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  1. #1

    GP1300 EFI tuning question

    I have 2 2004 GP1300s that I am repairing for someone. They were brought to me with frozen throttle shafts as they live on salt water 100% of the time here in S. FLorida. Anyway I was able to locate the bearings and seals from a local bearing shop and proceeded to complete the job with few problems and got the boats back together today for the lake test. While they ran pretty good I noticed a couple problems that I wanted to see if anyone could help with. One of the boats will not Idle and out of the water it sounds very lean. In the water it runs alright but when you stab the throttle it lean bogs for a second then takes off. This happens to about 3/4 throttle where after that it runs pretty clean all the way to wot and maxes out at apprx. 7000 RPM with speedo reading 69mph. The other boat seems the opposite as it runs rough at idle (feels rich) and while it is responsive it seems that when you floor it from any throttle position it reacts quickly but seems to hesitate while accelerating at approx 5700 RPM then continues on all the way to 7000.00. Also when I put the boat in the water it would only rev to 5000 for a few minutes then seemed to clear out although it wasn't "loaded up". I guess my question is how sensitive is the throttle position sensor on these. I did mark them when I removed them from the throttle bodies but I cannot guarantee that the throttle shafts are in exactly the same position as there was a lot of corrosion and I had to use some force to get them apart. ALso is there a syncing procedure for the butterfly valves other than doing by eye as I did. I don't have the software to hook it up but I can get access to it from a dealer buddy of mine. Over the weekend I plan on testing the TPS adjustment to see if it makes any difference. I have not come across anyone who has replaced the throttle shaft bearings on these so if anyone has done it then please let me know how it went. I am not 100% sure that there are not other problems but I did the normal checks including fuel pressure, spark, compression etc. Also if anyone is interested in doing the throttle shaft repair for themselves I can direct you to the suppliers for the shaft bearings and seals along with the butterfly screws.


  2. #2
    Moderator RX951's Avatar
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    welcome to the forum. Members WFO can Rossnemo may help you over that

  3. #3
    WATER WOODY's Avatar
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    Welcome to the forum.You throttle shafts are out of alignment,OR the TPS is not set right.Gimme a call and i can tell you how to check voltage to eliminate that problem.
    1-775-315-0222

  4. #4
    Hello Mutt, welcome to the forum.
    The first step is setting the tps.. It is very sensitive. Setting it at .79-.80 volts at idle is the spec. A voltmeter can be used instead of the yamaha software.
    Since you had the throttle bodies off the mounting rack then they are probably out of synch.
    I pour water through the throttle bodies and measure the flow to synch the blades at idle. Works very well.
    The tamper proof bolts that mount the throttle bodies to the throttle rack allow for some side to side play and will wreak havoc on your blade/synch adjustments if they were not leveled before they were assembled on the rack.

    I use an aluminum 4 foot level to align all 3 throttle bodies parallell before tightening those bolts.
    Try setting the tps first, if that doesnt work then give me a call.. Ross

  5. #5
    Thank you Rossnemo for the reply (and others). When i did the second set i placed the rack on the table of my milling machine while tightening the security bolts and that seemed to be better, I also found that there was a lot of movement permitted by these hole, sure would have made sense for Yamaha to put locating dowels in there. As for the voltage test could you please provide a little more info. what wires do I check and I assume that the connectore must be connected to the tps and I just tap into the wires but not sure. I was directed to this site because I was told you were the expert on this subject and I thank you for the reply.

  6. #6
    Bryan K's Avatar
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    Mutt, On the wiring harness under the front bucket there is a connction with a black wire with an orange stripe and a pink wire. Put a pin in each of those and hook it to your volt meter. You can also find these wires right on the ecu. As Ross said it should be .791-.80 for voltage. If that doesn't fix it definately call Ross!

  7. #7
    Happily Self-Employed WFO's Avatar
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    The spec is .80-.81. I read it thru the ECU with the YDS software.

    Personally I would not be poking holes in my wiring on a boat. You are setting yourself up for problems with your wiring down the road.

    If you must poke phucking holes in the wiring, coat the area with dielectric grease or silicone paste and seal the insulation with electrical tape.

    .02

  8. #8
    Thanks for the help everyone. I will give it a try tonight and see what happens. I hope that I can adjust the sensor while it is in place. I am getting tired of removing the exhaust on these.

  9. #9
    Happily Self-Employed WFO's Avatar
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    Quote Originally Posted by muttdog View Post
    Thanks for the help everyone. I will give it a try tonight and see what happens. I hope that I can adjust the sensor while it is in place. I am getting tired of removing the exhaust on these.
    You will have to drill an access hole in the stock air box to reach the TPS screws. After that you can use a nutdriver with the tamper proof torx bit and your hand should fit in there from the top.

  10. #10
    Thanks to everyone for their help but I am still having some issues. I changed the tps setting on both skis with no change, one ski does not idle and the other does not clear out on the top end. I put the throttle body from the one that won't clear out on the one that doesn't idle and now it idles so I know there is something I did wrong in rebuilding the throttle bodies. Does anyone out there have the procedure for setting these throttle bodies up from start to finish including amount of opening for each blade and setting up the idle set screws.

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