Evo starts reving uncontrollably

Discussion in 'Engine, Fuel and Exhaust' started by keye, Sep 27, 2010.

  1. keye

    keye Member

    I have 97 RoadKing, thanks to this site I have found a tappet block oil leak which I plan on fixing when The scoot is parked for the winter, now a new problem has come up....like I said its a 97 RK with Fuel Injection, basically completley stock except chrome accessories, I go for a 30 to 40 KM ride and the bike starts reving high, I have no tack but would say that easily the revs double if not more than at idle, cracking the throutle does nothin, once this reving starts it stays till at least a coupe hours of shutdown, than starting her up she goes back to normal with the familiar Harley idle, I had this problem Last spring when the weather was cool, than it stopped and ran perfectly all season, now up here in canada the weather is starting to cool down and now the revs have come back, this has happened twice the last week, and again the weather is at low 50's....I see there is a senser at the linkage at the motor.....putting finger pressure on the linkage at this senser, the revs lower but releasing pressure and the revs start back up....to put it in prespective, today at a stop lite it lookes as if I was at a dragstrip and reving the heck out of the bike.....it just does not look cewl...any help would be appreciated, I do not want to park the bike yet......thanx

    BUBBIE Well-Known Member

    Sounds like you Found Your problem... If loose or worn out??

    Is it easy to get a new sensor and install??

    I would replace it IF not a lot of $$$..

  3. HDDon

    HDDon Experienced Member Contributor Retired Moderators

    Do you know what sensor it is? Would the TPS or IAS sensor cause this? Do you have a manual that you can look at to determine which sensor seems to be causing the problem? If I'm not mistaken you have the first itteration of the HD FI and I don't have access to the manual.


    Go to self help to see how to retrieve Morrelli codes and what they are.
    Last edited by a moderator: Sep 27, 2010
  4. keye

    keye Member

    removed the breather and breather plate...everything open to veiw......my clymers manual not showing this unit....it sits dead center on back of throtle body, it is wrapped with a rubber boot with a wide wire harness plugging ito it and it regulates the throtle control...starting the bike up it sinks in for a split second and than pushes outwards against the throtle assemby, just like the old auto chokes on the autos....again applying finger pressure against the senser the bike goes to a nice idle, releasing the pressure the idle revs up high, itsbeen 3 hours and by rites the idle should have been back to normal as with the last times this happened, but now she still screams in idle....I would hate to guess and take this unit off and take her in for a replacement if this might not be the problem....I cannot even give you a name again as my manual does not show this senser......man this (EDIT) big time

    Please read this...
    A Friendly Reminder - Harley Davidson Community
    Last edited by a moderator: Sep 27, 2010
  5. Jack Klarich

    Jack Klarich Guest

  6. keye

    keye Member

    just started it up and now she idles normally again......tried checkin the codes but unfortunitly way over my head...gonna take her for a run tomorrow...if it screws up again will bite the bullet and take her to the dealer....not what I want to do but might be a whole lot cheaper than tearing out every senser I see and replacing them, a dude today told me that it is an oxygen senser, but I get the feelin he was just grasping at anything.....it just seems to happen in the cooler weather
  7. Jack Klarich

    Jack Klarich Guest

    See post 5,may help you diagnose it and save you some cash:D
  8. voganni

    voganni Member

    i have the same bike, same problem in cold weather. My theory is the temp sensor, which controls the idle speed plunger (thing you're putting your finger on) is not seeing a warmed up engine, cuz it's too cold. It was about 30° today and the bike was idling about 2k when I pulled into the gas station. Mine will idle down after about a minute. Rest of my ride it was fine. I'm gonna read up more on it in my service manual. It seems to be going to cold idle speed. Bill
  9. lorne

    lorne Senior Member

    had the same problem on those other bikes... turned out i didn't route the cable properly. it was a easy fix