Tohatsu outboard problems

I worked with tohatsu on the height of the mount. no difference. I measured it and it ended up only being about 1 and 1/4 inch lower than stock.

Got back with tohatsu yesterday and they are stumped. They think the boat is two big for the engine and that is why the rpms are running 1200 rpm under nominal . Nominal being according to them 5500 rpm. They are sending me free of charge a 6 pitch prop to test and see what that does. They agree that I am not getting 6hp at the prop if im not getting 5500 rpm but I can tell they want to say it is because the boat is to big/heavy.

I have a new theory. The engine cranks and runs fine if it is a given that it is supposed to vibrate like it does. It produces just a little less power at the prop than the old engine. everyone I have talked to including tohatsu says that 4 strokes run just a slight bit weaker than a comparable 2 stroke. What if this engine just ended up accidentally having the jets for a 4hp version instead of 6 hp version installed. there is no physical difference in the 4hp/5hp/6hp engines other than how the carb is jetted. It would be consistent with everything that has been said and observed.

Anyway that is where it stands right now. I was going to return the engine this week but tohatsu offering to send the prop got me to agree to test that and see what the results are.

So far

  • I am happy with the customer service from tohatsu USA and Vic who I have delt with there.
  • I am unhappy with as they have not responded to my last request for help at all.
  • Based on Jons (from forums) experience i think this engine is a great price/weight/power option for our boats.
  • The fuel economy on this engine is awesome. I am getting 6+ hours of runtime on 2.5 gallons of fuel at WOT.
  • I think my experience with this engine is probably atypical and that there is an issue with this specific engine.
  • Either it is jetted wrong
  • or something is wrong with the electronic ignition advance at the top end.

Jon on the forums speaks up for being friendly and helpful with his purchases. Actually here is a quote “I had great friendly service from them, both with the purchase of the outboard & the prop.” (I thought I would add this in just to be fair.)

I posted this back

“They were not friendly or unfriendly when I called them with the problem. I got them the information they asked for and then they dropped off the face of the earth. I have not badgered them so It is possible that in general they are not like this but just dropped the ball on this one. I have been working directly with tohatsu USA because I got a better vibe and response from them. If I return the engine it will be to and I guess I will find out if it was a fluke or what by how they respond. ”

 “I would recommend buying from if you purchase online. They are within a few dollars price wise and miles better with support/attitude. I had a list of several online merchants I had priced when looking for this engine and when I started to have problems I called their number by accident. we quickly sorted out that I hadn’t purchased from them but the service guy there was really friendly and spent some time giving me advice even after we found out they had not sold the engine to me. I mentioned to Vic at tohatsu how helpful they were to me even though they hadn’t sold me the engine and he said they were a good company and that he had worked with them before on stuff.”

131 comments to Tohatsu outboard problems

  • Ralph Starnes

    I own a 2006 40 hp, Tohatsu, fuel injection, never have had any issues, until yesterday,the motor runs but idling very high, checked the throttle linkage,worked in back and forth by hand, could not get the motor to idle down ??? what do you think ?

  • I’m afraid I have never done this so not sure what to advise other than call tohatsu or a service center and ask them.

  • Not an issue I have delt with, however maybe the (can’t remember name) piece that adjusts air flow in throat of carb is sticking slightly open? Two things the throttle control is fuel flow and air flow. You’ve got to much air or both I would think. If it was just to much fuel I would think it would start smoking running way to rich at an idle.

  • Ralph

    Thank you, i’ll check that out

  • Ralph Starnes

    Thanks, i’ll chech that out

  • Ralph Starnes

    Thank you I appreciate your help I will check into it a little further

  • Doug

    Can not find solution to gas in oil problem it is a 2005 4hp 4stroke Tohatsu
    It started when oil smoke started coming out of the engine really heavily I checked the oil and found that it was overfull I used a small syringe to take some of the oil out it looks really thin runny so I completely drained the oil and added new oil it ran for about 20 minutes and then started smoking really badly again the oil was diluted with gasoline again
    Took the carburetor off check to make sure that the float was working properly and everything appeared to be fine. I used the turkey baster and emptied the oil completely almost all gasoline in the oil compartment this time at that point it started just fine I hadn’t put any oil in I thought maybe it wouldn’t start or would stop immediately but it didn’t after about 30 seconds I shut it down and they all oil compartment was full of pretty clean gasoline this time not sure what the next step should be

  • only place it can be coming from is the carb.. most likely a gasket. I would talk to a mechanic but I bet if you replace all the gaskets it will fix it.

  • Ronnie

    Scott I have a 2002 tohatsu 4-stroke 25hp that has a ghost in it,the motor idles like a champ until about 2/3 throdle then it starts to misfire I changed one bad ignition coil with a broken wire that made it run better at low speed but not at full speed.

