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Yanmar 2GM20F throttle is extremely stiff

Discussion in 'Engines and Propulsion' started by SVEnchantress, May 3, 2015. Add this thread to a FAQ

  1. SVEnchantress


    Joined Sep 16, 2014
    21 posts, 1 likes
    Pearson P303
    US Titusville
    Ever since we've had our boat, the throttle has been hard to move -- it has gotten progressively worse. I assumed (incorrectly it seems) that it was the cable.

    When I detach the cable, I actually find that the throttle on the engine is super hard to move.

    Anyone had this issue before ? What was the remediation for problem ?

    Any suggestion will help :D

    Woodyapex likes this.
  2. woodster


    Joined Sep 15, 2009
    6,240 posts, 262 likes
    S2 9.2a
    US Fairhope Al
    if your cable is working freely then you may have a problem in the injector pump as the fuel advance is in that part of the engine and if that is the case you may need to rebuild your injector pump will have to take that to a diesel repair shop and have it rebuilt ...i think kloudie may have some more in out but for now that all i have i think i remember him saying some thing about this one time but we will have to wait for his input

  3. SVEnchantress


    Joined Sep 16, 2014
    21 posts, 1 likes
    Pearson P303
    US Titusville
    If it were due to the injector pump, would it be because the fuel rack is not moving correctly ?

    I thought the engine stop also manipulated the fuel rack (to cut off fuel), and our is working fine ?

  4. Benny17441


    Joined May 24, 2004
    5,384 posts, 308 likes
    CC 30
    US South Florida
    Start with the basics, make sure the speed control lever is not bent or damaged. Since the problem has been evident since you have had the boat insure that the bracket and linkage parts are properly positioned. Check and see if the shaft itself rolls freely or if the stiffness is being transmitted from inside the timing gear case. The speed control lever attaches to the governor system via an internal linkage which has a secondary lever that controls the high pressure injector pump. If everything checks out externally I would remove the pump and check on the free operation of the lever without the pump. Replacement of any governor components will entail removing the timing gear case. Start at the basics and good luck.

  5. kloudie1


    Joined Nov 6, 2006
    7,845 posts, 518 likes
    Hunter 34
    US Mandeville Louisiana
    2 GMF Governor

    Enchantress, I have attached drawings of the governor for your engine. Basically, the lever that the cable is hooked to (Regulator Handle) rotates in the housing and is sealed with an o-ring. It is the only external part of this discussion. It is attached to the regulator lever and pulls on two springs which pulls on the governor control lever which ultimately pulls the governor lever that controls the fuel rack of the injection pump. The engine stop lever works directly on the fuel control lever. If the stop cable works smoothly and easily, then the problem probably is in the regulator lever attachment binding on the case, or the lever shaft o-rings binding on the shaft. where they are in the case. You can try to get some light oil (maybe wd-40 to start) on the "regulator handle" shaft where it goes into the case but that is about all you can do without going into the gear case. That requires pulling the injection pump, so it may be good to get a Yanmar mechanic to do that one if light oil doesn't free it up some. Caution on that one is that if the "throttle" sticks open be ready to pull the kill knob to control it.

    EDIT Note that if the engine holds a good constant speed in gear and out, then the governor is controlling the fuel rack well and that is probably not sticking/binding. The sticking/binding would be in the case or inside at the interface with the other levers.

    Attached Files:

    Last edited: May 4, 2015
  6. SVEnchantress


    Joined Sep 16, 2014
    21 posts, 1 likes
    Pearson P303
    US Titusville
    Will check that all out.

    Yes, the engine holds speed perfectly, and the engine stop works great too.

    Unfortunately, will not be able to get to the boat for a couple of weeks, but will post back my findings.


  7. Woodyapex


    Joined Aug 29, 2015
    22 posts, 0 likes
    catalina 30
    US big pine key
    Thank god for google and you Kloudie1
    Just setting off on a trip after the boats been stood a couple of month and the I could not put revs on . I actually thought I'd snapped the cable . Any how a quick search on google and I read your post and the arm ( like you mentioned is rubbing . So I've fixed it ;) but I'd still like to know why it just started rubbing . Why would it get worse ?
    Is the casing expanding ?

  8. SVEnchantress


    Joined Sep 16, 2014
    21 posts, 1 likes
    Pearson P303
    US Titusville
    Not resurrecting a dead thread, but just putting closure on this in case any else Google's it.

