1994 Yamaha 115, bogging down problem

[keiperrc]

Hey gang. Any ideas on this ?<br />I just got this boat, ran great last week, I put gas in it today, pre-mix, but I used the Pennzoil Synthetic, I could no get to the dealer to buy Yamalube last week. <br />Anyway, to the symptoms, running along fine, then the motor just bogs, I back off the throttle, and it wants to stall, wait a few seconds, then it picks up power again, runs fine for a couple minutes, then does it again, sometims stalls , sometimes it doesn't, but it just falls on it's face, over and over, when it does stall, it take a long time to get it to fire again. At one point it ran great for 5-10 minutes, other times, 30 seconds. <br />I get it home, and it fires right up, and revs fine, pull the plugs and they look a little wet. Not sure if they should or not, the plugs are new, only ran them once before, last Wed. and it ran perfect all day. <br />Ok, so, any ideas, maybe carbs flooding the plugs ? ( I know they were cleaned a couple years ago, not sure exactly when ) , maybe it's bad gas ? doesn't like the oil ? <br />It's odd because it runs perfect for a few, then just dies out, and then will run great again in a few seconds.<br />It almost feels like it's flooding and drowning the plugs, then once it burns the fuel off, it will get up and run again. <br />thanks much for any ideas you could provide.

 

[keiperrc]

Re: 1994 Yamaha 115, bogging down problem

Well, I'm amazed , I got not suggestions on this. <br />I did however take off the fuel/water seperator fuel filter, dumped it out and got some water bubbles, and about 1/8, to 1/4 inch of brown crud in the bottom of the glass.. So I bought a new filter, filled it half full of sea foam, installed it, and ran the motor, it started right up, smoked for a few, and ran fine, and revved up fine, but not under load.. <br />Anybody think this could have been my problem with the engine dying out intermittently ? Or should I keep looking ? <br /><br />thanks from the noob..

 

[rodbolt]

Re: 1994 Yamaha 115, bogging down problem

myself I would test the compression and the spark. then I would replace the fuel pump and rebuild the carbs as the condition of them is unknown, then I would test the alarm system to see if it actually works or not. its all a process of elimination. to test the ign system at speed will require some expensive equipment. luckily yamaha electricals rarely fail but they do. so elimintae the fuel and such before jumping on ign. a fuel vacum gauge is indespensible for finding restrictions. start at the engine filter. vacum should be less than 4" Hg at wot. if its more than start moving towards the tank until you find the restriction.

 

[keiperrc]

Re: 1994 Yamaha 115, bogging down problem

Wow, kind of what I thought, this could be a hard one to pinpoint. I think the compression is fine, it runs great when it's burning fuel, just cuts in between, last week, it ran great all day, no problems at all. started doing this after I put more gas in. <br />I am pretty new to this, so not sure I know where to begin checking all this stuff, but I know a little. I did notice at idle, the primer seemed to soften up a little, not sure if that's normal, or might be pointing to a fuel pump.. I have some idea of the maint. history of it, since I bought it from someone I know who has had it for 4 or 5 years, and taken good care of it. All the fuel lines were replaced recently, and the fuel/water filter added, carbs rebuilt 2 or 3 years ago, and it was run pretty regularly since. <br /><br />thanks for the info rodbolt.. nice to have some experts to talk to so I can at least have some idea what's going on.