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Deere 777 power loss

Discussion in 'Mechanic and Repair' started by Remington351, May 1, 2013.

  1. Remington351

    Remington351 LawnSite Member
    Posts: 33

    I just bought a used 777 ztrak for residential use on my three acres. It has 2400hrs. The problem I'm having is a powerloss while cutting.

    If I'm cutting a run of approx. 250 feet when I start to mow I'm discharging the clippings from 8 to 10 feet, but by the end of the yard I can hear the mower deck slowing down and the clippings are only going 3-4 feet out of the chute. Once I make my turn, the deck speeds up again and the process repeats itself. I'm not experiencing any backfire, stumbling, or fuel starvation symptoms. Just a gradual power drop as evidenced by the shorter clippings discharge and noticeable drop in blade noise.

    Here's what I've done/know about the mower:
    FD750D liquid cool
    New Deere blades from the dealer
    Deck is level left to right and just over 3/8" pitch front to back.
    New 93 octane gas
    New fuel filter
    Greased deck spindles
    Motor idles smooth at fast, mid and low throttle position.
    New motor oil and filter
    New hydro oil and filter

    Tonight I checked the valve lash but did not have a chance to adjust it. Left side was .008 for intake and exhaust. Right side was .008 exhaust and ..010 intake. Could this be the source of my power loss or do I need to look elsewhere?

    Thanks for the help.

  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023


    Check the condition of your belts and tension, Glazed/stretched or out of adjustment is a possible cause.....
  3. Remington351

    Remington351 LawnSite Member
    Posts: 33

    Thanks Restro I'll give that a try.

    I did adjust the valves to .006 and cut an acre this evening. The valve adjustment seemed to help a little bit, but I was still experiencing some power loss.

    I'm used to cutting this lawn with my 17hp GT275. On the 275 I can distinctly hear when the governor is engaging while mowing, but I can't really notice the governor on the 777. Could this be part of my problem? :laugh:
  4. Remington351

    Remington351 LawnSite Member
    Posts: 33


    I put a tiny tach on the motor to see what it could tell me.

    High idle - 3620rpm
    Blades engaged but not mowing - 3510
    Mowing 2" of fescue level ground - 3420
    Mowing 2" of fescue uphill - 3050- 3350rpm depending on speed. The 3050 was at about 1/3 to maybe 1/2 of the control stick fwd range. To get 3350 uphill I was literally crawling at like 1mph.

    Does this sound like a governor issue? I could not find much searching here or google about the FD750D but I did find a post that mentioned coils dying under load. Could that be my problem?

    Any feedback is greatly appreciated!
  5. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    Not likely coils, When they fail you'd never get 3600 rpm. I wouldn't think governor issue with the rpm numbers you posted.

    I just re-read your first post, @2400 hrs you may want to check into having a leak-down test performed. Worn rings/cylinders will defiantly cause lack of power.......

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