boat motor problems, I need help or guidance

[mike bell]

alright first off let me state that I have no mechanical smarts or knowledge. I know but Ive never had anything worth keeping and working on.


Its a 92 (I think) yamaha 25 hp on a 15 Fisher. (Auto oiler, no mix) Its only been used a few times a year since 1994. It was my dad's and he has passed away and now I have the boat which wasnt running right last time we used it two years ago. So Im trying to fix it up for my family to use and I thought having the carbs rebuilt would solve the problem. As far as I know, he never had any work done to it ever...

So I sent the boat off a few weeks ago and had the carbs rebuilt. So I go to the lake this weekend and its still not running right. Acting up about the same way. Bogging down in the throttle and cutting off.

I played around with it screwing the jets in and out, making sure they were the same turns and tried them at different positions. nothing worked so I settled on 5 turns from all the way in on both carbs.

It would start up and idle as long as I gave it a flip of the electric choke switch. When I got into gear and into the throttle, it would bog down and shut off. I checked the fuel lines and everything was getting gas. I think. After sitting there looking at it and scratching my head Sunday between the rain storms.....I started it with a flip of the choke switch and quickly went to the motor and pulled the manual choke knob out and it ran a little better. So I jump in and try to take off and it starts bogging down again. So I flip the electric choke switch and it revs up some, so I flip it again as I give it more throttle and it takes off more, I go full throttle and it takes off across the lake like a brand new motor! ye haw I fixed it....wrong. I have to flip the choke switch every time I start to go into the throttle. When I throttle down...it bogs down the same way unless I flip the choke switch. But it idles in gear fine.....

Choke means, not enough gas right?

Im thinking it has got junk in the carb again from the gas tank...(it was empty) I put high octane gas in it but it was the ethanol gas.

I bought an inline filter im going to put on the line from the tank before it goes into the motor. Should I change the plugs and the oil out?

Also, Ive heard of changing the oil in the lower unit? I dont think its ever been done before? Is that something I can do?

 

[CAL]

What you are telling me is the engine is starving for gas.Either the carb.is still stopped up or the gas line is not delivering the gas.I think the carb.is stopped up still.Carbs.are hard to clean up at times.I have found running tiny leader wire everywhere I can to make sure the lines are clear in the carb.itself.I think you will find some kind of restriction in the high speed jet by it bogging down when you open it up.Might be the float level is set too low.I would take it back to whoever worked on it for a do it over at their expense since they just worked on it.

 

[Laneybird]

You have changed the plugs, right?

 

[Twenty five ought six]

I don't know specifically about Yamaha, but on any other engine, 5 turns out of jet is about 4 too many.

I tend to agree with Cal, a clogged jet. Take it back.

BUT, I also think of addressing the easy things first. See if you can locate another fuel line known to be good, and swap it out.

BtW, you have vented the gas can cap haven't you?

BTW, as I said, I'm not familiar with Yamaha, but you keep referring to "carbs' -- does this 25 have two carburetors?

 

[win270wsm]

go to bbc.com and ask one of the experts in the yamaha boards.
those guys know their stuff!

 

[mike bell]

One turn on the jets and it would not run at all. four or five seemed to be in the middle....I think. And yes it has two carbs on this thing. I may look into some drawings cause I thought it only had one jet on each carb.

I didnt changed the plugs but I did take them out and clean them off. They looked a little fouled (more wet) but not to bad. I took them out when it wasnt running at all after I was cranking it. After I put them back in and turned the jetts, I got it running.

Oh and yes, venting the gas tank was the first thing I did. I learned that about five years ago at the same place and holiday weekend....

 

[kikkup]

Factory settings should be 3 1/4 turns on the carbs and yes it does only have one jet.... the screw you are trying to adjust is the air screw... PM me Maybe I can help