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Map sensor pressure suzuki df 115

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  • #16

    Hello. Have now done some research on the engine and taken some pictures of sds. Was a bit difficult since sds disconnected all the time. Rpm was uneven. The rectifier seems ok after the measurements. Did not test extra grounding on the high pressure pump since the boat is at sea and bad weather. Tried to read out info on O2 sensor but no info came out. As for the temperature, this increased to 78 . Started it again and then it went down to 56


    • #19

      Some engine updates. Has done as redlowrey recommended by connecting power directly to the high pressure pump. The pressure on the pump was 39psi with original cabling and 48psi with new supply. Now the sds became stable and stays connected all the time. Have checked all wires as well as negative but find no fault on the wiring. Measured with a multimeter in the power plug. Positive on plug and negative is 14.67v. If I measured on negative in plug and negative on motor it is 0.92mv dc.Do not know if this matters. Have also measured rectifiers and found that the diodes are ok. Also checked the coils which according to the manual should be between 1.9-2.5 but when measured both showed about 3.8ohm. Could this be an ecu fault? This with the cooling is probably something that is moving in the cooling system since it comes and goes so here the powerhead has to go off.
      I have also tested a new battery and new cables.Attach some photos.
      Last edited by Freddy jakob; 05-24-2022, 11:57 AM.


      • #21

        Some troubleshooting today with sds. Has connected negative directly from ecu to negative on engine block since these went into a common negative circuit. Even now there are high peaks and sds falling out. All cables are good. When I connect my own power supply to the fuel pump everything is normal. Also has ohm o2 sensor and measured voltage and shows 14.6dc at start and varies from 14.6 to 7.8dc and when the engine is hot the voltage is 2.7dc. The manual says 3v so it is 0.3 v too little. IAC is 8 OHM. Then the high pressure pump, stator and ecm remain as a possible source of error. It becomes a bit expensive to only buy new parts when you do not quite find the fault. Another thing is that the tps only shows 75 at full opening but it probably has nothing to do with the fuel pump to do.


        • #22

          o2 sensor before engine gets hot


          • #23

            pictures of sds logging
            Attached Files


            • #24

              Thought to ohm tps to see if it is dead spot but it does not say anything about this procedure in the manual. I know the values ​​come up on sds but some say the most correct is to ohm. Some electronics can be damaged with a 9v multimeter. Has anyone tried ohm tps?


              • #25
                Originally posted by Freddy jakob View Post
                It looks like you are on the heater circuit of the 02 not the signal the way the multimeter is fluctuating because that circuit is duty cycled, what is the noise I can hear. Mate if you are trying to chase an electrical noise problem you are never going to find it using a digital multimeter. You need to be using an oscilloscope, and if you don't no how to use one all you are going to do is spend a lot of money swapping out parts.

                The primary coil winding readings are high check them again on a cold day, that is the sought of resistance you would have on an old system that had a distributor and points that would limit the primary current to about 4 amps. Today's systems run between 7 and 15 amps, check the secondary as well, if the resistance between the plug leads for each coil are very low it will produce electrical noise.

                You have got to understand when you supplied your fuel pump with power and a ground the pump will run at 100% because the computer is not controlling the ground, and how are you checking the pump pressure because 48psi is too high the pressure reg should have blown off just under 40 psi, are you teeing into the rail or dead heading straight of the pump.

                When ever I am chasing problems I will use an oscilloscope more than a multimeter, there is just no comparison especially for noise or an event that happens quick like checking the action of your throttle position switch for drop outs you can use your multimeter but nowhere as accurate.

                Put up a screen shot of how they are telling you how to check the 02 sensor. Tell me what that noise is when you are testing the 02 sensor.


                • #26

                  Hi and thanks for the feedback Redlowrey. True as you say with osolyscope. I'll get one. The sound is bubbling since the engine is in a big "bucket". When I measured the coils on the primary side, it was 3.8ohm and 12 air temperature and cold engine. The secondary side was the measurements right after the book. Should be between 1.9-2.5ohm at 20 according to the manual. Either the manometer is wrong or there is some inertia in the fuel regulator. The manual states 42 psi max. Attaches 1 picture of measurement on pin 36 for o2. this must be 0.2 or less. Thank you very much for the feedback. It helps me a lot


                  • #28
                    To check the secondary readings connect your meter to the spark plug ends on each coil they should between 16 and 30 kohms, that is thousand ohms do, you understand that this is a waste spark ignition system meaning when the coil fires it will deliver spark to two cyls at the same time, meaning 1 and 4 . 2 and 3 one cyl will be on compression, say no 1 and its companion no 4 on overlap. you haven't shown what the secondary resistance is.

                    It would not matter whether you had the pump connected to an external power and ground or from the original supply the pressure should not have varied, the pressure reg inside the vst should have blown off at 40 psi so how you got 48 psi is strange. You were on the heater circuit on the 02 sensor. The 02 sensor needs an external heater to get it up to temperature before it can work,, when it gets hot enough it will start to cycle between .1 and .9 of a volt, when the computer see's the voltage low it will increase the pulse width on the injectors and then the voltage will go high .9, when the computer see's this it will decrease the pulse with on the injectors and it will go low.

                    While you are in cruise this process will be continue cycling the voltage to keep the air fuel ratio at 14.7 to one, if you run the engine at 2000rpm and watch the live data on your sds you will see the small changes in the injector pulse width


                    • #29
                      I meant to add, have you got another meter to check those primary's if they are 3.8 ohms that is high for for an electronic ignition system, I never check because if I am checking an ignition system I will be looking at the coil output on an oscilloscope and I will be able to see the coils output. I will actually check one and see what I come up with.