Welcome Guest - Sign Up today
Welcome Guest - Sign Up today



Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

Thank you all in advance for doing your part in helping iboats run a smooth ship.

Additional forum rules linked below.
See more
See less

New to Boating and my 2004 Tohatsu 90HP TLDI will not start. Please Help!

  • Filter
  • Time
  • Show
Clear All
new posts

  • New to Boating and my 2004 Tohatsu 90HP TLDI will not start. Please Help!

    I just bought a used boat about a month ago. It is a 2003 McKee Craft 172 Backwater and it has a 2004 Tohatsu 90 hp TLDI. First time I took it out it started right up and ran well, I was able to shut it off and restart with no issues. Daughter had to use the restroom so I went to a dock turned the engine off and when she got back in I was able to restart it and slowly made my way back out to deeper water and when I tried to give it some throttle it died and I had a hard time getting it restarted but luckily I was able to get it started and back off the water. Did some research and thought it was likely old gas so I replaced the fuel/water separator and dumped a can of Seafoam in the tank and ran it from home with muffs. Stalled one time in the driveway but figured that was because I didn't prefill the water/fuel separator with fuel but once restarted I could not get it to repeat the issue so I figured problem solved. I have taken it out 2 times since this and it has started on the first try and ran flawlessly for the entire day both times. After taking it out last Monday, I brought it home and started it and ran fresh water through it in the driveway for about 15 minutes on idle. No issues! So I load the wife and kids up this past Sunday drive 45 minutes to the boat ramp, put the boat in the water and I can not get it to start. It was acting like the battery was low. When I turn the key it makes the beep sound and then I try to turn it to start the starter cranks the flywheel but seems to not be cranking with enough power. I unplugged the battery and plugged to another battery I had with me and it does the same thing. Another boater saw me having issues and offered his freshly charged battery and it did the same. The GPS/depth finder and electric trim work fine but the engine will not start. I have been removing the key and kill switch when I park the boat so it has me wondering if the kill switch could have broken and the motor thinks it is removed. The other strange thing it is doing is the beeping sound comes back when I turn the key to start. So what I mean is it beeps for a couple of second when turned to on (this is normal) and when it stops I attempt to turn to start and the engine tries but with little power to start and the beeping returns. Could I have a bad kill switch or ignition switch? I tried turning the key to on and cranking the flywheel manually but it didn't do anything like it was not sending anything to the spark plugs. Pulled and cleaned all 3 spark plugs but cant get the boat to do anything. My local marina cant look at it for 3 weeks and I really want to get it out a couple more times before winter. Any suggestions on what to check, what to do?

  • #2
    If it is cranking slowly, you may have a bad connection; possibly a bad ground. TLDI motors aren't really shade tree mechanic friendly, so best to see a dealer, unless you want to get the service manual, put it in diag mode, and learn how they work.
    Buffalo NY USA


    • #3
      Running the self diagnostics I discovered the engine only has about 100 hours on it, so this makes it even more surprising that I am having an issue already. There were a couple other fault codes so I plan to wire brush the terminals and get a very tight fit, clear the fault codes and attempt to start the engine again. With luck it will start and the issue will have only been terminals (not feeling confident on that at all), is not I will run the diagnostics again to see what fault codes come up. I also bought a multimeter and plan to check the continuity on the kill switch to make sure it is working. Now I see why people say owning a boat is like digging a hole and throwing money into it. ARGH!!


      • #4
        Is it really possible that the slightest amount of rust on the battery connectors could have been causing my issue? I tested the continuity of the kill switch and determined it was fine. I had 12.5 volts at the battery and at the starter solenoid when i turned the key to on so I didn't think it was a connection issue but figured I would start with the simplist thing and pulled the battery out wire brushed the terminals and connectors then reconnected and tightened everything snuggly. I did that and cleared all existing fault codes then gave it a try. Didn't start the first attempt so I checked to see if it fired new codes and it didn't so I gave it a 2nd try and it fired right up! Turned it off and on multiple times with no issues.
        Almost wish I had tried again before cleaning the terminals and connectors just so I knew that was really the issue. Just seems too insignificant as the terminal and connectors looked pretty clean before I did anything and I had the boat out less than a week before having issues and it ran and started fine then. Hopefully my problem is fixed but I am not 100% convinced.


        • #5
          Electrical connectors, grounds are always overlooked as being fine to the eye, but not working right electrically speaking. It's good from time to time to disconnect all electrical conectors, grounds to clean, polish, shine them all for all electrical/electronical parts to work spot on and last longer.

          Happy Boating

          Sea Rider 320, 380 Sibs, 450 Rib, 2 Strokes Tohatsu 5,18 & 30 HP Proud Smokers


          • #6
            Yes, it's common.


            • #7
              Sign up today
              I would be checking the electrical connections on the engine and the solenoid, check the earth connector on your starter and make sure everything is tight underneath the plastic flywheel cover.
              The MD90B needs to have a strong starter to crank the engine fast enough to generate compressed air.
              Use caution when poking around because the ecu is easily damaged.
              The best investment I made for my MD90B was to get a service manual, I paid for a hard copy before I found a free digital copy, you can download it for free, let me know if you want the link.
              Last edited by Anthony555079; October 8th, 2017, 10:16 PM.