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Posts: 311
Location: Ontario | Mine hasn't given me a hiccup in five years of heavy use. Long runs, rough water, early season ice, late season ice and a lot of trolling. This year there's definitely something not right. It clunks a bit at low idle (not a piston clunk, just runs rough) and is very sloppy out of the hole. Hesitates, instead of jumping right out. At the RPM range I normally run at, about 3500 to 3800 (@ 26 miles an hour) it runs rough, like it's starving for air, gas or both. If I jump up to 4000, it runs fine. A few things I have eliminated so far:
1. Last year's gas with stabilizier. Used the same exact routine every year for five years, no changes. Ran thru 2 full, fresh tanks since ice-out and it runs the same, crummy.
2. New plugs this April. Swapped them out after they ran rough with last year's plugs. Still runs rough no matter what plugs, this years new or last year's old.
3. Added a bottle of gas line antifreeze to burn out any moisture this past wknd. Still runs rough.
4. Fuel filter is a sediment bowl that's easy to get at. Clean as a whistle.
5. Air intakes are clean.
Guys I've talked with say that the carbs might need a cleaning after 5 years. I think more and more of the gas I burn is inferior quality, too. There are also little bowls off each carb that might contain water if I pull the covers. I'd like to avoid a $200 bill for a guy hooking me up to the diagnostic machine at the marina for a five minute session. Any tips or places to look that I haven't? Thanks in advance. The motor is a 2003 Yamaha 4 stroke on a 17' Lund console. |
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Posts: 1769
Location: Algonquin, ILL | I have a 2001 Merc 90HP 4-stroke, last spring mine did the same thing, what I found is that the squeeze bulb was bad, sounds wierd I know but the Mechanic I usually use told me that when the bulbs go bad they let just enough Air into the gas line so that at lower RPMs the motor is starving for gas but at Higher RPMs the fuel flow is high enough to keep it running smoothly, Don't know if this will fix your problem but it is a cheap fix and worth trying
Good Luck
Edited by JohnMD 5/20/2008 6:12 PM
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Posts: 311
Location: Ontario | Didn't check that one John, but I sure will now. It's gotta be something simple like that. My rig is well-maintained and at her age, something small like that going belly up would not surprise me. Thanks for the reply, I'll have a look at it this wknd. Anyone else? |
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Posts: 1769
Location: Algonquin, ILL | One other thing you may want to check is the fuel pick-up screen in the gas tank it may be clogged, the problem with that is you will have to take up a portion of your floor to get at it
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Posts: 1095
Location: Hayward, WI | You may want to try running a "shock" treatment of Yamaha Ringfree in your gas, it may help. Also Yamaha now has a remote 10 micron fuel filter that you mount between the fuel tank and the primer bulb that really helps cut down the number of fuel related issues. |
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Posts: 392
Location: KY | Do you have a fuel/water filter? A friend had the same problem you described and fixed it by replacing that filter filter. |
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Posts: 311
Location: Ontario | Thanks for all the replies. As far as I've been able to tell from people, the sediment bowl is the 'fuel filter' on this unit. I have to think that there's at least one somewhere between the ball and the tank's pick up, though. Something else has to filter the fuel.
More and more people I've talked with are suggesting a shock treatment of carb cleaner for my next trip, mixed a little on the heavier side with the fuel. Safe to try? You hear so much conflicting info re: 4 strokes. I was told to never fog in the fall, fogging works well. I was told to never add fuel stabilizer, it hasn't given me trouble so far either. Thanks guys. |
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Posts: 3504
Location: Elk River, Minnesota | Hi Everyone,
I'd take the shock treatment a step further... Mercury powertune or a seafoam equivalent sprayed directly into the carbs while the engine is running High idle... spray and spray until the engine finally wants to die (lots of white smoke)...let the motor die, and spray another 4 seconds into each carb. Let the motor sit for about 25 minutes, then take her out and run it open for a while to burn all the gunk out. That should clean the cylinders and the cylinder walls, along with some gunk on the plugs (if there is any build-up). After the procedure, the motor should run smoother at all RPM levels...
