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2004 Sea Ray 380 MY Acceleration issues

Discussion in 'Sea Ray Yacht' started by j anderson, Jun 27, 2016.

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  1. j anderson

    j anderson New Member

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    Jun 27, 2016
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    Location:
    virginia beachh, va
    The vessel has about 700 engine hours. It has been very well maintained by certified mechanics for over the seven years I have owned it. The problem is that the port engine will not respond to the throttle (most of the time). It will go up to 1,000 rpms by moving the switch on the side of the helm station. It will run fine. It will increase RPMs by pushing the throttle forward and leaving it there for a few minutes. It will increase, but goes right back to idle. It does not cut off, and runs very smoothly at idle. The Cummins dealer has run a computer check and did not find anything wrong. They suggested I have the fuel injector pump inspected. I did have it inspected and they recommended it be rebuilt, and I did that. It was put back on, and the engine ran great for about 15 minutes. Then it reverted back to not responding to the throttle. We have moved the following sensors from the port to starboard engines, and nothing has solved the problem: Computer, crank shaft sensor, cam shaft sensor, throttle control sensor, engine control modules, oil pressure sensor, Changed fuel filters, Checked the electronic governor activator, and the rack positon sensor. Any suggestions? I have spent over $5,000 and no one seems to have a clue as to what to do next.
  2. Capt Ralph

    Capt Ralph Senior Member

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    8,401
    Location:
    Satsuma, FL
    Time to involve higher up support. Local shops are reluctant to do so for unknown reasons.
    I assume electronic controls and smart craft can bus i/o.
  3. j anderson

    j anderson New Member

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    Jun 27, 2016
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    Location:
    virginia beachh, va
    I do have electronic controls and smart craft. It is not showing any fault codes. I have the 480 hp 6cta 8.3 cummins engines. Do you suggest that I contact Sea Ray, or Cummins at a regional level?
  4. Capt Ralph

    Capt Ralph Senior Member

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    I luv my local Cummins shop but they have messed up on some Zeus issues that were later to find out; common known issues.
    I suspect you have fallen in the same rut.

    Give your post here a day or two for extra comments also.
    Maybe somebody has already had your symptoms.

    Your final support comes from Cummins, I'd bump it up there if nothing comes thru here.
  5. Capt J

    Capt J Senior Member

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    How are your fuel filters??? The bad fuel injector pump is making me think in that direction.
  6. j anderson

    j anderson New Member

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    Jun 27, 2016
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    Location:
    virginia beachh, va
    The fuel filters were changed in the spring along with oil and filter changes. We again changed the fuel filters, and they were still clean, and had no signs of water. When I run the engine up to 1000 rpms with the mechanical toggle switch it will run fine at that speed for as long as I want. It does not seem to be a fuel starvation problem. Today I spoke with the local Sea Ray dealer. They were not of any help. They just reminded me that the boat was not under warranty, and I should contact a diesel mechanic. Keep the suggestions coming. I do appreciate the help.
  7. Capt J

    Capt J Senior Member

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    Do you have 1 station or more than 1 station? It sounds like it's the gear/shifter control head to me. It doesn't seem mechanical from what you're describing.
  8. j anderson

    j anderson New Member

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    Location:
    virginia beachh, va
    It has one station, at the helm. We have switched the port and starboard shifters, and ran checks on the wiring to the engine. No electrical problems detected. When the shifters are switched, the starboard shifter does not work. The port engine still does not go above idle.
    The boat, by the way, is a 39' Sea Ray motor yacht. It has 6cta 8.3 Cummins engines.
  9. j anderson

    j anderson New Member

    Joined:
    Jun 27, 2016
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    Location:
    virginia beachh, va
    Today we started up the port engine and it ran like normal for 15 to 20 minutes. It ran at 1300 rpms and accelerated fine. Then it dropped back to idle, and would jump up and back to idle. No smoke from the exhaust. Cummins is coming back to again put a computer diagnostic check on it. We are still stumped as to why it will not keep running right above idle. I have another thing to ponder: I can set the engine speed by a toggle switch at up to 1000 rpms. When I set it, and try to speed up, it jumps up then goes back to the 1000 rpm setting. How strange is this? Help!