  • wayne dovey

    Hi there,i have a 50hp tohatsu outboard that wont give me full revs.Seems like ican get the revs when engine is cold.Go fishing for a half hour restart the engine and cant get full revs on the way home?

  • not sure what would do that. maybe something like automatic electronic ignition advance or choke that is failing when hot? Hasn’t died totally but heat affects it? I’m just guessing here.

  • tj

    My 1995 30 tahatsu keeps pouring gas out the carb when pumping the ball it never gets tight like it should gas keeps coming out

  • I would rebuild or replace the carb.

  • Jim

    2002 5Hp Tohatsu serviced it myself and cannot get the drive shaft and the other rod to align to re assemble the lower unit.

  • Jim

    No information ????????????????

  • I haven’t done this before with mine so you probably need to see about getting a manual or maybe one of the more mechanic centric websites that have more indepth knowledge of disassembly and reassembly.

  • Jim

    FYI…it’s the alignment of the drive shaft to the motor drive. Long shaft keeps hitting the edge of the opening where the gears mesh.
    May have to disassemble the motor housing, agree mechanic must know the trick to get it aligned.
    Thanks anyway.

  • John Wilkins

    I have a 2017 4 hp tohatsu MFS4CDS MOTOR PURCHASED JULY 2017. usually starts the first time. However, hardly ever restarts without waiting long time (hrs) or next day. Serviced May 2109 at auth dealer & made aware of restarting problems. Still having restart problems. Also 2 time this past weekend it just stopped running while lout on the lake….not restarting. I have seen in some places that others have had restart problems….but never seen an acceptable solution. Any help here ??

  • Wish I knew something that would help. That was never one of my issues with mine.

  • Alan

    I have a 2005 90HP Tohatsu that starts easily and runs well at low-to-3/4 throttle, but when I go full throttle it looses power and stalls. Any advise or experience? Thanks.

  • Nothing specific but that it is the carburetor. Either how much air its getting or fuel. Hmm… could be ignition advance also.. I think those bigger engines are electronic ignition.

    First thing I would do is run some seafoam through the gass to clean out carb/jets.. also maybe a good carb cleaner kit that you can spray in the intake while it is running. I think seafoam has a product for this also? maybe. If that doesn’t work then your heading to ignition, automatic choke, carb rebuild troubleshooting

  • Sam

    I have a 2000 model 70 hp Nissan ns70c that has no power after 3500 rpms normally has 5000 rpms , motor doesn’t quit after 3500 rpms, just feels rough and misses! Have changed the plugs and run premixed gas straight into the carbs with the earmuffs on applying water out of the water didn’t change anything,, has done this intermittently for a year or so after running it up the lake for a while! But now it does this all the time ! Have checked the output at the plugs and you can see a blue spark below 3500 rpms but seems intermittent after 3500 rpms , coils all look ok and have cleaned the carbs with no change at all

  • Really sounds like an ignition issue. Maybe electronic advance isn’t working right?

  • Sam

    Thanks ! I will look into that

  • Brian

    I hit some rocks in shallow water with a tohatsu 20 outboard. Now the motor will not go above super low speed (even with throttle all the way up).
    Prop & water outflow look fine. It was a pretty hard hit.
    What could be the issue? Maybe something got jarred loose? Can I fix this myself or is this a service call?

  • ouch!!!.. sounds like maybe the prop is slipping on the shaft? you might have broke the key that holds it in place on the shaft. that is what it is there for. to break so that the gearing or engine further up doesn’t seize and break. If it’s not that then unless you feel good about taking apart your lower unit and then working your way up into the engine to see where the problem is then its a service center for you :)If it’s the key it is a few cents to a couple dollars to replace and easy enough for you to do if you haven’t damaged the shaft or prop by running it with it broken for an extended time.

  • Ian Wharton

    5hp Two stroke Tohatsu…..Had the gearbox off as it only goes into forward, forward where neutral should be, and neutral where reverse should be.
    This is by shifting the selector rod directly in the gearbox so its not a linkage issue. Internals of gearbox all look ok.
    The plunger that the shift cam looks ok. Has me puzzled.

  • Your into stuff I haven’t done before. Wish I could help.

  • Chris D

    Quick question for the group: just bought brand new tohatsu 40 hp four stroke for my whaler and it has been running fine for the first three hours of break in use—no issues no unusual wear or tear or problems, used night before routinely without issue, and then woke up the next morning and the engine would simply not start. I troubleshot everything I could think of and there were no fuel issues, no lanyard issues, all fuses were OK, but there was no spark to any of the plugs. With the electric start, the engine would turn over but simply not fire up. I am completely perplexed for such a new engine to suddenly have something go wrong and suspect it must be some kind of connection or electrical issue. And advice would be appreciated. Thank you.

  • Ted Roman

    I have a 2014 25HP efi. Runs great for about 45 minutes, shuts down and wouldn’t start for about an hour.Any ideas??

  • Sorry…. don’t really know anything about the bigger engines

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