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Results 1 to 9 of 9
  1. #1
    Join Date
    Jun 2009
    Location
    New Plymouth,Taranaki,New Zealand
    Posts
    291

    Default Compression test on 150hp merc EFI

    Hi,need advice on doing a compession check on a 1993 merc 150hp v6 efi. Do i need to disable the efi? Will winding it over with kill switch activated protect the ign coil ,and disable efi? How to achieve full throttle,is it by pushing button on gear lever to disconnect it from gear selector cable? Any advice greatly appreciated. Looking to buy this boat this weekend

  2. #2
    Join Date
    Jun 2013
    Location
    Duluth Mn
    Posts
    1,290

    Default Re: Compression test on 150hp merc EFI

    Wow, New Zealand. Been to Australia, stayed over a month while travelling around in a tiny rented RV, great place. They drove on the wrong side of the road there, I got plenty "thumbs up", so a guess my driving was pretty good? Eh?
    Do the compression test with all plugs out and just wedge open throttle valve part way to ensure good intake air. To avoid any feed into electrical system trigger a direct power to STARTER side of the solenoid when you need to crank. That way all power will be isolated to only spin the starter. It cannot get back across the solenoid into the "HOT SIDE". Configure a jumper in a way so as not to arc at the starter, or at the battery, but touching 2 cables together in your hands in order to crank. You will, therefore, get no ignition or fuel anywhere and you won't have to disconnect any wires. Of course, the key will be left in the off position.
    Last edited by timguy; 02-17-2019 at 03:54 PM.

  3. #3
    Join Date
    Jun 2009
    Location
    New Plymouth,Taranaki,New Zealand
    Posts
    291

    Default Re: Compression test on 150hp merc EFI

    Thank you for that.I dont think these have a kill switch that I can operate to kill power to coils etc

  4. #4
    Join Date
    Nov 2011
    Location
    tennessee
    Posts
    3,111

    Default Re: Compression test on 150hp merc EFI

    No,no...just :1) pull all the plugs, 2) pull kill tether, 3) install gauge and crank with key. Kill tether kills ignition and thats where ECU gets it signal to fire injectors. No spark no injector....Compression spec 110-135psi
    Last edited by faztbullet; 02-17-2019 at 09:26 PM.
    Pappys Sales and Service
    Owner and Factory Certified Technician
    Former racer KDBA (Kentucky Drag Boat Association)

  5. #5
    Join Date
    Jun 2013
    Location
    Duluth Mn
    Posts
    1,290

    Default Re: Compression test on 150hp merc EFI

    This is the common way with 2 people. I usually work alone. Your right Pappy, thanks.

  6. #6
    Join Date
    Jun 2009
    Location
    New Plymouth,Taranaki,New Zealand
    Posts
    291

    Default Re: Compression test on 150hp merc EFI

    thank you

  7. #7
    Join Date
    Aug 2017
    Location
    South Africa
    Posts
    175

    Default Re: Compression test on 150hp merc EFI

    Compression should be almost equal over all 6 cyl.

  8. #8
    Join Date
    Jun 2009
    Location
    New Plymouth,Taranaki,New Zealand
    Posts
    291

    Default Re: Compression test on 150hp merc EFI

    Guy wouldnt give me his adress,so bought another boat,with 115hp 2001 johnson,290 hrs ,v4 sounds very good. Yes,great place in NZ,sunny,cheap,good society etc,apart from some Australian visitors

  9. #9
    Join Date
    Jun 2013
    Location
    Duluth Mn
    Posts
    1,290

    Default Re: Compression test on 150hp merc EFI

    Sorry, Budgie, you are in our prayers. We are afraid each day when we start the tv.

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