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  #21  
Old 03-22-2008
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I had the same problem with my Tohatsu 8Hp. It was the ethanol clogging my jets. Had to clean the carb and used additive after that. If you can find any 100 octane racing fuel (ethanol free) run a tank of that, it will clean out the carb. Use additive after that, if your gas is going to sit for a week or more. Personally, I think your better of using it all the time.

Bob C s/v Valkyrie, Irwin Citation 35.5
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  #22  
Old 03-24-2008
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Service manuals for each brand are available from their respective dealers. The generic manuals often have errors and fail to address some aspects of repair on individual models. Clean the carb by taking it apart and soaking the appropriate pieces in carburetor cleaner. Nothing you can spray into it will dissolve the plugged jets and ports. Spray cleaners should be looked at as a preventive maintenance item rather than as a repair tool.
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  #23  
Old 03-25-2008
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I haven't read the whole post yet . . . .

. . . . so I hope I'm not wasting your time.

Quote:
Originally Posted by ysabelsdad View Post
I have a 5 horse Mercury that is doing something very similar. Can anyone recommend a decent book on maintaining and repairing small outboards. Most of the book I have seen seem to be oriented to larger engines.
Try this site. It costs 15 odd dollars but I down-loaded the Mercury 1989 to 2000 manual and I'm really pleased with the result. This covers all models of Mercury from 2.2 hp to the big daddies.

Technical Download PDF / Text Suzuki GSXR 1000 Service Repair mercury

Andre
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  #24  
Old 03-25-2008
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By now you have probably found the problem but here's a quick fix that often works for this type of problem.

Take off what you need to get to the inlet of the carb - run the engine up to a reasonably high RPM and then while holding the throttle open, block the airway (I try to use the palm of my hand).

The vacuum has to be drawn from somewhere and often it will draw bits of rubbish through the main jet and clear it. If it doesn't work, you haven't wasted too much time.

Andre
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Old 08-21-2009
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Just found this thread the other day while trying to fix my friend's Tohatsu 3.5 2 stroke. What the problem turned out to be was the petcock was blocking the fuel flow to a few drops a minute when full open. Unable to disassemble it but there seems to a rubber washer or check valve that only allows fuel to flow in one direction. It was either gummed up or swollen from the ethanol and would allow just enough fuel to idle but not enough to get to half throttle.
Sprayed carb cleaner let it soak and blew it out with compressed air.
Motor now running better than it has in years
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Old 08-21-2009
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To avoid this problem

To avoid this problem in the future, if it is jet stopped up from crud, which I think you will find to be the cause. When you finish for the day with the engine, shut off the fuel and run the carb. dry. Modern?? gasoline is horrible, and while sta bil will keep it usable for some time, when it evaporates, still leaves junk behind, which stops up jets. Running it dry will eliminate this problem.
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Old 08-22-2009
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I found a tip from a motorcycle forum for dirty carbs.Buy a can of flammable carb cleaner.Drain out all of the gas from the motor.Put enough carb cleaner in the tank to run the engine.Start the engine and run until the carb is full of cleaner.(make sure the proper amount of oil is mixed with it if it's 2 cycle)Shut the engine off and let it sit for a day.Take it for a run with fresh gas and see what happens.
This saved the Triumph motorcycle owner $450 ($150)per carb.Costs $5 to $10 bucks.Make sure the cleaner is ok with plastic parts,it should be written on the label.

Phil
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  #28  
Old 08-23-2009
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That's not a great idea. Most carburetor cleaners will dissolve the rubber and plastic components of the average carburetor. The only safe method is to remove the carb off of the engine, take it apart, dip the metal parts in carb cleaner for at least three hours, wash off, blow dry and re-assemble.
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  #29  
Old 08-24-2009
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I have a Johnson 3.5 internal tank on my 525, always shut the gas off, run the gas out of the carb, raise it and tilt it , place the sunbrella cover over the engine. I've done that for over 12 yrs. It starts on the third pull and runs strong. Try to find 100% gas, we just have a few stations that still sell it in our area. Only problem to date, watch out for the mub dobbers, they will make a nest in the strangest places like air cleaners or water exit tubes...
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Old 08-24-2009
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Mentioned elsewhere in this thread (and Sailnet) is the fact that alcohol (the 15% of E85) eats rubber. (try this experiment at home - pour some isopropyl alcohol into a dish, put a peice of black rubber - say a peice of an old windshield washer into the dish, let stand for 12 hours. Do you see any change in the rubber?)

The problem with this motor is most likeley that some rubber in the fuel supply (gasket, fuel or vacuum line) has partially dissolved and is either gumming up the carb, or causing a vacuum leak.

The FIX is to identify the damaged rubber component(s) and REPLACE it(them) - preferably with a like component that is not affected by alcohol. Rub a Q-Tip over suspect parts. If the cotton turns black, or gets little gooey black blobs on it, then you've found a problem. Then clean the rest of the fuel system (needle valve seats, venturi, jets, etc.).

The best preventitive measure is to run the motor dry, but then you may have to worry about corrosion. If this is a concern, then spray a can of motor fog into the carb before storing it.
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