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Problem w/ 98 150TRLW Carbed V-max

red32131

New member
Well, I am new here and things aren't good with my boat. I am hoping that a service guy or someone with the knowledge can help me out. Strap in, here we go...

98 150tlrw carbed engine.

Problem:
Surging, at speed motor will surge. Not seeing increase on tach just in the seat of the pants.
Bogging, at take off boat will not jump up on plane. This just started this past weekend.
Loss of top speed, normal top speed for boat is 58-60mph, yesterday I could not get it over 50mph.
Running rough, at idle the boat sounds rough there is a sheen in the water as if I am loosing gas or oil into the water. 2 weeks ago I cleaned under the motor in the cowell and I am not seeing any new drips.

List of checked items and repairs.
Carbs rebuilt last year.
2 sets of plugs last year.
Fuel filter replaced.
Fuel lines checked. (no issues)
New fuel pumps 2 years ago. (checked those and no leaks)
Sparks coming from all 6 plugs when checked.
New water pump this spring.

I am not sure where to go from here... ANY help would be greatly appreciated.
 
So you have a hot spark from all plugs. New plugs thatshould be good for years and years, fuel pumps working, etc. The one key itemin your post was "Carbs rebuilt last year". As it is spring... lastyear is last year and this Obamathol crap we have to deal with is making a messfor all all of us. Did you winterize? Did you fog the engine, and pull the gasline and burn all that Obamathol crap out of your engine? If not... I would betthat you have a clog or a partial clog in one and probbably more of those brassfuel jets in your carbs. They are little pin holes and just a little partialblockage will give you problems. This ethanol crap makes a mess of those jetsjust at it does my Yamaha 4stroke fuel injectors and every other filter I'vehad to replace in my engine. If you are handy, it is a simple fix... buy a canof carb cleaner, pull the carbs, and blast that cleaner through the jets. Onething you DO NOT WANT TO DO is run that 2 stroke engine lean on one or morecylinders or you'll fry the rings or the piston in those cylinders. I've beenthere and done that!
 
Thanks for the reply. I have not been good in the past with fogging the cylinders and properly winterizing. I have been good about using seafoam and sta-bil ethanol treatment.

After talking to the shop today, he said to run a heavy dose of seafoam through it and see if that gets better. Sounds like he is on the same path you are on with a possible clogged jet. He said if that does not work, to bring it to him. I am sure that he is thinking he will do the same.

I am going to try that and see what happens. I am thinking about bench cleaning the carbs myself to see if that works.

First thing first is finding a good manual that will show me the way. Any suggestions?
 
You can search the net for the repair manual... some places offer a free download of the sevice manual for $8 or something. Google "1998 Yamaha 150 VMAX Service Manual" and see what shows up. Seafoam is highly regarded but I only use it as a fuel additive. Sometimes it works with a high dose and sometimes it doesn't but it is hit or miss. With a 2-stroke, you don't want to get back to a state with a high Seafoam dose in a small tank of gas where you are OK with the performance and then forget about it or you may end up with a cylinder or two running just a bit too lean. Too lean in a 2 stroke = not enough gas/oil mixture lubricating the rings = not enough oil = ring failure in time. Nothing can compare to an afternoon of pulling the carbs and cleaning them with pure carb cleaner. Don't be afraid... this ain't rocket science. If you can take it apart you can put it back together. If it still doesn't run well... nothing is lost and you can pay the big $.

Pulling and cleaning carbs is not a big deal and you shouldn't need a manual to do it. Look at it this way... if it becomes too much you can always throw all the parts in a 5 gal bucket and take everything to the mechanic who may cut you a break since you saved them time on pulling all of them. Alternatively, if you pull all the carbs you can probably find a place that will clean them for you cheap and hand them all back to you for you to reinstall. What usually clogs is the tiny brass fuel jet with that pin-hole orifice. Most carbs offer easy access to that brass jet that lets you unscrew it with a screwdriver if you wish. It will stand out.. believe me. As long as you are going to pull all the carbs though, you may as well clean everything so buy like 4-5 cans of carb cleaner. Carb cleaner is cheap, certified yamaha mechanics are expensive.. VERY EXPENSIVE. Spray it through everything and keep on spraying it into every hole you can find. Then, shake it out and spray spray spray some more. Spray so much that you wouldn't want to do this in a closed area on a bench! One thing to remember about those brass jets... don't try to ram something through that little orifice to clear it that will scrape the inside of it. If you scrape it, you leave a microscopic grove that can serve to attract gumming and clogging in the future. I've used a thin piece of copper wire before as I figured copper is softer than brass so it shouldn't scratch it and I've had no problems but many say not to stick anything through there and just let the carb cleaner do all the work.
 
great reply! thank you.

i have purchased a service manual today. my plan is to try the seafoam treatment first. if that does not do the trick,i will buy a gasket kit and pull the carbs myself to clean them. with the detailed information i have at my fingertips now,it should be a task that i can complete fairly simply.

thanks again for the reply!
 
If you end up pulling the carbs, I'd bet you won't need the replacement gasket kit. The service manual for the yamaha techs probably says to replace them but that is yamaha talking to its service techs and looking to sell more gasket kits which your local yamaha dealer/service center loves to do after marking them up as does yamaha who supplies them with the gasket sets. I've pulled my carbs and cleaned them on prior 2 strokes many times without replacing the gaskets. I'd bet your existing gaskets will work just fine if you end up pulling them and putting it all it back together.
 
My advice... spend the time, pull the carbs, and clean them all well... Then you know for sure that the carbs are not the problem and you don't run the risk of the Seafoam thing bringing your engine back to acceptable operating levels with a potentially slightly lean fuel/oil charge feeding one or more cylinders. I just went into the depths of my yamaha F115 4 stroke to the point that I wondered if I'd get the thing put back together... I had the 5 gal buckets full of parts and somehow got it all put back together (without any parts remaining) and then came the final test... WILL IT START? Sure enough she fired right up and I fixed my problem after 6 hours of wrenching. The local yamaha service center wanted close to $1000 for labor and parts that I did in six hours with about $150 of replacement parts. You can do this simple carb cleaning... Don't be scared. Until you push yourself, take them apart, put them back together, and watch it fire up... you'll never build confidence. 2 strokes are simple engines. Fuel, Air, Compression, Hot Spark. You have all those, it will run.
 
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