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Two weeks ago my son took my boat offshore. Only rules I have is that it comes back with more gas than it left with and it also comes back cleaner. He called me a few miles out claiming the engine was not very powerful.

Since then I've been trying to figure out why the 2000 150 caburated Yamaha has lost 20% of its power. The boy said it was fine, but started performing poorly once they got about 5 miles out.

I'm a fair mechanic and have found several potential problems; bad spark plug, corroded connection to a coil, silted gas filter, and full water filter. I've gone over air, spark, and fuel systems several times. The I asked the boy what type of gas they used. He said Citgo. "Oh tell me you didn't," I replied. The only gas worse for a 2 cycle engine than Texaco is Citgo. At least that's what I heard about Citgo and have personal experience with what Texaco would do before they merged with Chevron (Techron).

So now I had a theroy that it was a problem with the gas. I've heard some companies are putting high percentage of alcohol in the gas. After 5 years of hard running I had my carburators cleaned earlier in the year. Could the carbs be gummed up this quickly?

So thats the question. Has anybody been experiencing problems with the new gas formulations? I tried some gas treatment (Sea Foam) yesterday to no avail. The engine is idling like new but after a 30 mile run with the magic juice still is low on power.

I've only been to the mechanic 4 times in my 45 years and 3 of those were because I was too lazy to do the job myself. Looks like I'm going back. But before I do that, I want to ensure others are not experiencing something similar with the pressures to cut gas with alcohol.
 

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The first tank of gas with alcohol will break loose any gunk in the tank / lines that's built up. It comes off in small enough pieces that it might have plugged an injector (if you have fuel injected engines) or a jet on a carb.

The local distributor (I get my aviation oil from the distributor) told me that they've had a lot of complaints about 'bad gas' from that kind of problem. They also said that older rigs can have a problem with the fuel lines / seals.

I know alcohol can't be used in planes for that reason. Some of the older fuel lines / seals can dissolve when the come in contact with oil and my distributor said they've seen that same problems with gasoline with 10% alcohol (the only kind you can sell now in any county that touches Harris). They're going over to Sargent to fill their small boat (20') to avoid the problem.

gary
 

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Just a guess

All the major companies seem to up the ratio of ethanol to gas in the summer. This is for price control first and environmental reasons second.
The ethanol has an affinity for water, its hydroscopic. Try new and/or doubling up on the filters for two stage water removal. Or a more drastic measure, pump the gas into your truck and try another brand in the boat before an expensive trip to the mechanics. Hope this helps been thru this with outboards before.
 

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Haynie HO/Merc ProXS
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I am running a 96 200hp Johnson with no apparent issues. I do use Sea Foam every other top off and have a water separator filter. I did have a friend use 92 octane in his engine and burned it up in 30 minutes. I forget the make, but I was stunned to hear the high octane gas would burn up some motors. New one to me. I always thought the higher the octane, the better. Guess not.
 

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Roll Tide!
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I've been running gasahol in my 2000 200 HP Johnson for a couple of months now with no ill efects at all. Power is fine and I set a new WOT high speed mark of 48.7 mph yesterday. If their is any difference, it's that it smokes less when I first start it.
 

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My yamaha 225 2-stroke is burning more fuel and seems to be showing more carbon inside the cylinders. The carbon is even thru all the cylinders so I don't think iy's tune up. I change the plugs every 50 hours or so and run a racor seperator before the engine. This doesn't seem normal considering we have been making some pretty good runs of 40 miles each way. I will probably run a good shot of ring free in it the next trip. ( and take some extra plugs.)
 
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