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  1. #1

    Default Detroit 653 Marine eng won't take a load

    I have two 653 Marine eng in my 42 foot boat. The starboard eng was just rebuilt. We placed the eng in and all the throttle cables were hooked up with full travel. The eng in neutral response is normal. But once a load is put on the eng I can only get 1000 RPM?
    Ie I put the boat in drive start advancing the throttles and both come up together till 1000 rpm, right eng goes no higher and the left one keeps going. I bring the left throttle back to match the right one at a 1000 rpm. And no matter how much I move the right throttle up, I only get 1000 rpm?
    please help

  2. #2
    Join Date
    Nov 2009
    Location
    temecula, ca., usa
    Posts
    2,614

    Default Re: Detroit 653 Marine eng won't take a load

    The problem is most likely with the governor. The limiting speed governors have a low speed spring that resists the action of the spinning weights for adjusting engine idle. Then, there is a high speed spring that comes in to play....at around 1,000-1,200 rpm interestingly enough....that resists the "push" of the spinning weights.

    The weights are used to push the governor back away from high speed operation by forcing the fuel control rods to pull the injector racks back toward the idle/no fuel position. The spring resists this "push" to keep the injectors delivering max fuel.

    Often times.....especially when the engine or governor gets worked on.....the high speed spring adjustment nut will back off, sometimes to the point that the engine loses most of it's power.

    The adjustment nut is kept locked in place by a back up "jam" nut. If the jam nut becomes or is left loose the high speed spring adjustment nut will invariably back off with significant loss of power as a result.

    That's what this sounds like has happened.

    EZ fix

    Good luck.
    Last edited by jgmo; 03-03-2017 at 02:38 PM.

  3. #3
    Join Date
    Apr 2016
    Location
    barnegat NJ
    Posts
    2,707

    Default Re: Detroit 653 Marine eng won't take a load

    Keep us posted Gregplandb

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