Also, with the bulb...that makes sense too...so before going out and buying a new one, if you have a separate tank with a different hose, try that first....if it runs well, you've found your problem.
Steve |
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Posts: 311
Location: Ontario | Thanks VMS, this is exactly what I'm doing in about three hours...running the tank from the 25hp Yamaha on the duck boat to my 90hp. Adding Kleen Flo and going to run her thru a tank. I think I will know right away if mositure or the ball is the issue. I have the option of dropping the boat off at the marina Saturday afternoon the get the carbs taken apart and blown out also, +/- $300 they said. I want to eliminate all the small, cheap stuff first. Thanks again for the replies. |
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Posts: 311
Location: Ontario | Over the wknd, I ran a 5 gallon tank with it's own ball+hose and fresh gas thru my motor with a bottle of Kleen Flo anti-moisture treatment. I ran 3/4 of the tank using the new hose/ball and she still ran the same. So I'm thinking it has to be a blocked/gummed jet in the carb. I dropped the boat off Sunday at our Yamaha dealer and can pick it up in about two weeks.I know that there are different jets for low, mid and high speeds, my high speed is working well, the other two not so much. Thanks for all the tips, I'll report on the findings when I pick the rig up. |
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Posts: 5874
| Wow, 2 weeks? That is a bummer. Hope they get it right the first time. |
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Posts: 311
Location: Ontario | I could be waiting a lot longer than that. Middle of May in Ontario's busiest cottage country I'd say I got off easy! The rigs were parked 2 deep in the storage compound at the marina, probably 100 boats in there. Everyone wants the same thing at the same thime this time of year. This marina is 80 minutes from 2.5 million people too. |
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| Yep, it's gotta be the carbs. I have a 2001 Yammy 80 and so does my buddy.
We both have had to have the carbs cleaned and both been told that when the ethanol sits in the carbs is gummed them up big time.
I had my carbs cleaned last year for the first time, so not bad after having it for 6 years. |
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Posts: 311
Location: Ontario | Thanks for all the replies. My boat's ready after two weeks wait, thet had it fixed in a couple hours. There was a fair ammount of gum in the carbs. They were disassembled, cleaned, tunes and reinstalled. The water test went well at the marina, and I'll be picking it up thie Friday. Two weeks until we can fish for 'em up here, it will be good to have the boat back with a couple weeks to spare. After five years, the carbs did need cleaning, and ethanol gas does leave more gunk than gas without. Hope everyone's motor runs well this season and thanks for all the tips. |
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| Try running seafoam mixed in every few tanks of gas to keep the carbs clean going forward. This especially helps when the boat is going to sit for a few weeks. Of course, if you only have the problem every 5 years perhaps it's not too big of a deal. |
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Posts: 311
Location: Ontario | Thanks buddy, you're the second or third guy now who's said good things about that Sea Foam. Gonna ask about it when I pick up my rig Friday.
Edited by JBush 6/12/2008 12:18 AM
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Posts: 311
Location: Ontario | Put over 75 miles on the motor after getting it back from the shop this Friday. It ran like brand new after they cleaned out and adjusted my carbs. Thanks guys, it sure felt goog having her back. This wknd I'm going to install an inline fuel filter. It won't do much help with ethanol gas but it will help if any grit ever gets into the tank. |
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| I had the same problem with ethanol, except had to replace the carburetors.
I only use non-ethanol fuel/recreational fuel in south florida. All marinas now carry recreational fuel due to the demand from the boaters.
Another Alert!
I have a Yamaha 90 hp 4 stroke, I believe 2003, the last year with carburetors.
Last week testing engine for summer research and ran well until I came in. Engine shut down but restarted after an hour.
Cranked right up by the boat mechanics who then noticed that the Voltage regulator and the CDI appeared to have caught fire since the entire system was melted. They have never seen this before.
Has anyone heard of this happening before?
We are a non-profit volunteer organization who unfortunately have had consistent problems with this engine. Very expensive to fix! |
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2003 90 hp Yamaha 4 Stroke