I have a 4HP, 4 stroke Yamaha outboard for my inflatable Avon 260 dingy. This weekend got it out for the first time this season. Have not yet changed oil or spark plug. Last December, I ran all the fuel out and left it hanging on the boat like I have for the past 3 seasons. After putting in new fuel, it started on the third pull! Problem is, I have to leave the choke out about 1/2 when under load or it chokes out like it is starved for fuel. Ran it for about an hour yesterday and it never did function normally. The choke almost acted like a throttle in the mid third of it's range, but even after an hour of operation, if I closed it fully it would die. My plan is to change the oil and filter next weekend and also change the spark plug. Any other suggestions as to what is happening? Should I put a fuel additive into the gas that would clean out the carburator? Thanks for any suggestions.
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Outboard Problem
The condition that you describe is a sure bet that your needle & seat (carb) is dirty and sticky. If you are lucky a generous dose of "Stabil" along with some methylhydrate may clean it up. Otherwise you will have to take apart and either clean or replace the needle and seat.
The condition that you describe is a sure bet that your needle & seat (carb) is dirty and sticky. If you are lucky a generous dose of "Stabil" along with some methylhydrate may clean it up. Otherwise you will have to take apart and either clean or replace the needle and seat.
Going Forward
In the future you may want to fog the engine in the fall to prevent the glazing of the fuel in the carb. But it sounds like a fouled carb.
In the future you may want to fog the engine in the fall to prevent the glazing of the fuel in the carb. But it sounds like a fouled carb.
Dirty Carburator !!!!!!
At the end of this season, fill the tank with STABILIZED fuel, then run it dry .... and then remove the needle valve or bowl drain plug - squirt in some isopropyl alcohol and slosh it around then drain. Use "Stabil" or other fuel stabilizer to the fuel before you shut down for long term. You inadvertantly left UNSTABILIZED fuel which was either in the main jet orfice or one of the airbleed passages ... and the fuel 'soured' and formed gum/varnish in that passage. Simply 'draining' or 'running dry' will often leave teeny droplets in the passages or around needle valves, etc. ... and what remains will quickly form gum and varnish. At the end of THIS season, use STABILIZED fuel, then drain, etc. etc. etc.
At the end of this season, fill the tank with STABILIZED fuel, then run it dry .... and then remove the needle valve or bowl drain plug - squirt in some isopropyl alcohol and slosh it around then drain. Use "Stabil" or other fuel stabilizer to the fuel before you shut down for long term. You inadvertantly left UNSTABILIZED fuel which was either in the main jet orfice or one of the airbleed passages ... and the fuel 'soured' and formed gum/varnish in that passage. Simply 'draining' or 'running dry' will often leave teeny droplets in the passages or around needle valves, etc. ... and what remains will quickly form gum and varnish. At the end of THIS season, use STABILIZED fuel, then drain, etc. etc. etc.
Thanks for all the suggestions.
I thought it was probably the carburator. Thanks for all the suggestions on how to fix it. I'm going to try to dissolve it first. Next year I will most certainly use Stabil in the fuel and fog the engine! Where can I get some methylhydrate and how do you use it?
I thought it was probably the carburator. Thanks for all the suggestions on how to fix it. I'm going to try to dissolve it first. Next year I will most certainly use Stabil in the fuel and fog the engine! Where can I get some methylhydrate and how do you use it?
Carb Cleaner
I had the same problem at the end of last season. It probably is the new ethanol fuel that is causing this problem. I was able to "fix" the problem by adding automotive carb cleaner to the fuel and running it through. Let some of the cleaner fuel stand in the carb overnight and run it some more.
I had the same problem at the end of last season. It probably is the new ethanol fuel that is causing this problem. I was able to "fix" the problem by adding automotive carb cleaner to the fuel and running it through. Let some of the cleaner fuel stand in the carb overnight and run it some more.
Sea Foam
Try Sea Foam before you tear down the carb. Lest you think it is mere snake oil, read on... "Sea Foam Motor Treatment has been around since 1942, and was originally developed to remove varnish in carburetors in outboard engines. So the product has been around virtually forever, and is now used as a fuel injector cleaner, carburetor cleaner and all-around cleaner for anything touched by gasoline or diesel fuel. It's also claimed to be a fuel stabilizer, an engine top lube, dry gas and de-icer." quoted from an review by and admitted skeptic. Here is a link to the review. http://www.webbikeworld.com/sea-foam/
Try Sea Foam before you tear down the carb. Lest you think it is mere snake oil, read on... "Sea Foam Motor Treatment has been around since 1942, and was originally developed to remove varnish in carburetors in outboard engines. So the product has been around virtually forever, and is now used as a fuel injector cleaner, carburetor cleaner and all-around cleaner for anything touched by gasoline or diesel fuel. It's also claimed to be a fuel stabilizer, an engine top lube, dry gas and de-icer." quoted from an review by and admitted skeptic. Here is a link to the review. http://www.webbikeworld.com/sea-foam/
Got some Sea Foam and will try this weekend!
Will try the Seafoam on the carb this weekend. Thanks for all the comments and suggestions.
Will try the Seafoam on the carb this weekend. Thanks for all the comments and suggestions.
Jerry, if Seafoam doesn't work,
Unbolt your carb and send it to me. I'll fix it. Your carb is very small, obviously. That means the passages for fuel and air are small and more prone to restrictions from contaminates. Your idle or low speed passages are the smallest and also the ones that have been fouled. When you have to apply the choke in order for it to run, that means NO fuel is flowing in the idle circuit. The choke uses the high speed main jet for enrichment when the engine is cold and that is hard to foul. Of course, your problem is also extremely EASY to repair. All carbs work the same. Send it over.
Unbolt your carb and send it to me. I'll fix it. Your carb is very small, obviously. That means the passages for fuel and air are small and more prone to restrictions from contaminates. Your idle or low speed passages are the smallest and also the ones that have been fouled. When you have to apply the choke in order for it to run, that means NO fuel is flowing in the idle circuit. The choke uses the high speed main jet for enrichment when the engine is cold and that is hard to foul. Of course, your problem is also extremely EASY to repair. All carbs work the same. Send it over.
Fred - you are amazing!
If it doesn't work, I will take you up on your offer. I'm not much of a mechanic myself, but can probably take it off. I would glady pay you for your effort. You are a great guy!!!!!!!!!! This forum is fantastic.
If it doesn't work, I will take you up on your offer. I'm not much of a mechanic myself, but can probably take it off. I would glady pay you for your effort. You are a great guy!!!!!!!!!! This forum is fantastic.
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