Yamaha won't start

[shy]

My Yamaha T9.9 will not start. Previously, I installed a 10 micron filter inline,
replaced the engine filter, put in fresh gas, and tore down the carbs which looked clean and cleared the jets. I am using my former Force metal gas tank
because the Yamaha 6 gallon will not fit into my fuel locker. It looks clean inside, but maybe the fuel intake is a problem. There appears to be some fuel in the carb because some leaks out when I open the carb drain. Could the fuel pump still be responsible? Can I easily swap out the fuel pump, if that is the
problem? I also believe the carb mixture screw is turned all the way into the
carb housing. I never touched it, and I assume it is ok since it was set by an
outboard mechanic. Is there an easy way to determine if the fuel pump is the
problem? This 2002 was running fine a month ago. I did not see any appreciable amount of dirt in the carb, but could I have missed something, since I did not soak it in any solution, just checked for clear idle and high speed jets being open.

 

[robert graham]

Re: Yamaha won't start

Go back to the air, fuel, compression, spark, formula, one of those is missing. Check your starting procedure, fuel primer, fuel enrichening device(choke or other),spark at plug, throttle position while attempting to start. The motors have gotten leaner(fuel mixture) over the years and everything needs to be just right for that fuel/air mix to burn. Good Luck and let us know what you find!

 

[shy]

Re: Yamaha won't start

I should have been more explicit. The engine will start and run for a few seconds if I spray something like Seafoam into the air intake. Seems like I have a fuel starvation problem. I can pump up the squeeze bulb till hard, and
I see fuel in the Racor 10 micron filter. I suspect there is still a blockage somewhere in the carb despite having cleaned the jets and sprayed in Seafoam. I am going to try another attempt at cleaning the carb insides with Gumout. The carb may require a soaking in a special cleaner, but to do that,
I have to completely disassemble the carb, which I am nervous about doing,
and buy a rebuild kit, all of which becomes a big deal for me. If there is some
fuel in the carb, does it indicate the fuel pump is still working? Will the bulb
be able to force fuel past the pump? Without special guages, is there any way to verify that the fuel pump is working?

 

[Pokertrampp]

Re: Yamaha won't start

I had the same problem on my 2000 9.9.

There is a little diaphram with a spring (on the bottom of the carb) it had a pin hole in it and did NOT come in the carb kit I purchased. When I replaced that it ran fine and have had no other problems since. good luck.

 

[shy]

Re: Yamaha won't start

Thanks for the tip, but can I be sure this will fix my problem?

I found a diaphram and spring on the parts blow up that appear to be some where below the float. Does anyone have any idea the function of these parts? Did you figure out what happended to your damaged diaphram? Was
it broken down with gasahol, or what? Can I see visually that mine is damaged on inspection, like a tear in it?

 

[Pokertrampp]

Re: Yamaha won't start

Thanks for the tip, but can I be sure this will fix my problem?

I found a diaphram and spring on the parts blow up that appear to be some where below the float. Does anyone have any idea the function of these parts? Did you figure out what happended to your damaged diaphram? Was
it broken down with gasahol, or what? Can I see visually that mine is damaged on inspection, like a tear in it?

It is the accelerator pump, and mine was damage from the ethanol so the damage was obvious.

Also, the jets are very small so make sure you use compressed air when cleaning them, mine would not run correctly with just spraying carb cleaner thru them, after I tore it back down and used compressed air I found it idled a lot better. although I still had to replace the accelerator pump and then it was perfect.

I would get a carb kit and clean the carb very well and put it back together and see how it acts before buying the accelerator pump as it is around $40 for that little piece of rubber. Your carb is not as complicated as it looks, and you have the diagram to help you reassemble it.

Where do you live? Maybe I can help if you are nearby.

 

[shy]

Re: Yamaha won't start

Thanks for the offer. We had our boat for many years in Islamorada, the Florida Keys, but now we moved it North to Racine Wisconsin.

The first time I had this kind of problem, I took it into a good mechanic in Racine, who unfortunately is now retired. I watched how he inserted a fine wire into both jets to get it running. The next time that there was this problem, I took the carb apart and used the same proceedure. It worked then. Now, I tried the technique again, but no luck. I still have to check the
delivery of fuel all the way from the tank to the carb. If that checks out ok, then I will try to clean the carb with something like Gumout. My last resort may be to replace this accelerator pump. However, you were at least able to get the engine running without a good one, and mine won't run at all now. I will let you know more after I visit my boat tomorrow.

 

[Pokertrampp]

Re: Yamaha won't start

Will the bulb be able to force fuel past the pump? Without special guages, is there any way to verify that the fuel pump is working?

When you pump the bulb, your filling the carb bowl with fuel, when the bowl is full the float rises and forces the needle intothe seat and stops the flow of fuel. so the answer is yes the bulb pushes fuel past the pump and into the carb.

The easiest way to test the pump is disconnect the line and crank the motor (disconnect the kill switch/lanyard so the motor does not start) and watch for flow. be sure to notice if it is a weak or strong stream.

 

[shy]

Re: Yamaha won't start

Was out at the boat today. Ran a few simple tests. Squeezing the bulb with the fuel line open at the filter produces a strong stream, so I can eliminate everything from the boat filter back ( inline filter, bulb, and 6 gallon tank).
Running the engine with the safety disengaged and the fuel line open between the carb and the fuel pump produces a small pulsating stream. I figure if the pump membrane were damaged, it would fill up with fuel and nothing would come out. That leaves the carb. For the third time, I took off the carb and opened it up. I gently poked a fine wire through all openings and sprayed generously with Gumout. The result was no improvement.

I finally found an independent outboard mechanic nearby the boat. He will be
meeting me at the boat tomorrow to see if he can get it started. I think the solution will be a complete carb teardown and cleaning, but I will wait to see
if he finds something else.

In addition to Yamaha not really re-engineering this carb, they are making it
very difficult to get parts. There is a big distribution center for Yamaha in
Pleasant Prarie near my boat in Racine. They provide no pickup or over the
counter service. Even independent repair people must go through a Yamaha
approved outlet to get parts. What a waste of time and inconvenience to the
Yamaha owners.

 

[Pokertrampp]

Re: Yamaha won't start

That leaves the carb. For the third time, I took off the carb and opened it up. I gently poked a fine wire through all openings and sprayed generously with Gumout. The result was no improvement.

Taking it off and spraying it with carb cleaner and just poking the openings is not enough all you are doing is pushing the debris further into the carb.

I think the solution will be a complete carb teardown and cleaning.

You are correct, that is the ONLY way to clean it, I am very confident this will solve your problem.

This 2002 was running fine a month ago.

I assume this means it sat unused for a month, are you using regular pump fuel? If I do not run mine at least once a week (even with a fuel additive) I have to open the carb and clean out all the crap from the ethanol. It does not take a long period of time sitting to upset the way the carb functions. I have since started running the motor out of fuel before letting it sit more than a week without use, this has helped considerably.