DT30C Throttle Position Sensor Test

[cxgibson]

Hello! I recently purchased a 1992 DT30C. It runs very smoothly however it does not get to full power. I believe that the throttle position sensor may be faulty not allowing the timing to advance. I have removed the sensor however I cannot find anything that tells me how to actually test it. I did open it up and it appears to simply be a switch controlled by a cam that, when the throttle reaches a certain point, engages the switch. If anyone knows exactly how to test this I would appreciate it. Please note that I have not actually ran this motor and I am going by what the previous owner told me.I am just checking the easy stuff first. Even if this isn't a likely cause of the problem that the motor is having, I would like to know how to check the TPS. Thanks!!

[D'oh999]

There is No Such thing as a TPS sensor on a DT30. There is a Spark Advance, but it is Cam Driven.

Most likely, if you are having issues above 1/4 throttle it's in the Bowls of the Carburetors, They require a good Cleaning.

If it is a Stumble around 3000 RPM, then it might be a Low OIl/Coolant Temp malfunction.

[cxgibson]

There is No Such thing as a TPS sensor on a DT30. There is a Spark Advance, but it is Cam Driven.

Most likely, if you are having issues above 1/4 throttle it's in the Bowls of the Carburetors, They require a good Cleaning.

If it is a Stumble around 3000 RPM, then it might be a Low OIl/Coolant Temp malfunction.

Yes, it is simply a cam-driven switch, however I figured I would use the term "Throttle Position Sensor" because that is what every parts catalog that I have come across calls it, so I figured I would follow suit (and technically it is a sensor, in that it senses if the throttle has turned enough to change the state of the timing). I appreciate the advice, but the only thing I am interested in testing at this time is the correct operation of the Throttle Position Sensor/Switch. Any chance you know how I test this? It it as simple as testing continuity between the two leads on the plug? Does one ground out in one position and the other ground out in the other position? It has 3 wires. Two that go to the plug, and one that is grounded to the motor itself.

[D'oh999]

https://www.suzukimarine.com.au/know...entre/manuals/

Australia Website has Manuals.

[cxgibson]

https://www.suzukimarine.com.au/know...entre/manuals/

Australia Website has Manuals.

Thanks for the info, however they only go back a few years for my model (mine is a '92), and they don't mention how to test the sensor.

[D'oh999]

https://issuu.com/glsense/docs/suzuk...orkshop_manual

I still believe Spark Advance is handled mechanically, not electrically.

[cxgibson]

https://issuu.com/glsense/docs/suzuk...orkshop_manual

I still believe Spark Advance is handled mechanically, not electrically.

Although I appreciate the replies D'oh, I don't care if the spark is advanced by magic pixies at this point. Unless your next reply has something to do with testing the throttle position switch for normal operation, please keep it to yourself. I have no interest in testing anything else at all until I have determine that that switch is either good or bad. It was a pain to access, and I will not be moving on until I have either verified that it is OK or replaced it.

[Solarman]

There is a TPS mounted on the side of carb. Between the CPU and TPS you're supposed to attach a special jumper patch wire, this is used to measure the specific voltage at 3 or 4 positions of the throttle. Each of the positions of throttle varies the voltage from 0-5 volts. Accordingly, the CPU uses this voltage with the gear counting coil (CPU determines the rpms, by counting the teeth of the flywheel) to adjust the timing. The Suzuki service manual gives the voltages for each positon of the TPS, and the part number for the test wire. There is no adjusting the TPS.

There are several things I would check, before looking at the TPS. First I'd check compression, by the manual (this is an older 2 cycle).
Basically I'd look/clean the carb, the carb jets and needle valve seat, and see if fuel is restricted. If any problems with fuel pump, if the check-valves have broken small pieces may be lodged on the entrance to needle valve (restricting fuel flow at higher rpms), a common problem with older motors.

Good luck, post back on what you find out.

[cxgibson]

There is a TPS mounted on the side of carb. Between the CPU and TPS you're supposed to attach a special jumper patch wire, this is used to measure the specific voltage at 3 or 4 positions of the throttle. Each of the positions of throttle varies the voltage from 0-5 volts. Accordingly, the CPU uses this voltage with the gear counting coil (CPU determines the rpms, by counting the teeth of the flywheel) to adjust the timing. The Suzuki service manual gives the voltages for each positon of the TPS, and the part number for the test wire. There is no adjusting the TPS.

There are several things I would check, before looking at the TPS. First I'd check compression, by the manual (this is an older 2 cycle).
Basically I'd look/clean the carb, the carb jets and needle valve seat, and see if fuel is restricted. If any problems with fuel pump, if the check-valves have broken small pieces may be lodged on the entrance to needle valve (restricting fuel flow at higher rpms), a common problem with older motors.

Good luck, post back on what you find out.

There is absolutely nothing mechanically wrong with it, it has been thoroughly checked and tested mechanically. The TPS only has 2 positions as it is a cam actuated switch. At this point, the only think I am interested in testing is the TPS.