Motor problem

[canon]

I have an '91 Evinrude 40 horse 2 stroke motor. Last year I was fishing on the croix, went a longer than usual distance and started having motor problems. At full speed, the motor would bog down and then abruptly stop, when I would try to restart it, the motor would turn over slowly, like the sound of a drained battery, although when I waited a minute or so, it started right up. I thought maybe I had an overheating problem. I always have had good stream of water coming out. I checked the plugs and found one plug was fouled out. I changed the plugs and it sounded good. However, now at top speed, the motor misses evenly like every half second or so, when it is not at full speed, it runs fine. Could this be a coil problem? fuel problem? Please any advice would be nice.

[marine_man]

I would start with running the motor on the hose, and when it starts missing, pull one spark plug cap off. If there's no change in the way the motor runs, the cylinder you pulled the plug cap off is the one with the issue. If it's not move to the second cylinder.

Once you've identified the cylinder I'd see if you have good spark, and try to isolate if it's a spark problem or a fuel problem.

I'd also think about a compression test, just to validate that there's no problems there, but the 40 hp OMC motors aren't known for cylinder issues, so I think you'll be all right.

marine_man

[Charley]

Could there be water in the gas? I know the starting issue could be somrthing else.

[canon]

I will look into that, the thing I noticed when I took out the spark plug that was fouled, it appeared to be a lot of oil/gas in the cylinder. The spark plug looked like it was in pretty bad shape. I am hoping the fix is not too costly.

[wastewaterguru]

It almost sounds like the timing issue I was having last year. Those symptoms could be from a lot of things including a failing CDI box since they usually act up more at higher engine temperatures.

Check the following post for the issues I had....

http://www.fishingminnesota.com/forum/ubbthreads.php/topics/1541728/1

[VMS]

Hiya,

I might start with a good can of sea-foam directly into the engine. Problem with using it, though is no easy way to get it in the carb.

Mercury makes a product called Powertune that is pressurized. Basically the same stuff, but it will decarbonize the whole system...cylinders and all. Get the motor warm after taking off the silencing shroud over the carbs. At hight idle, start spraying powertune directly into the carb throats...the motor will bog down a bit but not die. After about 1/3 of the can is used doing that, shut the motor down and spray more into the carbs. Let sit for about 30 minutes, then run the [PoorWordUsage] out of the engine to get all the gunk out.

Replace your plugs, and see how things run then....

One thing that does happen over time as well is the plug wires will lose their conductivity due to age. your motor is almost 20 years old now, and if they have never been replaced, there could be more resistance in the wires, thus the reduced spark.

Timing issues can happen with that, and if you have access to a timing light, you can at least test idle timing. I had to do that with my 99 johnson 50hp, and that thing purred like a kitten after that. Started with barely a turn of the key.

Steve

[canon]

Thanks for the reply's, I welcome any ideas. I just can't get one symptom figured out, why when the motor bogged down and just quit at high speeds, why did it not start right away???? It sounded like a dead battery sound but it wasn't, you let it set for 1 minute or so and it fires right up like nothing is wrong, it makes me think something is heating up? I wonder if it is a coil going bad, can they heat up then drag when trying to start? I feel it is a fixable problem, I am a little scared to take it in and spend $ on narrowing it down, it seems like it should be a simple fix. Like I said, I put new plugs in and it runs great but misses at high speed. I didn't take it on the water for resistance, I used the water muffs in my driveway, so maybe it wasn't a good test to see if anything is still heating up.

[marine_man]

You really need to isolate which cylinder is giving you the problem - see my post above.

Until you have those things sorted out it could be a variety of things.

marine_man

[gregg52]

i had an 89 evinrude coules yrs older

but mine acted similiar to that it was a cylinder and ill bet its the one you think was fouled

i had my 89 rebuilt once and the told it would be good for bout 3yrs and thats how long it went

the good thing was the first time it went it went

it didnt nickle dime me to death after bout 18 yrs of being

very relialbe !