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'85 90hp Yamaha 3 cyl

I noticed last time out the engine died on me when I shifted into reverse. This happened only once. Today I popped it in the water let it warm up the normal amount of time and then it proceeded to die every time i shifted into reverse or forward.

Unfortunately, this problem chose to happen while rescuing a guy off of his overturned 19' sailboat! The mast was stuck in the mud and he was bobbing around in his life jacket. Upon maneuvering to scoop him up the engine died and wouldn't start again! It was blowing 15k and i luckily got the kicker going in time before hitting the breakwater of the marina.

I spent the next 30 minutes running the motor and at idle it would just slowly lower loose r.p.m. and eventually sputter out.

I brought it back home changed nothing, put it on the muffs and it idled great, and shifted into rev and forward without dying every time. Sounds like a fuel issue but where do I start?

D

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dmrose,

I had a similiar problem with my 1986 3cyl Yamaha 40. Essentially, I took the three carbs off and removed the bowls from each of the three carbs. Then I used some carb cleaner and sprayed the jets with it. After I did that, I thoroughly cleaned the rest of the carbs with the cleaner. After I reassembled the carbs, I started the engine and slightly adjusted the idle so it would idle at just a little higher RPM than it did before. Solved my stalling problem and that was 1 1/2 months ago. You may have something clogging your carbs. It doesn't take much to clog up one of your jets.

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I would start by checking all fuel connections for restrictions, or clogs. Does the bulb prime? Was this a new tank of gas? if so try switching tanks. Do you have a water separator? If so time to check whats in it...

There is small plastic water separator/filter near the oil tank. I would empty this into a glass container and check for contamination and clean the filter (be careful have paper towels on hand gas will drip out). If there is water then you will need to drain the carbs...

This is fairly easy, on the opposite side of the engine you will see brass nuts at the bottom of each carb, they will need to be opened up and drained. Be very careful, do not drop them into the cowl...:o Actually they will drain slowly if just opened enough..

Then run seafaom through it at a high concentration in a 6 gal tank (aviod the spray type) you really need to have this stuff run through the carbs, soak, and sit in the bowls. You can operate the boat in the water while you do this.

BTW, I never never need to prime my Yamie, bulb always seems firm. Have you done service recently, Fuel pump should be changed every few years.

If this does not help then you may have deeper problem, carbs may need rebuild, and need to come off. You may also want to have the compression checked, although if there was an issues it would not idle normally.

Good luck

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joninnj,

Very good advice as usual.

Let me just ask one question. Lately I have taken to increasing the throttle to get it started from being cold. Is it possible to flood the engine even if it is running? To the point where it would run at a very low idle and then eventually quit or die when shifted. When I got it home is just ran awesome on the muffs, and this was approximately 20 - 30 minutes later. I also started it without giving it gas... My small engine newbieness is definitely at work here.

D

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Hmmm, had a thought.... You said you let it warm up before heading out, and I assume it was warm the day it initially died on you, but when it ran well on the muffs after the problem, was it cold?

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Yes, it was warm while I struggled with it at the marina. When I got it home, i'm sure it had cooled down because I had to strap it to the trailer and drive home which probably took 30 to 45 minutes. Frustrated, I immediately put it on the muffs, didn't prime the bulb, and turned the key. It fired right up and idled great. When I shifted into forward and reverse there was no sign of it wanting to die.

D

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I also found my invoice from the last servicing on the motor.

On 10/07 I had the motor spark checked, compression checked, new plugs, carbs removed and cleaned, cleaned fuel filter and fuel lines, checked thermostat, and ran the motor in a tank to adjust the carbs. This is a reputable company and i dropped $310 for the above.

D

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D, I would try the above process. Does not look like the pump was changed when you serviced it. This is not a part replaced every season. Also have you changed to fuel line lately? I had a yamie connector go bad once leaked just did not work... Drove me nuts.

While you are doing above... (the seafoam thing) check for any leaks, and frequently check the bulb, If is soft and limp...(sorry) B)... That would point to a worn the fuel pump. Easy fix, not an expensive part. PM me if you would more help.

Sure does sound like a fuel delivery problem...

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Back pressure in the leg of the motor is much greater when in the water. When on muffs the engine will run on a leaner mixture. Richen up each carb by turning the mixture screw 1/4 turn counterclockwise the first time. If this doesn't solve it , try 1/2 turn counterclockwise. Hopefully this solves the problem. ghostrider

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Also some motors of that era did not have adjustable idle jets. There is a cover over each fixed jet , through which you can spray carb cleaner if you can get to them. Other wise you have to take the carbs off the engine and clean the idle jets. A good job for a mechanic of your choice. ghost rider

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Okay checked fuel filter for water. No dice. Checked all fuel connections to the motor and all seems good. I'll check the jets and try some Sea Foam tonight. Also, not sure on where/how to adjust the idle up a little bit. I broke out my old maintenance manual and am still a bit confused.

D

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How did the plugs look?

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Idle adjustment is on the top left on the carb as you face the engine. Small brass screw with a point and spring also connected to the throttle linkage. Turn very slightly.

If it idled fine last week and suddenly not not fine now, I doubt raising it will do much to help this. Mine idles at 800/900 RPM, and 600/700 in forward.

Hopefully a high does of seafoam will help (I mean high does like the whole can in 3 or 4 gallons) It will smoke...

I know this may sound stupid but is the vent screw open, I've done this, just last year...:D

Screw vibrated to the closed position...

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Vent screw is open, but leaving it closed is definitely within my capacity! The plugs looked slightly wet, but overall pretty good. Grey to charcoal in color. I will try overdosing with Sea Foam and see how it goes....

D

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D,
You might also check the pickup screen in your tank just to get that off the list of probables. It's an easy one.
Mike

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I did check the pickup in the tank and it was clear.

Last night i mixed a pint of Sea Foam into 4 gallons of gas and ran it at about 1000 RPM for 15 minutes. I then dumped that 4 gallons into my main 28 gallon Tempo which had about 12 gallons in it. I had not added any fuel conditioner to that batch so I'll run this and see how it goes. If i still have some problems I'll run some directly into the carbs.

Thanks for all of the help/suggestions!

D

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Is the fuel line running the right way (arrow on bulb facing away from tank toward's engine). I ask this because, I've accidently put it on wrong, and the engine acted much the way your's did. I also have a friend that had similar problem's as you described, intermitently the engine would bog at high rpm and almost stall, he lost his mind replacing Fuel pumps, pick up screen's and other part's, the problem remained. One day he saw strange circles on the interior foam inside of the engine cover, "Space invader's" ? NO ! The foam sound deadening material had come loose, and everytime he powered up, the carb's would suck the hanging foam up against themselves stalling the engine out. The spring's also get weak on the fuel line connections at the tank, and motor. I had one get weak and sometimes it would hang up and not press open the fuel connection needle (fuel starved) but, only "sometimes", then it did it almost every time I went out until I found the problem. Do you have another fuel line you can try ?
mw

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Seafoam rocks! I ran her over 30 nautical miles today and she ran like a champ. Definitely the best 7 bucks i've ever spent. Thanks all for the help!

D