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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15684
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have a 2004 Yamaha F50TLRC with a starting problem. I am

Customer Question

I have a 2004 Yamaha F50TLRC with a starting problem. I am looking for a mechanic to walk me through methods to diagnose the problem so that I can likely repair it myself. This engine has had a problem on cold starts pretty much since we bought it new
in 2006. It barely ran last summer. This spring I did all the routine maintenance including putting new spark plugs in. I also pulled the carburetors, dis-assembled and cleaned them. I started it up today for the first time this Spring. It ran for about 30
seconds and died as the idle speed decreased. Now I cannot get it started. I am running recreational fuel with yamalube added at the prescribed amount.
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** am I speaking with?
Couple of questions back to you. First is why are you running 2 stroke oil in a 4 stroke engine, and how much oil are you running?
Next, you said you pulled and disassembled the carbs. They have to be synchronized a very specific way with a carb balancing tool. How exactly did you go about syncing the carbs?
Also, how old is the gas?
Customer: replied 2 years ago.
Hi Jason,My mistake, I added ring free to the gas, not yamalube. I am running yamalube 10W30 engine oil. 2.5 liters plus a touch more to bring the level closer to full on the dipstick. I used the attached steps to synch the carbs. I am using new recreational fuel in a new tank with a new fuel line.
Expert:  Jason replied 2 years ago.
Hello. Where did that picture come from, which manual?
Customer: replied 2 years ago.
It is from the Yamaha F50A, F50T Service Manual. Cover picture attached.
Expert:  Jason replied 2 years ago.
Okay that's not the manual for your engine, you have is known as an F50C. Not that it matters that much as they all sync the same way.
Are you familiar with what a carb syncing tool is?
Customer: replied 2 years ago.
I do also have the F50C manual. I'll refer to that from now on. I guess I was looking at the wrong manual since I assumed my F50TLRC engine used the F50T manual.Yes, I know what a carb synch tool is. I don't own one but I can purchase or rent one if you can tell me what to get. Would something like this work? can't seem to find something similar on Autozone's website. I would prefer to buy one at Autozone or other store today, or rent one today rather than wait for a shipment.
Expert:  Jason replied 2 years ago.
That tool will work. This is the one I have, this one is called the Carbtune, and this is what all the pro's use. They come form the UK and take about 2 weeks to get, but they work fantastic .
To be honest I don't think autozone would have something like this. The only cars that ran multiple carburetors like that would be things like 1970's Ferraris. You are more than likely either going to have to order one from Amazon or a tool company. Or see if any motorcycle store in your area carries a carb syncing tool, as all motorcycles need these in order to sync those.
After that the process is on page 4-23 in your manual. Hook up the gauges. Start and run the engine and let it warm up. Get the engine to idle as low as you can without stalling, and then adjust the throttle plates on 1 2 and 3 so that the vacuum matches #4. As you get closer and closer you can turn the idle speed down. As you turn the idle speed down it is common to have to re-adjust the throttle plates, so if the jump a little on you as you turn the throttle down that is normal.
And that's it, that is how you do it. Did you have any other questions on the carbs or do you think that covers it? --Jason
Customer: replied 2 years ago.
Yes, I cannot currently get the engine to start. It started once and ran for about 30 seconds. So, what steps should I take to try to get the engine running so that I can do the carb synch? I have checked that the fuel pump is pushing fuel out and it is. I did not do any testing beyond that. Also, I did not check the prime starts in the carburetors as the manual describes.Thanks
Expert:  Jason replied 2 years ago.
Oh... It won't start at all?
Have you checked spark and compression yet? How old is the fuel? Will it run on starting fluid?
Customer: replied 2 years ago.
I detected a fuel line leak that I had not noticed before. I replaced all fuel lines. I had only replaced about half of them before. Now, when pressing the main fuel line bulb I can see gas dripping from one carburetor. I did not use new gaskets since they all looked good. Please allow me a few days to fix this fuel drip and I will touch base with you again. I plan to buy new gaskets so it may take me a few days to get them. The engine did start up again today and ran pretty well for about half a minute and then died.Thanks
Expert:  Jason replied 2 years ago.
New gaskets are a must. Also make sure you are using the correct clamps on the fuel lines or else you will have leaks there as well.

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