OT: 9.9 Yamaha 4stroke Outboard Woes

Ok I'm pretty good with little motors, but I am pulling my hair out now. I have a ratty pontoon boat and 9.9 Yamaha 4stroke that I got free with my house (yep, it was worth every penny) a couple years ago. I have taken it to two different repair places over the last two years (fortunately I also got a free trailer) and they have proclaimed it cured after various cleanings and fixings. HOWEVER, I get it back in the water yesterday and it runs then dies, runs then dies (just after a few seconds). It will idle, but apply power and it dies, and it does not produce any power. It seems like an electrical problem to me but I don't know how it would act if the CDI unit was out (I'm more of a points and condenser kinda guy).

Things that HAVE for sure been done: New gas, new plugs, carb cleaned.

Meanwhile, I have a really nice dock ornament with chairs to sit in.

Any ideas or similar experiences would be helpful.

I did hear that the best way to cure the problems with Yamaha outboards is to replace them with a Johnson....

Thanks!

sj

Sounds like it could be a head gasket? Or weak valve spring? My experience with CDI is when they fail there is no warning and the engine will not run at all.

And there is no such thing as a free boat....

Good Luck
Larry

Thanks, Larry. This engine is about 10 years old and probably has only about 100 hours on it.

It really seems intermittent - electrical to me. When it is running right, it runs GREAT, so that is why I was not thinking head/valves.

I kind of thought it might be the bystarter also.

sj

Sounds like the fuel line is sucking air.

I have tried two fuel lines and two fuel tanks (the boat has a built in tank, and I am now running on an external). The fuel connecting fittings are not as stout as they were in the old days, and I have jacked with that quit a bit. The pump ball on the fuel line remains firm (so I don't think air is getting introduced) but it certainly is something to look at again. Of course, the repair guys just run it on their gas with their connector I suspect.

I will check that out again - thanks!

sj

So they only cleaned the carb?

Every gas power tool I own, that runs about as much as your boat, has needed the carb re-built since the ethanol has been eating them.

I just assumed that had been done.

cafi

Fuel filter? Clear hose and separate gas can to see that it is flowing worked as a troubleshooting tool for me.

Again, thanks for the good ideas. I'm with you on suspecting fuel flow. I actually suspect the fuel connector on the engine may be part of the problem.

sj

Did you check the internal fuel line for cracks or loose fittings.

My engine did the same thing -- idle fine but cut out under power -- and it was because the fuel line was sucking air from the cheap hose crimps they use now-a-days.

You would think the guys who fixed/tested it would have come across the inside lines being bad. They are all very pliable - inside, the engine looks new, but I will double check for sure!

sj

I use 100LL in everything, lawn mowers, chain saw, leaf blower, generator and outboard motor. They always start even after spending months unused. The extra cost for a years amount of 100LL is insignificant when compared to the reliability.

And I've had 100LL goof up more than one little engine because of the high lead content so I quit doing that. I do like the fact that you don't have to put stabil in it.

sj

Cafi is on the right track here. As a boat dealer we have seen lots of problems caused by ethanol in the gas. Google "ethanol in boat gas and read all about it. The fix is to use a product called Star tron in the fuel. It has eleminated all of our ethanol related problems. This product or one like it should be used in any small engine that sits around most of the time. Try adding some to the gas and running it for a while. If that does not fix it you will have to have the carb rebuilt again.

Jim

Jim, don't tell her she is on the right track, I'll never hear the end of it! :lol:

Just talked to the "boat guy", of course, he can't get out and look at it until after the 4th, but he does not think it is fuel related since he just had the thing running for one hour in his shop on some gadget I can't remember the name of. He said sometimes you just have to see how it acts on the water.

I doubt ethanol could be a factor in 10 minutes of running, plus I usually use premium which does not have ethanol in it here (or says it does not).

sj

New squeeze pump ball.

5.00 at wally world.

