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  • #1

    Throttle Positioning Sensor

    1994 225TXRS 2 stroke

    I checked the TPS and from the readings in the 3.00 to 5.00 range I determined it was bad and ordered a new one.

    Well I installed the new one and get the same readings as adjusting it with the two phillips screws does not help.

    So I took it off and tried adjusting it by simply turning it with my fingers. I got the reading I wanted, 0.49 as the manual calls for a reading between 0.47 and 0.51.

    I put two marks where the pin that goes through the rod is supposed to be. Now hopefully the pics show y'all the problem I am having with setting the TPS correctly.

    Front view of bracket that was on boat when I bought it 3 years ago.


    Side view showing the plastic piece with the notch that the TPS pops onto to.


    Here is the problem. When I place the TPS in a position to where the pin can snap into the notch on the plastic piece, you can see how far off the screw holes are to bolt the TPS down.


    Side view shows where the pin on the TPS is supposed to pop into the notch on the plastic piece. With it being so far off, the is no way to adjust the TPS to the specs the manual asks for when it is bolted properly in place.


    Now I remember I had a problem two years ago when I rebuilt my carbs and tried to sync them according to the manual. I couldn't get the correct readings on the sensor. The motor ran and runs, but does act up a lot due to this. So this time while syncing the carbs, I decided to get the TPS set properly.

    But now I am wondering at some point before I got the motor that someone might have put the wrong bracket on it?

    I am going to try and secure it in the position that the reading on the fluke meter shows to be correct. Then go out and run it to see.

    Does anyone know if it is even possible to put a wrong bracket on the motor?

    Or what could possibly cause the readings to be so far out of specs that would cause the screw holes to not align up properly?
    Tags: None
  • #2
    UPDATE:

    Here is a bracket picture I found on online that says it is for the '94 to '95 engine and it has three bolt down places as opposed to my two. SO I'm now wondering if it put the holes on the sensor in the proper places to get the right adjustment values for the sensor?



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    • #3
      looks like the plastic coupler between the throttle shaft and the TPS is mangled.

      Comment

      • #4
        Surprised no one replied, maybe to tricky of an issue? lol! But no, the plastic coupler is good, just nicked up from messing with it to much.

        Update though: I fabricated a plate that bolted to the stock bracket above and put the TPS in a position to be able to adjust it according tot he manual, .47 to .51.

        The engine does not like that setting and actually, nothing in that range when I turn the TPS would make the engine happy.

        I then removed the plate and just went back to the original position with the TPS and dialed it in at 3.67 which makes the engine somewhat happy. It still tries to bog down when I jam on the throttle in the driveway. Though easing into the throttle does not cause it to bog down.

        So I am wondering why my TPS has to be set so far out of range to make the engine happy?

        Since the computer sets the timing, not sure which way to go at this point except a mechanic.

        Any ideas or has anyone had or seen this issue?

        Comment

        • #5
          cause you don't understand what the TPS does.
          that and I believe your on the wrong wires.
          orange to black is the 5v reference, pink to black s the TPS output to the ecm.

          tis a dirt simple system that has been about since about 1990.

          Comment

          • #6
            Care to elaborate a little more please?

            Because this is what I know, whether it is right or wrong, so please lead me in the right direction.

            Back the idle speed screw out until the throttle plate next to the screw is completely closed.

            Connect the positive test lead of my Fluke Meter to the pink wire on the TPS.

            Connect the negative test lead to the orange wire.

            The correct meter reading is 0.49-0.51 volts at closed throttle.

            Adjust sensor until correct reading is attained.

            The sensor I had would only adjust between the readings of 3.00 to 5.00 ranges. So I ordered a new one and got the same results.

            Then I got the same results with the new one. Though when I remove the sensor from the bracket and adjust it with my fingers, I can get the correct ranges from 0.49 to 0.51, but then it does not line up properly with the plastic piece on the carb.

            The reason I made the plate to mount to the bracket to get the correct readings, which the engine did not like. So today I ran it out fishing all day at a reading of 3.67 which I attained by listening to the engine.

            It ran good, though it was a bit sluggish on take off and bogged down a bit at WOT.

            So this is where I am at and it is lost.

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            • #7
              Something I just didn't know about was the reference from the computer. So I just checked it on the Fluke Meter and got these readings:

              Black to Orange is 5v
              Black to Pink is .005v
              Orange to Pink is 4.89v

              Comment

              • #8
                from what Rodbolt wrote I would think pink to black is what you should be monitoring while adjusting, but what do I know

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                • #9
                  I would remove the home made bracket and install the TPS correctly and try again.
                  are you back probing or do you have the TPS test harness.

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                  • #10
                    I removed the plate Friday and tried to set the TPS. The plate is off of it right now.

                    I do not have the harness, but read to use paper clips from a post you made in 2011. SO I guess that is what you are referring to as back probing? Re-reading the post, you said the engine has to be running. So what numbers will I look for then?

                    I'll start to look and see where I can order one though.
                    Last edited by FirePro911; 07-21-2013, 05:36 PM.

                    Comment

                    • #11
                      Ok, here is a short video of what I am doing to try and set the right TPS setting. Am I doing something wrong here?

                      TPS Adjustment.avi - YouTube

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                      • #12
                        engine does not have to be running to set the TPS.
                        however a small amount of electronics knowledge is a must.
                        I don't keep service manuals here at the house.
                        Ill try to get more information tonight.

                        Comment

                        • #13
                          Got It! (hopefully)

                          After much internet searching, just when I was about to get to the end of the internet, I found this thread from 2005.

                          250 TPS Adjustment?

                          Originally posted by boats.net View Post
                          Are you sure you are using the pink and orange wire on TPS voltage. The orange and red wire is the input voltage to TPS and 3.7 to 4.9 would be ok between orange and red. The pink and orange are the output wires the voltage should increase when open throttle on carbs by hand, if no voltage increase then TPS is bad.
                          Originally posted by Salty Dog View Post
                          The sensor has red, pink and orange and the motor has black, pink and orange. I was getting the 3.7 to 4.9 from the pink and orange wires. Should I try a different set of wires? Thanks.
                          Originally posted by boats.net View Post
                          Yes, open throttle and watch voltage it should increase in voltage when throttle as the opens if not then try the other wires.
                          Originally posted by Salty Dog View Post
                          OK, I just set the TPS
                          So apparently on his motor and now mine, we have to adjust the TPS between the pink and red wires, as I went home at lunch and set my TPS properly.

                          My orange and pink wires were giving me the input voltage to the TPS. Once I checked between the pink and red wires, I was able to get the voltage output when I open the throttle, then once throttle was closed, the TPS setting settled back almost within specks of .47 to .51.

                          I tried to dial the TPS in precisely, but as rodbolt17 said in an earlier post, the plastic coupler is mangled. So when I tapped on it or the bracket, the settings would move around. This also prevented the settings to settle back to the .51 I had the TPS at. It would stop out of specs around .520 to .530 at times. So I am ordering a new plastic coupler.

                          So I wonder how many folks have had this issue and like me, went out and purchased a new TPS without needing one?

                          Once I put the boat back in the water and it runs good, I'll put the other TPS on eBay and hopefully get some of my money back.

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