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Tohatsu MFS 8 / 9.8 SHUTS OFF

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Fernandodgalindo69

New member
Motor was working fine 2 weeks ago. Today it didn't want to start. I changed plugs, fuel filters, checked for air vacuums and then it started but had to keep it reved high. When lower the gas....it would run and shut off. Then it doesn't start up anymore. It has oil and fuel. Can anyone please help me. Also the start switch turns on and then thats when it stops working.

Please help. The Motor is about 2 to 3 years old and is always maintained.
 
Odds are you have crud in the carburetor. You are under warranty, for non-user-related items. If you have the dealer inspect/repair it, any factory defects will be corrected free of charge. However, if you left fuel in the carb for 2 weeks, and that varnished it up, it is not a warranty repair.
 
pvanv said:
Odds are you have crud in the carburetor. You are under warranty, for non-user-related items. If you have the dealer inspect/repair it, any factory defects will be corrected free of charge. However, if you left fuel in the carb for 2 weeks, and that varnished it up, it is not a warranty repair.
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Hi Paul, i took carb off and cleaned it. ...although it wasn't dirty. After finding out it was a 2008 motor and out of warranty. Carb is clean as a whistle, but still doesnt fire up. I checked for current going out of the coil, by placing a screw driver and having my friend pull the cord. It sent a charge but i was not jolted hard. So i assume it could be the ignition coil that doesnt send enough juice to get the plugs to spark to cause the combustion needed to make the motor run. Whats your take on this? Can you tell me why it doesn't stay and could i be on the right path. Thanks again in advance.
 
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If it runs at high RPM, you have spark. What method did you use to clean the carb? You would want the Factory service manual to run electrical tests on the CD, exciter, pulser, and ignition coils if you want to test ignition.
 
pvanv said:
If it runs at high RPM, you have spark. What method did you use to clean the carb? You would want the Factory service manual to run electrical tests on the CD, exciter, pulser, and ignition coils if you want to test ignition.
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I took the carb off and took it apart. I used carb cleaner and i also added the gas treatment 1oz per gallon. It turns but wont fire. I will look into running electrical tests to the other parts you mentioned and see if they all check within the numbers indicated. Ita not much to the little motors, which i am stumped.

Thanks again for the info
 
Fernandodgalindo69 said:
I took the carb off and took it apart. I used carb cleaner and i also added the gas treatment 1oz per gallon. It turns but wont fire. I will look into running electrical tests to the other parts you mentioned and see if they all check within the numbers indicated. Ita not much to the little motors, which i am stumped. Thanks again for the info
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In the first post, you indicated that it ran, but only at high speeds. That is typical of a clogged low-speed circuit, or other condition causing a too-lean mixture.

Just spraying with generic carb spray is not aggressive enough to clear the organic varnishing that can accumulate if fuel is allowed to sit in the carb for a week or two. Gas treatment is about as effective as a magic wand. Stabilizer will delay "rotting" of the fuel, but if you use fresh gas, that's not much of an issue.
 
pvanv said:
In the first post, you indicated that it ran, but only at high speeds. That is typical of a clogged low-speed circuit, or other condition causing a too-lean mixture.

Just spraying with generic carb spray is not aggressive enough to clear the organic varnishing that can accumulate if fuel is allowed to sit in the carb for a week or two. Gas treatment is about as effective as a magic wand. Stabilizer will delay "rotting" of the fuel, but if you use fresh gas, that's not much of an issue.
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i did take the carb apart and used the carb cleaner to scrub. but seeing that everyone i have asked in the retail stores and also your suggestion of the carb issues on the first reply, i have purchased the kit to do my carb over again and clean it out with carb cleaner and also possibly using some of the 1 gallon acid cleaner to dip all the parts to make sure its 100% clean and rebuild it again and see what that brings me. i hope it starts up right away and we are back in business. i want it for the 4th of july day to take the family and most importantly for a troop of scouts that want to earn their boat badge on the 16th of july so i have to have it running by then.

