be to pull the spark arrestors on the carb throats, and get the motor running. After the motor is stopped, do you see any fuel dripping into the carb. throats? (On a pontoon boat, visual inspection is sometimes hard--requiring a small mirror.) If so, you may have sticking needle valves/floats.

Cleaning the carbs on a two stroke outboard engine is very easy--requiring minimal skill. There only thing you need is a spray can of carb. cleaner and quality screwdrivers. Have care in disassembly and the old gaskets can be reused. You disassemble, clean and reassemble the carb. You do need to screw down all carb. adjustment screws--noting how many turns they were at previously--so you can set'em at the same adjustments.

If the engine was still stumbling, I would ask if there is any oil in the water, and if the exhaust is badly smoking? Sometimes oil injection can have a float valve in the small tank (inside the engine cover) that won't close when full--and it will overflow through tubing into the carbs. It can be the float valve or an electronic oil module problem. This is pretty rare, but it does happen.

Good luck!

I

OK....well I cant go back until Wed. when I do I will try to get a compression tester and 3 new spark plugs just incase it is an easy fix. Someone told me before that I needed to have NGK spark plugs he heard my motor and ask me if I was running champion spark plugs, I said I am as a matter of fact. He said well your motor is going to run like shit, you need to put in NGk in there, Merc engines really like those. I just kinda blew it off but maybe he was right and maybe it is an easy fix. so change the plugs, and check the compression is what I am going to do on Wed. and I will let you know what happens I think I might try to change the fuel, if I can figure out where to put the fuel that is in it now. ( as opposed to buying a new tank of roundup)
One other thing, if I buy another bottle of Seafoam spray and I take the air box off the motor right in front of the carb. would it hurt anything or do any good to spray Seafoam directly into the carbs without taking them off and apart for cleaning?

Thanks for all your help, I will let you know what happens on Wed. if you still can think of anything else that might be an easy way to fix please let me know, thanks alot.

Think some people say not to spray the seafoam or gumout in a 2 stroke. I have done that a number of time with chain saws and did not cause a problem. Check on you tube for the seafoam video. I believe that they have one saying it is okay to directly use seafoam on 2 strokes. Heard another guy say it would cut the oil mixture which sort of make sense to. Not a mech but think it is float or diaphragm. My diaphragm we bad in the old toon and the only way I could get it to run enough to get to the ramp was by pumping the priming bulb while the wife drove. Actually might try that to see what effect it has.
doc

My diaphragm we bad in the old toon and the only way I could get it to run enough to get to the ramp was by pumping the priming bulb while the wife drove. Actually might try that to see what effect it has.

Once I got it started and running I did try that, but it was getting plenty of fuel. The priming bulb however was not hard but I dont know if it ever is while underway. It was rock solid when the engine was flooded

If the diaphragm is bad it will have reduced fuel flow but the cylinder it gets it's vacuum from will get plenty since it is squirting right in. On my 75 that was #2 but it is worth looking to see if a 50 is the same.

I would definitely go to NGK or any brand other than Champion, I've personally had nothing but trouble when I tried to use Champions plus you'll know right away if that was the problem when you try it again.

I used Champion plugs in my Merc/Mariner for 7 or 8 years (2500 hours or so) with no problem but when it got older and I started trying anything I could to get it running better so I bought NGKs. The effect was minimal.
I do think these motors just start getting tired and the effect of a dozen things is cumulative. Over the last 4-5 years I had it, I ended up throwing a stator at mine, a couple coils, wires, fuel pump, carb rebuilds and I experimented with different plugs. I could make it better but it was never new again. That is why I am planning on selling my 2002 60 4 stroke while it is still running well and let someone else have all the fun of nursing it through it's "golden years".

My 90hp merc had issues last year running poorly, starting poorly much like your talking about. Mercury had issues with the coil packs breaking down, I needed 2 coil packs.

I got the boat started and used insulated pliers and pulled the plug wire, if the motor didn't die or run worse, I knew it had an issue. In my case cylinder 1 and 2 when I pulled the wire off motor didn't change, pluged them back in and when I pulled #3 motor died. Moved the coil packs around and the cylinders changed so I knew I had bad coil packs.

I use NGK plugs and I would think that is probably what Merc recommends.