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Davey Injection Pump?

Discussion in 'Compressors, Boosters & Blending Systems' started by Isaac-1, Apr 14, 2012.

  1. Isaac-1

    Isaac-1 Instructor, Scuba

    Does anyone know a good place that rebuilds injection pumps for a Hatz Z790 engine on a Davey 2MC1A? I tried to start mine up for the first time in about a year (spent the summer having health problems and recovering from major surgery last year) and it would not start or get fuel to the injectors, I think the plungers are stuck. Any documentation that you have that covers the injection pump would be nice too, the pdf scans I have are very blurry when it comes to looking at the pictures.

    thanks Ike
  2. totalloser

    totalloser New

    Oops. Didn't notice two cylinder engine at first.

    Looks like a cassette type injection pump. There will be a linkage that goes back to it from the governor, so careful when (if) you pull it out. The timing is set by the shim, and fueling is controlled by the governor link. Throttle control pulls on a spring that affects the governor operation.

    These pumps are still pretty simple. No timing issues. The only adjustment that is easy to get goofed up in a disassembly is cylinder balance. The fittings that come out to the lines probably have O rings, and Nitrile is a good idea if you pull them. There likely is a metal diaphragm that isolates the fuel from the oil and inside two pistons with metering barrels attached to a common link to control fueling.

    Usually these setups are pretty hard to kill. Most likely problem is fuel is not getting TO the pump. They, like most (all?) IP's are not tolerant of water in the fuel. Algae sometimes can create some messy nightmares, too. If it is getting fuel TO the pump, and you are planning on replacing it anyway, I'd try and get inside it. Might be able to free it up and clean it out.

    BEWARE of the little governor link. Usually there is a little clip that holds it on and it's pretty easy to drop into the case. I like to have a magnet probe hovering over it while removing it. If you pull the fittings below the injection lines, before pull the cassette assembly you will probably see immediately if there's been a water issue.
    Last edited: Apr 30, 2012
  3. Isaac-1

    Isaac-1 Instructor, Scuba

    Thanks, I have been side tracked with other projects the last week, plan to get back to this one soon

  4. Graeme Tolton

    Graeme Tolton Solo Diver

    # of Dives: 500 - 999
    Location: Orangeville, Ontario, Canada
    Take it to any bosch service center. Believe it or not, this pump is still serviced by parts and whole unit replacement.
    New pump on mine after i bought it last winter. Bad fuel ruined everuthing. Send me a pm if you need any more info.

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