    Due to illness, it has taken me this long to check out the issue and it was indeed due to rust forming between the throttle shaft and the governor cover.

    Fix was to use liberal amounts of PB Blaster on the area, wire brush it, and remove the cover and wire brush it as well. A bridge of oxidation had formed where the cover went around the throttle shaft. I also lubricated everything with prior to re-assembly.

    One thing the manual does not show is that the cover has a gasket. I was able to make a new one using some gasket paper from the local auto parts store.

    Thanks for the help!

  9. markwbird


    Joined Nov 26, 2012
    818 posts, 152 likes
    Hunter 34
    US Berkeley
    I had this same problem with my 3GMF. It was rust on the throttle lever on the engine. This was caused by a leaky raw water hose clamp just above the throttle lever dripping seawater down onto it. I suspect you may have a similar issue.

  10. SVEnchantress


    Joined Sep 16, 2014
    21 posts, 1 likes
    Pearson P303
    US Titusville
    Yes, but I had already fixed the leak when I rebuilt the whole raw water cooling system

  11. markwbird


    Joined Nov 26, 2012
    818 posts, 152 likes
    Hunter 34
    US Berkeley
    Well, then I don't know.

  12. Mark Maulden

    Mark Maulden

    Joined Jan 25, 2011
    1,581 posts, 128 likes
    S2 11.0A
    US Anacortes, WA
    I had an issue with a stuck throttle on my 37 yr old volvo. Lost a little sleep over that one...Sprayed some Liquid Wrench lubricant on it right where it enters the case. Use the red tube and stick it right where it goes onto the case to get some pressure to it. Freed it right up. Do it twice/yr as a preventive.

  13. runninglts


    Joined May 2, 2017
    1 posts, 0 likes
    C&C Landfall 35
    US Fort Myers
    Huge thanks Kloudie1 ... had the very same problem with my Yanmar 3HM ... as others mentioned I thought at first it was the cable, cable clamp, or a broken component where cable terminates in the steering pedestal. After disconnecting the cable from the engine I realized the cable was fine but regulator lever wouldn't budge. I started freak a bit at that point thinking that I would have to disassemble casing to repair something internally which would have been a huge PITA and possibly expensive.

    But after reading this thread, I removed the lever, delivered a good amount of penetrant directly on to the shaft entering the case, let it sit for 5 hours or so, then exercised the lever by hand and slowly it began to move then completely freed it self!

    My guess is that a slow drip from a leak around my engine panel right above the regulator lever caused the shaft to rust after a month of non use. I since rebuilt the panel so no more water leaks on to the engine ... and I won't ever again be neglecting the periodic spray of light oil over all metal surfaces!

  14. pateco


    Joined Aug 12, 2014
    1,997 posts, 517 likes
    Hunter 31 (1983)
    US Pompano Beach FL
    I have the opposite issue. My throttle moves freely, but will not stay above half throttle. it just slowly moves back down. I know there is a friction clamp on the cable in my lazarette, but was wondering how to know how much to tighten this clamp to resolve this issue. I don't want to damage my throttle cable. For now I have been using a velcro strap to hold the throttle lever in place on the pedestal, but I would like to fix it correctly.

  15. justsomeguy


    Joined Feb 20, 2011
    6,244 posts, 766 likes
    Island Packet 35
    US Tucson, AZ/San Carlos, MX
    Incrementally, @pateco , incrementally.

    pateco likes this.
  16. kappykaplan


    Joined May 1, 2011
    768 posts, 116 likes
    Pearson 37
    US Lusby MD

    pateco likes this.
  17. Tally Ho

    Tally Ho

    Joined Jan 7, 2011
    983 posts, 124 likes
    Oday 322
    US East Chicago, IN
    The throttle on my O’Day 322 would ease off and I stuck a zip tie on the pedestal to hold it at my cruising RPM. Then I removed the compass from the Edson pedestal to get access to the throttle friction bolt. Very easy fix...and cleaned and lubed the steering chain while I was in there.

    Not sure what setup you have, but suggest you open the pedestal and give it a look.


  18. NYSail


    Joined Jan 6, 2006
    1,705 posts, 75 likes
    Beneteau 423
    US Mt. Sinai, NY
    Tighten 1/8 turn and see what happens and stop tightening when it stays where you want it.

    pateco likes this.

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