Mariner 15hp issues

Tom Russo

Tom Russo

Active member
Hello all,

1998 Mariner 15hp, 2-stroke, manual start

- Starts, idles, and runs fine most of time

- Intermittent problem becoming more frequent; after warming up (getting to spot, setting out decoys, shutting off and hunting a bit), will start and idle fine, stalls when throttling up in forward or reverse. It will go in gear and run at idle speed but stalls when throttled up. Problem is intermittent and if I run it at idle speed for a bit has throttled up and ran normally.

- Often after warming up engine will "hiccup" during idle. Seams random, every few minutes or so. Low Speed Mix adjustment does not have an effect. More often when stalling problem is occurring.

- Two years ago it would not start, no spark. Replaced Stator. Still had the "hiccup" on idle. Stalling issue was brief, perhaps once a season so I did not think much of it until now.

- Fuel/fuel line/vent not an issue. New plugs, use carbon guard/fuel stabilizer/conditioner, fog mortor etc. at end of each season. Tried Sea Foam shock treatment.

Any suggestions what I should look into, check, or test before I pull it and bring to the shop?

Thanks,

Tom
 
Tom,do you have the shift control in the tiller handle on that motor.....if so you can't race it out of gear.....I hate mine.....a Mariner guy told me that on that model the carb has to be 100 percent ...some times you get some corrosion in the passage ways and it will cause it to stall ....
 
Tom-you mentioned that after you replaced the stator you "still had the hiccup" but was more frequent, so you did have the problem before the stator was replaced? If that is the case, I think the carb is the first place I would look, as loss of power under a load is usually some type of fuel restriction. I think the carb should be a pretty simple job. I would get a manual on your motor if you don't have one. I found an electronic one(factory manual) for one of my motors for about $7, it is a pdf and is priceless. You are going to have to test it under a load. I think I would also check the wiring in the handle which should be integrated with the kill switch, you could possibly get some vibration while the engine is under a load and it could be shorting if you have some insulation rubbed off. I have a Merc 9.8 from '97, not sure if they were the same by then or not, but I think they might be. Good luck and keep us informed.
 
Just a FYI you may have a Yamaha motor, some of the early smaller Mariners were Yamahas and the bigger ones were Mercs. Not maybe any help but interesting. Stumbling on acceleration, I would look at idle fuel mix because when you open the throttle you are only letting more air to the engine and maybe not enough fuel. Clogged passage = lean mix. Certainly could be something else but that is where I would look.
 
Tom-you mentioned that after you replaced the stator you "still had the hiccup" but was more frequent, so you did have the problem before the stator was replaced? I don't recall any hiccup/idle issues before changing the stator. Just before the opener a couple of seasons ago it did not have a spark, after changing the stator it started and ran fine. I think the hiccup was sometime after after the stator change and only after the engine was warm. I have the service manual and will play with the mix screw and take a close look at the wiring tomorrow. Tom
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Tom I had a 9.9 Merc that did exact same thing. I fought that motor for a long time trying to figure out what was wrong. Rebuilt the carb etc. Finally I found the problem, a pin hole leak in the fuel line. When you went to throttle up it would suck air threw the pinhole. You might want to replace the fuel line in the motor and see if your problem goes away. Replace those nasty cheap factory clamps while your at it.
 
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