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Reluctant engine start
Took my Yamaha 9.9 4 stroke out of storage (after 2 years) and tried to start it today.
It would not catch until I sprayed in some starting fluid, but then it would only rev up a bit and then die. I think it is getting sufficient fuel from a supply tank, but that is one thing to check. I ran the engine dry and fogged the carburator when I put it away last time. Could the fogging material be blocking one of the jets? Do I have to remove the carburator from the engine to clean it, or can this be done with the carburator attached to the engine? I was using fresh fuel, and this is an almost new engine, with about 20 hours on it. Somewhere I saw a recommendation to partially or fully cover the air inlet to assist in getting fuel to the engine. Is that a good idea? Sherwin D. |
On Fri, 15 Jul 2005 23:59:22 -0500, sherwindu
wrote: Took my Yamaha 9.9 4 stroke out of storage (after 2 years) and tried to start it today. It would not catch until I sprayed in some starting fluid, but then it would only rev up a bit and then die. I think it is getting sufficient fuel from a supply tank, but that is one thing to check. I ran the engine dry and fogged the carburator when I put it away last time. Could the fogging material be blocking one of the jets? Do I have to remove the carburator from the engine to clean it, or can this be done with the carburator attached to the engine? I was using fresh fuel, and this is an almost new engine, with about 20 hours on it. Somewhere I saw a recommendation to partially or fully cover the air inlet to assist in getting fuel to the engine. Is that a good idea? Sherwin D. If an engine starts with ether, not otherwise, its a fair bet the fuel supply or carburettion is faulty. One at a time then: 1) fuel pump working? Pulsing fuel out of an open hose? 2)Is this a float chamber carb? If so, has the float stuck up? Has the float needle stuck up? 3) Has the inlet manifold sprung a giant crack? A little leak? .....you get the picture. Brian Whatcott Altus, OK |
sherwindu wrote: Took my Yamaha 9.9 4 stroke out of storage (after 2 years) and tried to start it today. It would not catch until I sprayed in some starting fluid, but then it would only rev up a bit and then die. I think it is getting sufficient fuel from a supply tank, but that is one thing to check. snip Sherwin D. Sherwin, I went through a similar problem with the Yamaha 9.9 4-stroke on my Catalina 27 earlier this year. BTW, I usually use gasoline squirted into the air intake on the carburetor rather than starting fluid because the starting fluid can be hard on the engine. I fill an oil squirt can with gas and apply a couple of squirts into the air intake when I want to start it. Obviously be careful with the raw gas, and don't get a fire started. You can convince yourself that there's a problem with your fuel delivery by keeping the motor running with carefully timed squirts of gas from your oil can. If the engine runs when you squirt in gas, and then dies when you quit, there is a problem in your fuel delivery system somewhere. Did you pump the primer bulb really well to make sure that fuel got all the way to the fuel pump? If so, it may be that your fuel pump membrane has cracked, and is not pumping fuel to the carb. You can check this by unclamping the fuel line that runs from the fuel pump (back of the engine) to the carb at the fuel inlet barb on the carb, and cranking the engine. If fuel comes gushing out, the pump is working, and the problem is with your carb. If the problem is with the carburetor, it is likely that both the idle and main jet are plugged with fuel debris. If either jet were clear, the engine would get enough fuel mixed in the air to allow it to run although possibly not like it should. Copy and paste the following link into your browser, and it will bring up an exploded view and parts listing for the 1996 Yamaha 9.9HP 4-stroke carburetor. http://www.boats.net/yamaha/partsyst...5dc715ee20c05c You should be able to find a similar diagram and parts listing for _your_ carburetor on this site as well. If you are mechanically inclined, you can take the carburetor off, clean it out with lacquer thinner, unplug the jets, and reassemble it. If you are _really_ careful, you can do all of this and still use the original gaskets--I did ;-) You'll need to use a small piece of wire to run through the jets to clean out the crap. These are the parts labeled 8,9 (Main jet and nozzle), and 5 ("pilot" = idle jet) in the exploded drawing. I use q-tips dipped in clean lacquer thinner for cleaning the inside of the housings. Don't get the lacquer thinner on the plastic parts or the gaskets. If you are not mechanically inclined, this is the time to get re-acquainted with your favorite outboard mechanic and get ready to cough up some bucks. Note that a whole new carb only costs $301.49 + shipping, so don't let the outboard shop gouge you for more than that to rebuild your old one. Good luck with it, Don W. |
sherwindu wrote in