It's a brand new gas line with new ball and new connectors.

and it was NOT bought a Walmart so I know it will last more than a couple days...

sj

Try one thing for me Steve. Remove the hood and try running it without the hood. If it runs ok that way get back to me. I'll tell you whats wrong. Thats the way the mechanic runs it in the tank. Dave

steve said:

Ok I'm pretty good with little motors, but I am pulling my hair out now. I have a ratty pontoon boat and 9.9 Yamaha 4stroke that I got free with my house (yep, it was worth every penny) a couple years ago. I have taken it to two different repair places over the last two years (fortunately I also got a free trailer) and they have proclaimed it cured after various cleanings and fixings. HOWEVER, I get it back in the water yesterday and it runs then dies, runs then dies (just after a few seconds). It will idle, but apply power and it dies, and it does not produce any power. It seems like an electrical problem to me but I don't know how it would act if the CDI unit was out (I'm more of a points and condenser kinda guy).

Things that HAVE for sure been done: New gas, new plugs, carb cleaned.

Meanwhile, I have a really nice dock ornament with chairs to sit in.

Any ideas or similar experiences would be helpful.

I did hear that the best way to cure the problems with Yamaha outboards is to replace them with a Johnson....

Thanks!

sj

Click to expand...

Yamaha

Steve, this sounds identical to the problem I had on my 2004 Yamaha 2.5 hp 4 stroke outboard. I suspected fuel flow issues-something in the jets - I had the carb on and off and apart more times than I could count and no luck. Also, there is an inline fuel filter-check that. I put in a new plug, still nothing. Finally brought it to the Yam dealer. After pulling his hair out for hours they could not fix it. Then they replaced the whole carb with one off a new motor, and walla, it ran perfect. $380 for the carb and install for a motor I paid $800 for new. Now what in the world was bad in the old carb that they couldn't just replace the part, I don't know. I have the old carb, and some day may look closer at it. Hopefully your problem is cheaper. All the gaskets, o rings, jets etc look perfect in the old one. If Yamaha sells a carb rebuild kit, I would take a shot at that first. Now days it could be you have to buy the whole carb though. Russ

Thanks. I figure a new 9.9 (lake limit) is probably $3500 so $350 for a carb would not be all bad... Perchance did the new carb come with a new bystarter? The little gadget that acts as an automatic / electric choke?

sj

check to make sure the arrows on the primer bulb are pointing in the direction you want fuel to go. I had to"fix" a relatives boat a couple weeks
ago was acting the same way. I have found the 4 stroke Yams to be bullet proof, especially the 9.9. Is yours the high thrust version? The would swing about a 12 inch prop.

Jim

Jim,

I did check that... not my first rodeo making that mistake

sj

There are more fuel lines/connections inside the motor... if even one goes bad you are


Start the motor, then take carb cleaner and spray it on the lines and connections, if you get a change in rpms, you have a leak where you just sprayed.

If the Carb has one little, and I mean microscopic bit of lint in a jet, (read varnish from not running it enough), it will do what you are talking about also.

Take the carb off, tear it down as much as you can, put all metal parts in a small container with mineral spirits, place on a bench next to a bench grinder- now turn the bench grinder on (anything that makes vibrations in the mineral spirits). Come back the next morning and reassemble.

(This is a trick proported on Supercub.org a few years ago, and it works) :lol: 8)

Worth doing to save $350

Also, check that your gas can is vented.

Gas can vented....

There are a LOT of fuel lines in there.

I like the carb cleaner idea.

BTW, the carb for that engine is $475... ouch.

