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f 115 warm starting problem

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  • f 115 warm starting problem

    engine has had the following done 1) fuel system totally redone 2) new voltage reg 3) new battery, cables ,ends 4) new tach . engine starts and runs fine when cold or cool . run it to operating temp and turn off for say 10/15 minutes it cranks but does not start. let it cool down a few minutes with cowling off then starts and runs fine . I had the tach also replaced and it does not read consistently. I have been told that Yamaha tech support says it could be ecu but everything I read says they rarely go bad .Now mechanic wants to start replacing stator etc. under the flywheel to see if that's the problem, but we put computer on engine ran up the creek and it says 12.5 to 13.4 so it must be charging. it seems I am replacing one thing at a time with no one knowing the cause . anyone out their with an answer ???? model f115 4 stroke , f115TXRA #704927
    Last edited by DALE WITHERS; 09-21-2014, 12:24 PM. Reason: REQUEST FOR MODEL #

  • #2
    Can you please post a year and model #, it's sometimes needed..

    12.4 is NOT charging, your running off the battery. A fully charged battery is 12.8 volts or so.. Wether its the voltage regulator or stator, more testing needs to be done.
    Scott
    1997 Angler 204 CC, 2006 F150 TXR

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    • #3
      F115 warm starting problem

      Originally posted by townsendsfjr1300 View Post
      can you please post a year and model #, it's sometimes needed..

      12.4 is not charging, your running off the battery. A fully charged battery is 12.8 volts or so.. Wether its the voltage regulator or stator, more testing needs to be done.
      voltage reg replaced . If stator not working( producing proper voltage right) would that effect tach not reading properly ? Tach is brand new. And the starting problem when warm/or hot ?

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      • #4
        tach signal is ECU generated.
        you have already begun the splatter gun testing.
        expensive.
        find a tech with at LEAST Yamaha electrical and 4 stroke systems certs on the wall.

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        • #5
          f115 warm starting problem

          I am still having warm/hot or actually operating temperature starting problems. I have read many posts about other models having similar problems and it seems that it is a vapor lock ??? motor starts right up cold and runs great. I had fuel system taken apart ,injectors sent out and cleaned , just put a ECU on this motor which solved the TACH reading issue . thank you rodbolt17 , so is this a common problem for this year motor ?? f 115 TXRA IT MUST BE FUEL RELATED AS RUNS GREAT OTHERWISE . JUST WILL NOT START AFTER SHUT OFF WHEN MOTOR SITS FOR LIKE 10/15 MINUTES. IT DOES START UP AFTER IT COOLS DOWN . DOES THE PART THAT HAS FUEL AND WATER GOING THRU IT NEED REPLACED OR CAN IT BE TESTED OR CLEANED ??

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          • #6
            RB, could the fuel cooler be clogged up ?



            Part #12, I believe its a 2002 model;
            2002 F115TXRA Yamaha Outboard FUEL INJECTION NOZZLE Diagram and Parts

            You should be able to disconnect the lines/unit and make sure it clear and water flows thru it..


            Last edited by TownsendsFJR1300; 10-05-2014, 08:17 PM.
            Scott
            1997 Angler 204 CC, 2006 F150 TXR

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            • #7
              Just to add, if the cooler is indeed clear, check to see if (with Muffs on), your getting water TO the cooler and that the coolant keeps flowing (the rest of the hoses flow water beyond the cooler)..

              This is the water flow for my F150, likely similar to yours;

              Scott
              1997 Angler 204 CC, 2006 F150 TXR

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              • #8
                if your tell tale stream works, the cooler is ok.
                does the ISC valve rest at shutdown?

                that's the rattle noise you should hear when you turn off the motor.

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                • #9
                  f115 warm start problem

                  Thank you for the responses to my issue. To answer rodbolt 17 , yes I checked and upon turning motor off there is a " rattle sound " like a pump or something shutting down or resetting . as far as the fuel cooler the water flow from pisser is strong as I have also replaced the impellor, thermostat,etc.

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                  • #10
                    ??

                    Hi Dale.
                    Did you work out what was wrong? I have the same problem.
                    Thanks

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                    • #11
                      paging Rodbolt

                      I have a 2005 115 hp mercury fourstroke. Knowing I have the same power head, I have read most of Rodolts posts regarding the f115 hot restart issue/excessively rich.

                      When the engine won't restart after a hard run, Rodbolt suggests starting with the throttle advanced. It always works. I also have found if I cut the engine at 2000 rpm, I get get reliable hot restarts. I just don't want my wife and kids to have to do this.

                      Rodbolt has diagnosed this on other sites as needing a vapor shut off valve and recovery tank. I have never been able to find that kit.
                      Can I just disconnect the VST vent to the air box? Is it dangerous to vent into the cowling? Is there a charcoal canister kit for my engine?

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                      • #12
                        posting on an old thread is not the way to do this.

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                        • #13
                          Originally posted by egstasea View Post
                          I have a 2005 115 hp mercury fourstroke. Knowing I have the same power head, I have read most of Rodolts posts regarding the f115 hot restart issue/excessively rich.

                          When the engine won't restart after a hard run, Rodbolt suggests starting with the throttle advanced. It always works. I also have found if I cut the engine at 2000 rpm, I get get reliable hot restarts. I just don't want my wife and kids to have to do this.

                          Rodbolt has diagnosed this on other sites as needing a vapor shut off valve and recovery tank. I have never been able to find that kit.
                          Can I just disconnect the VST vent to the air box? Is it dangerous to vent into the cowling? Is there a charcoal canister kit for my engine?
                          I have vented mine (F150) to atmosphere and have had no issues for two years now.. Hot starts are much better for me at least .Don't know about 115 ?

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