: or fully cover the air inlet to assist in getting fuel to the engine. Is that a good idea? Wanna bet the inside of the float carb looks like it's coated in shellac from the evaporating fuel left in it? Running it until it stalls only gets part of the gas out of the float bowl. The rest turned to shellac and clogged the jets so it runs way too lean. Government bureaucrats and Greenies made this worse by demanding manufacturers limit how far you can screw the jets in and out...as if that made any difference in the pollution of the planet from jet aircraft and power plants and solar wind. So, you can't unscrew the main jet any more until it melts the shellac away like you "ustacould way back". The main jet isn't even adjustable and the idle jet only turns half a turn.....how stupid..... -- Larry |
Hi Larry,
You are possibly right about the floats, although in preliminary discussions with outboard mechanics, they point the finger at the extremely fine jets in the 4-stroke engines. One mechanic said gasoline dries to a powdery residue, which then can become imbedded in these jets. This problem seems peculiar to 4-stroke engines. My former 2-strokes never needed a carburator cleaning or rebuild. Why is this sensitivity of 4-strokes one of the world's greatest secrets? I would have taken extra pains to run something like 'Stabil' through the carbs before storing the engine. I might have not bought a 4-stroke if I thought they would be so problematic. I checked the engine today and gas is definitely coming out of the hose that supplies the carborator. I will probably have to get my boat towed to the nearest mechanic. I hope they don't have to remove the engine from the boat to do this job. Sherwin D. Larry wrote: sherwindu wrote in : or fully cover the air inlet to assist in getting fuel to the engine. Is that a good idea? Wanna bet the inside of the float carb looks like it's coated in shellac from the evaporating fuel left in it? Running it until it stalls only gets part of the gas out of the float bowl. The rest turned to shellac and clogged the jets so it runs way too lean. Government bureaucrats and Greenies made this worse by demanding manufacturers limit how far you can screw the jets in and out...as if that made any difference in the pollution of the planet from jet aircraft and power plants and solar wind. So, you can't unscrew the main jet any more until it melts the shellac away like you "ustacould way back". The main jet isn't even adjustable and the idle jet only turns half a turn.....how stupid..... -- Larry |
Lionheart has a 5hp Nissan driving a 12' Fold-A-Bote. You're right about
the tiny carbs. Too tiny. The throat of it is about the size of a pencil. All the components are very tiny, indeed, including jets. Diesel-fuel-in- a-can like Stabil is nonsense. Save money and just put diesel fuel into the float...same stuff. Gas doesn't "go bad" unless you let the tank breathe in and out so the lighter elements can escape, leaving behind the heavies. There's a 1987 Honda 5KW genset in my shed that has gas in it from Hurricane Hugo in 1989 in a STEEL tank. The tank is kept full with new gas, probably a pint. It will crank on the 2nd pull on 1989 gas. If you're going to run the engine a lot and leave it in place, 4-stroke is fine. Running it will keep the tiny float carb clean. But, if you're going to transport it a lot or use it infrequently, I think a SIMPLE 2- stroke that doesn't have some damned computer that requires a systems analyst with special equipment to repair is much better. Premix gas has OIL in it. OIL doesn't evaporate when the gas does, keeping the carb all greasy and protected. The 10:1 in that Seagull protects everything from the tank to the exhaust, covered in a film of motor oil. Doesn't take a rocket scientist to see why. sherwindu wrote in : Hi Larry, You are possibly right about the floats, although in preliminary discussions with outboard mechanics, they point the finger at the extremely fine jets in the 4-stroke engines. One mechanic said gasoline dries to a powdery residue, which then can become imbedded in these jets. This problem seems peculiar to 4-stroke engines. My former 2-strokes never needed a carburator cleaning or rebuild. Why is this sensitivity of 4-strokes one of the world's greatest secrets? I would have taken extra pains to run something like 'Stabil' through the carbs before storing the engine. I might have not bought a 4-stroke if I thought they would be so problematic. I checked the engine today and gas is definitely coming out of the hose that supplies the carborator. I will probably have to get my boat towed to the nearest mechanic. I hope they don't have to remove the engine from the boat to do this job. Sherwin D. -- Larry |
sherwindu wrote:
One mechanic said gasoline dries to a powdery residue, which then can become imbedded in these jets. I though smoking dope in outboard shops was prohibited. It is corrosion or other residue clogging the smaller jet size. It comes down to what Larry said but there's no such thing a powdery residue from clean gasoline evaporating. |
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Larry wrote:
Put 3" of brand new gas in a gas can..... Sit it out in the sun so the gas will boil off like it does in your float carb.... Notice it's STILL GAS that leaves shellac in its wake.... But not powdery residue - unless it's been used as a solvent for other illegal purposes in said shop. :-) |
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