Steve I used to be a Honda/Johnson dealer. Seldom does throwing parts at a troubleshooting situation solve the problem. You need to seperate this into a fuel/ignition problem first. You are lucky in that it sounds like the engine has a radical problem as opposed to a "nuance" problem like the thread where the guy is having a oil temperature problem with his SC. I think Harbor Freight has an inline ignition testor. It has a neon light loosly coupled to the spark plug wire. Rig a couple of those inline with your spark plugs and see if the spark goes away with the problem. One caveat on that, if the plug is fouling out from rich fuel the tester can lie sometimes but it's a start. Next thing to do is get the engine running and then set it where it dies or runs badly and shut it of quickly and pull the plugs. Are they black and sooty (weak spark or air/fuel problem)? Wet (probably spark problem (did the lights go out on the inline testors?)? Dry definently fuel/air delivery (clogged fuel system (likely), compression loss for some reason(least likely))? Large difference between two plugs colors (swap ignition system components between cylinders if you can) DO a compression test- wide open throttle while turning over with starter. Should be aty least 150#. Test it hot too. I am not familiar with the Yamaha outboard but if similiar to the engines I used to work on the ignition systems were seperate between the two cylinders so highly unlikely that both would go intermittent at the same time. The plugs tell all on that. Hope these ideas help get to the bottom of this. Dave


quote="steve"]Thanks. I figure a new 9.9 (lake limit) is probably $3500 so $350 for a carb would not be all bad... Perchance did the new carb come with a new bystarter? The little gadget that acts as an automatic / electric choke?

sj[/quote]

Folks, I really appreciate all the pointers, this community is a great source for ANY information!

thanks!

sj

qsmx440 said:

Steve I used to be a Honda/Johnson dealer. Seldom does throwing parts at a troubleshooting situation solve the problem. You need to seperate this into a fuel/ignition problem first. You are lucky in that it sounds like the engine has a radical problem as opposed to a "nuance" problem like the thread where the guy is having a oil temperature problem with his SC. I think Harbor Freight has an inline ignition testor. It has a neon light loosly coupled to the spark plug wire. Rig a couple of those inline with your spark plugs and see if the spark goes away with the problem. One caveat on that, if the plug is fouling out from rich fuel the tester can lie sometimes but it's a start. Next thing to do is get the engine running and then set it where it dies or runs badly and shut it of quickly and pull the plugs. Are they black and sooty (weak spark or air/fuel problem)? Wet (probably spark problem (did the lights go out on the inline testors?)? Dry definently fuel/air delivery (clogged fuel system (likely), compression loss for some reason(least likely))? Large difference between two plugs colors (swap ignition system components between cylinders if you can) DO a compression test- wide open throttle while turning over with starter. Should be aty least 150#. Test it hot too. I am not familiar with the Yamaha outboard but if similiar to the engines I used to work on the ignition systems were seperate between the two cylinders so highly unlikely that both would go intermittent at the same time. The plugs tell all on that. Hope these ideas help get to the bottom of this. Dave

Click to expand...

Score +1 ----helpful

So one of our fine members Tptailwheel who is also a rabid boater stopped by his buddy the Yamaha mechanics place and this feller said that he could guarantee it was one of two things:

1. The little tiny jet in the bowl ( 28 ) was gummed up.

2. The diaphragm in the bowl (30) was messed up.

So I guess I will tear off the carb this afternoon and see what's going on in there... AFTER I call the to see if they simply just stuck the whole carb in a cleaning tank, or if they took it apart and cleaned it.

sj

Oh......You wanted the inside of the carb cleaned???

DOH!

carb

I assumed you had already taken the carb apart and cleaned it well. Do this first, blow the jets out with compressed air, be careful so as not to blow other stuff apart. Pull the needle out of the jets, etc. 9 times out of 10, you will find a very small piece of crap in the one of the jets. float bowl, etc. If you can get a carb rebuild kit for this one, I would just get it and install it while you have it apart. Usually this kit is a new diaphram, o rings, etc. While the carb is off, confirm fuel flow to the line feeding the carb. These little engines are really quite simple to take apart, and not much can go wrong. Mine was an exception. I'm leaning against an electrical issue, but anything is possible. Murphy's law states it will be the most expensive part, my case confirmed Murphy was correct. Russ

I just confirmed that the place that did the work on this completely disassembled the carb, ran wire through it and carb cleaner, and got all the junk out of it. Then it ran perfectly in the shop for 45 minutes (I trust these guys). So the carb has been completely gone through - as it was last year by another outfit - and still has this issue.

I may just wait for the experts...

sj