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Suzuki DT 40, tiller, no start, confused

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  • Suzuki DT 40, tiller, no start, confused

    Hello SOF, I am brand new here. I have a DT40 that has no spark. I bought a Suzuki service manual for it, but there's no wiring diagrams. It says to check resistance to test the CDI and the stator coils, but the wire colors don't match up- There is supposed to be a White/black wire and a gray wire. I have pink, blue, green, black, white/red, blue/red, and a black ground wire. There are not 2 coils but one sealed CDI/coil together with 2 plug wires. The CDI says is a Mitsubishi?? The serial is 715020, which would make it a 1987. It has a low oil light indicator. it also has some wires in the harness not connected, but I'm guessing that's for the electric start options that I don't have. I read something about an NSI switch (neutral start Interlock) likely regarding the shifter lever, but I don't know where it is, nothing obvious. Also not sure how it is supposed to stop, there's no stop switch. Nothing looks like its missing. Is it a different year? Did somebody make some changes? all the wire connections match up with each other. Please help. The previous owner told me it hasn't been run for about 15 years, and was never run much. I can tell it was dropped once because the steering bracket is broken. I figure I should replace the impeller just because of age and 15 years of sitting in place. It has 120psi in both cylinders. I realize it could be anything- CDI, primary coil, secondary coil, pulser coil condenser coil, lighting coil, but how do I test without a wiring diagram that matches the wires I have? Very frustrating, but thanks much for any help you can give me.



  • #2
    Lee it might help if you could post a few pics of your motor. It also sounds like you might have the wrong manual for it? Maybe take a pic of serial number plate as well. The low oil may affect firing of this motor? This is a 2 stroke motor so you should premix fuel and oil to make sure oil is in the motor until you are certain the oil system is working properly.

    Post some pics back. Good luck.


    • #3
      Also Lee, your motor, if a dt40, 1987, should have an ignition coil #5, and a ignition sensor #6, and the CDI is your coil pack. The neutral interlock is a mechanical lever assy that should prevent you from being able to pull start the motor if it is in gear, or the throttle is too high. Your motor may also have a kill switch on the tiller, or front of motor for stopping motor.

      This is why pics of motor could help. Good luck.


      • #4
        Solarman, I saw your reply from another post of the same setup, something about Figure 13, #5 and #6, but on my figures from Brown's Point, it shows the coil box and a screw. Everything you say directly relates to what I've seen on the motor, but does that mean that coil pack #5 is/points to the CDI? I forgot about the thumb-stop potential. I'll check and take some pics when I get home. I also figured there's a low oil stop switch, but the reservoir is full. I should be able to bypass that for testing, as well as bypass the stop switch if I find it. The serial plate does not have any prefix or hyphen, just DT 40 and the six digits. I've never seen a factory manual with no wiring figures in it. I should be able to update you in a few hours. Thanks much.


        • #5
          Here's a few photos. Also I see the prefix now. And it does have a thumbstop on the tiller handle.
          Attached Files


          • #6
            Ok Lee, the ignition coil #5 , and ignition sensor #6 are part of the stator assy under the flywheel. The coil pack with the spark plug leads is your CDI unit (lower left pic). Your flywheel is covered up by the pull cord recoil assy (the top bracket assy with your starter cord wound up inside, used for starting motor). Do not disassemble the recoil assy - dangerous spring inside.

            The 04003 prefix is what i was looking for. You did not include a pic of the right / starboard side of motor (oil tank side, on yours), or the front of motor with tiller handle. This starboard side is generally where the shift linkages, and interlock linkages are located.

            I don't have your wiring diagram, but you might be able to Google "1987 suzuki dt40 wiring schematic", and get something close?

            Good luck with your search.


            • #7
              Do you have a Genuine Suzuki service manual or an aftermarket service manual? One would think a genuine Suzuki manual would have a wiring diagram, mine does.


              • #8
                Solarman, I thoughtt I could remove the recoil as a unit with the spring? I believe my manual is factory--here are some more pics...I was literally just about to remove the recoil. Let me know....thanks.
                Attached Files


                • #9
                  Yes, the recoil assy can be removed as an assy. But what do you hope to accomplish doing this?

                  Post back.


                  • #10
                    Yes, it appears to be the right manual. There should be some wiring schematic in your book that correlates to your motor, unless it is for different model of dt40? Look in the electrical section, see if they have multiple schematics?

                    As far as the wire colors go, is it possible the colors have faded do to age, or, is it possible someone has tried to repair the motor with different parts (because many parts are not available)?

                    In your pic of CDI/coil, #6627 is on the coil, I don't see any matching numbers for that coil? Checked above, and browns point.

                    You might try matching wire colors with parts pics of each part to what's on your motor?

                    Before taking a bunch of things apart, you might try sliding back the outer cover of groups of wires to seed if wire colors have faded?

                    Also, you will only get spark when pulling start cord. If you have a clip-on timing light, place foot of motor in large bucket, covering water pump (water level above water pump), can remove plugs, easier for pulling with no compression. Watch timing light, when pulling. If it flashes on either plug wire, you probably don't have a spark problem. Also, don't forget, most clip-on timing lights need a battery to work.

                    Good luck with your search. Post back on what you find out.


                    • #11
                      Solarman, last night I took the flywheel off. Am I supposed to have continuity between the white/red wire from the condenser coil and ground? The copper coil pack wire is black once it leaves the coil, then it goes into an outer cover and cone its to the white/red wire. Also I tested the stop switch, no continuity until I push the switch,seems ok. I also jumped the low oil, still no spark.lm thinking possibly condenser coil...Also everything under the flywheel looked like it was never touched, all fasteners have red marks and all line up, no Grey or white/black, checked under all covers. Will get you flywheel pics. Thanks



                      • #12
                        Sorry, cone its = connects to. I have Fat Finger Syndrome.


                        • #13
                          Solarman, here are some flywheel and stator photos. Also, how can I tell if its independent or simultaneus ignition? The stator/ignition coil part numbers are different. Thanks again. Lee
                          Attached Files


                          • #14
                            Also, is there any chance its a late '86 or early '88? Thanks.


                            • #15
                              Did you look through the manual for the wiring schematic? It might be in the electrical section, take a clear pic if possible, and post?

                              Your ignition sensor, (black coil) has the orange and green wire going into it. The ignition coil/condenser charging coil (white paper covered coil next to the ignition sensor coil), these are the two coils related to ignition spark/firing/timing. Timing/spark/firing is controlled by the metal plates on flywheel passing by the ignition charging coil (this charges the coil pack with plug wires/CDI - Condenser Discharge Ignition coil pack), the igniton sensor causes the CDI to discharge when the small metal plate on the flywheel passes the ignition sensor.

                              The lighting coil, or batt charging coil is the other coil on the stator assy. This coil creates AC voltage, converted to DC voltage at the rectifier/regulator for the needed voltage to run the electrical needs of the motor, and charge a batt if one is connected.

                              In your manual there is a section that gives information to ohm test each of these items listed, it should give you the good/acceptable ohms for each coil, with the flywheel on, or off. The ignition sensor may need (?) to be tested with the flywheel on properly, and possibly where the metal plate is in front of the sensor?

                              Good luck, post back on what you find out.