thanks again Paul
 
low speed jets were mentioned,crud builds up in them,sometimes cleaner,solvents are not enough,try a copper wire in there.A lean running engine can cause expensive repairs
 
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johnnygjr said:
low speed jets were mentioned,crud builds up in them,sometimes cleaner,solvents are not enough,try a copper wire in there.A lean running engine can cause expensive repairs
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No. Never ever push any wire through any jet in any carb. There is a possibility of scratching the walls of the jet, leading to weird mixture issues later. A 4-hour soak in real carb dip, followed by a liberal spray-out with generic carb spray won't hurt the carb.
 
If the motor is currently an MFS8, and if the problem persists (will not idle), and if the boat can handle 9.8 hp, another possibility is to install the carb for a 9.8, thereby gaining 22-1/2% power.
 
pvanv said:
If the motor is currently an MFS8, and if the problem persists (will not idle), and if the boat can handle 9.8 hp, another possibility is to install the carb for a 9.8, thereby gaining 22-1/2% power.
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Thanks all for the helpful hints. I went out and bought a carb kit and carb cleaning solution to deep all the parts in amd used highpressure air to do a final clean. 1 of the needles had some gunk although the air still passed. But after the deep soak it and cleaning....the motor started right up. I turned it of numerous times and it would start on the first pull. Idled perfectly and runs really smooth again. In a side note, there were 2 needles that need to be removed and cleaned thoroughly. Work in a very lit area, as i missed one the first time.

I am glad it all worked out for me and thanks again for the advise. Happy scouts on the 16th .....woot woot.

Thanks again.
 
hi again. I have a new problem now. I went to catalina and there was no wind. so I motored all the way back for the most part. right by los Alamitos by long beach, ca....my motor stopped working. the reversed worked but not the forward. after getting to my slip and calling it a night, not the forward or reverse don't work. the motor turns like a champ, but can not accelerate or move the forward or reverse lever. can you give me some direction as to what I should look at first in order to repair my outboard. the last suggestion to do a cleaning of the carb worked wonderfully and hope you can also help me with this request.
 
I also have a coworker who has a mercury merc 1250 for sale and want to know if that big outboard would be too heavy for my 25ft lancer sail boat or would be ok, as I seen smaller fishing boats with huge motors. please advise or what your suggestion is. thank you again.
 
Fernandodgalindo69 said:
hi again. I have a new problem now. I went to catalina and there was no wind. so I motored all the way back for the most part. right by los Alamitos by long beach, ca....my motor stopped working. the reversed worked but not the forward. after getting to my slip and calling it a night, not the forward or reverse don't work. the motor turns like a champ, but can not accelerate or move the forward or reverse lever. can you give me some direction as to what I should look at first in order to repair my outboard. the last suggestion to do a cleaning of the carb worked wonderfully and hope you can also help me with this request.
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You may have a spun hub in the prop. That would mean the prop shaft is turning, but not the blades.
Otherwise, you could have a bent shift linkage, or damage to the LU.

Are you saying that you cannot move the shift lever into either F or R? That sounds like a shift linkage problem.
 
Fernandodgalindo69 said:
I also have a coworker who has a mercury merc 1250 for sale and want to know if that big outboard would be too heavy for my 25ft lancer sail boat or would be ok, as I seen smaller fishing boats with huge motors. please advise or what your suggestion is. thank you again.
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Not a chance. It weighs as much as the boat. You must be kidding.
 
I found the issue. Or part of it. No more linkage issues. I did find a bad propeller that had a bad bushing and replaced it. So it spins and the boat moves back amd forth but when it is in neutral, a lot of bubbles or water bubbles atop even though its idle. It should be clear and still as if the motor was off, but its more like if the prop is spinning. Would u say its a gasket, seal, bearing? Thanks again for the help.
 
Sounds like the RPM is a lot above idle. Idle should be under 1000 RPM. As Johnny said, looks normal. The exhaust is supposed to go through the hub, except for a small amount that goes out the idle port.
 
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