MyFishFinder Forum
MFF US Northeast => Maine => Topic started by: MarkNFish on May 20, 2019, 06:18 AM
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Based on past discussions I know there are some folks on here that are more mechanically-inclined than I am. I have a 1998 Tohatsu 25 hp 2-stroke outboard. I used it for the first time this season yesterday and while it starts fine and runs ok at high speed, it won't idle correctly. It smokes, sputters, and eventually stalls. I can keep it running by giving it some throttle, but that obviously doesn't work well for trolling. It was running fine when I put it away last fall, and I mixed fresh gas with Marine Stabil and some Sea Foam this spring. I use Marine Stabil in every tank.
When this happened a couple of years ago it took 3 trips to the shop for them to get it right, and since I don't want to lose it for the next month, I was hoping somebody here might have a suggestion. I suspect a carb issue but taking it apart intimidates me. The motor runs great when it's right, but this issue is getting annoying. Thank you in advance for any suggestions.
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Based on past discussions I know there are some folks on here that are more mechanically-inclined than I am. I have a 1998 Tohatsu 25 hp 2-stroke outboard. I used it for the first time this season yesterday and while it starts fine and runs ok at high speed, it won't idle correctly. It smokes, sputters, and eventually stalls. I can keep it running by giving it some throttle, but that obviously doesn't work well for trolling. It was running finseee when I put it away last fall, and I mixed fresh gas with Marine Stabil and some Sea Foam this spring. I use Marine Stabil in every tank.
When this happened a couple of years ago it took 3 trips to the shop for them to get it right, and since I don't want to lose it for the next month, I was hoping somebody here might have a suggestion. I suspect a carb issue but taking it apart intimidates me. The motor runs great when it's right, but this issue is getting annoying. Thank you in advance for any suggestions.
I'll take "dirty carb" for $200 Alex. ;D
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I'll take "dirty carb" for $200 Alex. ;D
Sounds right to me. Any "miracle juice" I can run through it? The Sea Foam didn't help a bit.
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Sounds to me like your low idle setting is dirty. I would MEASURE the screw turns on the low idle by screwing all the way in and unscrew it, push some gas threw it to flush it and reverse screw setting and try that.?
That little needle valve is very small, wouldn't take much to restrict gas flow, the good thing is you can't hurt anything by trying. ;D
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Sounds to me like your low idle setting is dirty. I would MEASURE the screw turns on the low idle by screwing all the way in and unscrew it, push some gas threw it to flush it and reverse screw setting and try that.?
That little needle valve is very small, wouldn't take much to restrict gas flow, the good thing is you can't hurt anything by trying. ;D
Thank you! I just might learn something in the process.
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Sounds to me like your low idle setting is dirty. I would MEASURE the screw turns on the low idle by screwing all the way in and unscrew it, push some gas threw it to flush it and reverse screw setting and try that.?
That little needle valve is very small, wouldn't take much to restrict gas flow, the good thing is you can't hurt anything by trying. ;D
MG 39 where would this =be? I am having very similar issues with my 2005 90HP Johnson. It starts fine but when in idle or low gear it shuts off. However, anything above low throttle and she runs fine. I realized that if I hold the choke in it revs up the engine and I can then shift into gear to get moving. I was thinking old gas but maybe my low idle setting is the issue as well. Any thoughts?
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Sounds right to me. Any "miracle juice" I can run through it? The Sea Foam didn't help a bit.
You can keep with the Sea Foam Mark but those ports are just so d**n small it doesn't take much crude to create a problem. You might get lucky but I doubt it will come out of it with just "miracle juice".
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You can keep with the Sea Foam Mark but those ports are just so d**n small it doesn't take much crude to create a problem. You might get lucky but I doubt it will come out of it with just "miracle juice".
You are probably correct Eric, but it's worth a shot.
For years I would always disconnect the fuel line at the end of the season and let the motor run completely out of fuel, and I never had a problem. I've been lazy the past few years and didn't take that additional step. You can bet I'll get back into the habit this fall.
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You are probably correct Eric, but it's worth a shot.
For years I would always disconnect the fuel line at the end of the season and let the motor run completely out of fuel, and I never had a problem. I've been lazy the past few years and didn't take that additional step. You can bet I'll get back into the habit this fall.
Exactly what I do bud because I have been down this road myself and it sucks. If you have access up there to non-ethonal gas, last tank of season would be that stuff. If not, go heavy on the sea foam last tank.
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Prob the ethanol the government and corn farmers force us to use.
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MG 39 where would this =be? I am having very similar issues with my 2005 90HP Johnson. It starts fine but when in idle or low gear it shuts off. However, anything above low throttle and she runs fine. I realized that if I hold the choke in it revs up the engine and I can then shift into gear to get moving. I was thinking old gas but maybe my low idle setting is the issue as well. Any thoughts?
As mentioned previously, sea foam, dry gas and stabilizers are needed with the poor gas today. Every motor is different in some way or another when it comes to carburetion. Everyone seems to have their own way of caring for their motors. I don't drain gas in any motor I own. I tried it once and had gasket problems from dryness? You should be able to find the screw adjustments for high and low but if it's fuel injection, that's another deeper, complicated issue. :(
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As mentioned previously, sea foam, dry gas and stabilizers are needed with the poor gas today. Every motor is different in some way or another when it comes to carburetion. Everyone seems to have their own way of caring for their motors. I don't drain gas in any motor I own. I tried it once and had gasket problems from dryness? You should be able to find the screw adjustments for high and low but if it's fuel injection, that's another deeper, complicated issue. :(
My experience has been the same with yours. Whenever I run the carbs dry, the small ports have more tendency to varnish and oxidize. I know this because I can see it with my own eyes when I have to take the carbs apart for a dip in Berrymans. Learned the hard way, with kids snowmobiles where they ride around the yard for literally days (not kidding, every waking hour, the same 20th of a mile loop around the house) until the sled ran dry. The carbs on these 120cc motors would varnish almost instantly in a hot engine bay. Got good at rebuilding those with a crying child looking up at me the whole time. I store with properly treated gas, tank filled to the absolute rim (no air to create condensation) and leaving the carbs wet with properly treated fuel protected against phase separation.
Also, in my experience, once a carb is running poorly due to corrosion or oxidation or buildup, no Seafoam or "miracle juice" is going to fix it unless you are really lucky. The carb must be taken apart and cleaned. The proper way to do this is to dip in a carb cleaning solution. You used to be able to buy good stuff, but now all I see commonly available is Gunk brand Carburetor Dip. It comes in a gallon paint can and has a small metal basket in it. You remove the carb and disassemble it completely, keeping a note of the jets that are externally adjusted as MG39 said above, count the amount of turns until it bottoms out so you know how to reset it. Soak in the dip for the recommended time, then I use spray carburetor cleaner with the little spray tube to blow out the carbs completely followed by compressed air.
But before that I would rule out a bunch of simple things. How old is your fuel line? If it's type "B" grey hose it's only good for 5 years. How about your connectors? Make sure you don't see any fuel leaking from them. It's not likely the fuel pump is bad if it runs with more throttle, but possibly. I would take it off and check the diaphragm- probably just replace it.
You say if you hold the choke in, it revs it up so you can shift into gear? Will the choke kill it if you keep it engaged? It should. If it does not, that would indicate to me that it is running lean which is not good for a 2 stroke engine especially. You may want to perform a plug chop reading. Get it started and running in gear at wide open throttle (in the water only, NOT on earmuffs) and then kill the ignition with it in gear. Remove the plug. If the electrode is white, you have a lean condition which is the biggest cause of 2 stroke motor failures. You want it to be more tan. Even black is better than white.