Yamaha problems.

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jmbadge

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In the begining season I ran into some ethenol problems ,since then I have drained and dried the tanks replaced water seperator several times.
Also checked and drained the filter at the engine filled with fresh fuel and treated with proper additive. Checked all gas related options had mechanic check for fuel flow to the engine and go over moter he found nothing wrong. while under way on this 2005 yamaha 150 2 stroke she purges ,hesitates, sometimes stalls has a hickup and a puff of smoke at times on idle. While underway she will run great but after 10 min she acts up again. Its almost like its starving for fuel.. Any thoughts would be greatly appreaciated..
 
did you try runing off an external tank bypassing the boats fuel system?

If you have the same results on an external tank, it is something in the engine needs to looked at..
 
Have you looked at the primer bulb to see if it is collapsing?
 
Haven"t tried external tank yet, The fuel line is new after the water seperator . I also checked the downtube that's in the tank with no obstruction. While running under load the primer bulb is full and not collapsing. The engine only has 35 hours on it is it possible that it could be engine related ?
 
Check the fuel lines, make sure you gas tank vent is clear and allowing the tank to breath if all are OK then think about replacing the fuel pumps?

Have a Yamaha mechanic go over the engine before you start guessing at solutions.
 
When you "Drained the filter" did you drain it in to a clear container?? You need to be able to see the fuel and see if your getting water.
I don't drain filters unless they are the Racor type with a built-in drain at the bottom. Try replacing the filer. BEFORE U DO -- use the primer bulb to "siphon off" some fuel in to a container that you can see thru. This will allow you to see if you have a water problem. Your original filter may be saturated to the point where it's by-passing water in to the engine.
If there's water present --- YOU'LL SEE it in the bottom of the container.
 
The first time Ive drained the filter there was water present since then I drained and dried the tank Problems still exist. Ive noticed that the new filter is a bitch to get off when I only hand tighten it after running. Having a mechanic meet me tomorow to test fuel pump and carbs.
 
You could have a small amount of crud in the carbs. It doens't take much on these engines. Each float bowl setup is actually 1 small carb for each cylinder.
I went thru a huge mess with fuel problems last year after the boat set for a long time. I had the carbs off BOTH engines 4 Times. I'm very experienced at working on carb engines and used to build/race chevy small blocks w/ 500+ HP.
These 2-strokes drive YA NUTZ!
The last time the carbs came off, I had spoken to a very experienced Yamaha mechanic. He showed me the proper way to check and reset the float levels. I found 3 of the 12 floats out of spec by more then 2.5 mm on the high side. This creates a low fuel level in the bowl and causes the engine to starve. I'm lucky I didn't toast a cylinder or two.
If you pull the carbs, get a carb gasket set -- you'll need it given the age of the engine. PM me and I'll give you directions on how to do this if you feel inclined.
As for the filter -- ALWAYS put a small amount of oil on the gasket and smear it around until the entire gasket is coated -- Then install HAND TIGHT. BE SURE to check for leaks the first time you start the engine and a couple of times after that.. My filters are easy to see and change and I check for leaks EVERY TIME I run the boat. I always keep a rubber strap filter wrench on the boat and 2 spare filters per engine.
 
I keep 2 strap wrenches, getting the plastic bowl off the Racors can be a PIA. When I rebuilt my carbs, not 1 float bowl was set up properly from the factory. Just keep the parts organized and count the turns of the mixture screws.
 
I hade the carbs cleaned this past week hopefully that fixes the problems. I am thinking that at the end of season I will drain and dry the tank and start fresh next spring. Who wants to deal with ethenol problems..
 
If you want to do it right --- In the fall for winter lay-up I usually run the engines "Out-of-Fuel" with the fuel cut-off and then just squirt fogging oil in the spark plug holes. After I do all cylinders, I use a breaker bar and slowly turn the engine over a couple of times to spread the oil up and down the cylinders and the put the plugs back in lightly tightened.
In the spring, remove the plugs and spin the engine over with the starter for a couple of seconds, with the hose hooked up so as to not damage the impeller, and then replace the plugs, prime and start her up.
 
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