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I have twin 96 model 115 proV yamahas on my 24' grady. I bought the rig second hand and after about four trips had problems running at idle. Took it in and had the carbs boiled out and rebuilt on both egines. Gummed up fuel and accumulations on the low speed jets were the culprits. Since then I have run about 900+ gallons of fuel and have kept the canister filter changed and added stabil each fueling. My port engine on the last two trips is hard starting. To cold start it requires no choking, and no throttle. I can smell it flooding out. When it does start, I have to keep the rpm's up or it will stall. It runs great at cruising speed. When I back off to circle a spot it will stall unless I keep the rpms around 2000. what would cause it to flood out or run so rich?
 

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Worldangler
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I know EXACTLY what the problem is...

...cause I've been fighting it myself with a pair of '96 yammies on my offshore rig. Here's your problem:

That year/design of yammie (caburated oil injection) has a poorly designed carbs. There are some VERY tiny holes drilled into the carbs that are used as air channels to regulate the air/fuel mix. There's a needle valve that adjust the air space. The smaller the hole, the greater the vaccum that is created and the more fuel that is pulled.

Unfortunately, these small holes can clog/gum up very easily. This causes a high vacuum, which flood the engines and makes it impossible to run at lower RPMs.

Along with that problem, the yammies have an extremely good fuel filter system. This makes the fuel at the engine very pure.

Very pure modern gas formulas will evaporate extremely quickly, and will leave a gummy residue behind - clog these "air idle" screws and channels.

I've been fighting this problem for years trying everything - but just like you -would only get a few trips before the engines (a) wouldn't idle, (b) very hard or impossible to start, and/or (c) loss of top end performance. I was having to have carb rebuilds twice/three times a year (a $500 a pop) and immediately have the cleanings, the motors ran great.

I tried Sta-Bil, carb/injector cleaner - you name it with little or no results. However, I ran across a yamaha motorcycle guy who immediately knew the problem and gave me the solution. Run 'em bone dry at the ramp before you take the boat out of the water. Shut the fuel off/disconnect the line (whichever is appropriate on your rig), run the the RPM's up to about 2000-2200 and run 'em until they die and cannot be started. This will suck all the fuel out of lines/carbs/channels.

I've been doing this since January and the problem has all but disappeared. For extra measure of protection, I somtimes put a heavy does of Stabil in my nearly empty tank on the run home and use that tank when I hit the jetties.

An alternate solution is to mix oil with your gas - the oil will keep the gas from evaporating or gumming up. A good idea when the boat will be sitting for an extended period of time.

Also, I found there's no need for an expensive carb overhaul if you currently have the problem. Dunk, from the *** board, sent me some instructions that do a pretty fair job of cleaning the carb air idle stuff while the carb is on the motor - you can do it yourself with a screwdriver and a few cans of carb cleaner. I've gotton good enough that I can do all 12 carbs on my two motors in about 45 minutes. PM me for more information on this procedure.

-john humbert
 

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Worldangler
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Woody...

....I will send you the info, but I'm a little tied up at work...will send as soon as possible or you can call me later tonite.
 

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Woody



Johm is rite on. I built my carbs several times and found out later with a screwdriver and carb cleaner and an air compressor I could fix the problem without removing carbs. Not sure how mechanical you are but it can be done.



Charlies
 

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PRI-G rather than Stabil..

you might look into using PRI-G as a gas treatment rather than Stabil. Google up their website and read. Lots of gas (and diesel -diesel uses PRI-D) owners are switching because it cleans and prevents built-up. Has been used by commercial users (tugboats, etc) for years.

Howard
 
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