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  1. #1
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    Default 1978 Black Max Mercury 175HP

    I have a 1978 Black Max Mercury 175HP and it wont get above 2500 rpms. The engine runs great in netural and reverse, but when we try to take off the motor starts to kick. The engine also kept wanting to stall out In idle. If anyone knows how to fix this problem or has delt with this situation please respond.

  2. #2

    Default Re: 1978 Black Max Mercury 175HP

    Steve, I am having the same problem with my 1985 175 Mercury. The mechanics at the lake removed all the carbs, cleaned and replace. Thought it was a fuel problem. Motor still will not do over 2000 rpm. The said they called Mercury and Mercury told them most likely is the high stator. I am waiting to get it back in the shop and see if that helps. Good luck.

  3. #3
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    Default Re: 1978 Black Max Mercury 175HP

    someone also mentioned that I may have spun a hub on the prop. We also mentioned bad gas as well.

  4. #4
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    Default Re: 1978 Black Max Mercury 175HP

    Not the prop, if the hub spun the engine would rev but the boat would not accelerate.

    Most probably the high speed windings in the stator failed.

    HOWEVER< since there is NO RETURN on expensive electrical parts you want to test it properly before you start throwing money into it.

    CDIElectronics.com wrote the book, available for FREE download.

    Their Ignition Troubleshooting Guide will identify your ignition system, and walk you thru the tests required to make the diagnosis and save you major time and money.

    The DVA Meter required will cost you far less than the mechanic charges at the shop you have your boat in.

  5. #5
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    Default Re: 1978 Black Max Mercury 175HP

    I agree bad Stator happende on my 1988 max same way. You should change the rectifier and inspect the rev limiter they tend to burn up when this happens. All three were bad on mine. All easy to replace.

  6. #6
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    Default Re: 1978 Black Max Mercury 175HP

    Yes just got back from the marina and that's what they told me it would have to be a bad stator. Has anyone changed one before. If so how easy is it to change.

  7. #7
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    Default Re: 1978 Black Max Mercury 175HP

    You need the mercury threaded puller they are all over the internet this is the hardest part mine was a pain it is just a cylinder that screws into the top of your flywheel in the center. the stator itself is connected to the rectifier and the control box easy to see just match the colors. Then screw the wheel back on and your done. Some people cheat and take the flyweel bolts off I suppose this is not good cause it changes your top dead center alignment when you time your motor.

  8. #8
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    Default Re: 1978 Black Max Mercury 175HP

    Well before I spend money at the marina with the whole stator thing, we were talking to some people about what was going on and they told us to try some seafoam. Has anyone ever tried this? I poured it into the gas tank and tested the engine out in the drive way it sounded a lot better, I noticed it's not smoking anymore as well. The engine also was able to get up over 4000 rpms. Were going to take it to the lake Saturday morning to see if it helped if it don't then I'll take the next step. I do want to thank everybody on iboats for their help on this, it means a lot.

  9. #9
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    Default Re: 1978 Black Max Mercury 175HP

    If your stator is bad it could be intermitten like mine was runs good then it strands you out in the water I would change it the windings on it get bad over time and your motor is 32 years old. Just a thought.

  10. #10
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    Default Re: 1978 Black Max Mercury 175HP

    Reving the motor in Neutral does NOT place enough load on the ignition to test the high speed windings in the stator.

    Either test IN gear ON the water at WOT or use the DVA Meter.

    The DVA Meter is a LOT easier than launching the boat, finding out it STILL doesn't run right, pulling it out and back home having wasted a lot of your day.

    DVA test can be DONE in 15 minutes. Then you will KNOW.

  11. #11
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    Default Re: 1978 Black Max Mercury 175HP

    We just got back from the lake the other day and we cruised arond in it for a little bit and all we could do was 45 mph and, and all of a sudden it just took off we were then doing about 74. I'm thinking that sea foam helped out. It ran great the rest of the day at the lake. Shankforce you could be right the high stator could be intermitting right now.

  12. #12
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    Default Re: 1978 Black Max Mercury 175HP

    We took it out the other day and it was doing the same thing not wanting to go above 2,000 rpms. Took it to the marina and they said it was the switchbox. They repaired that and were taking it back to the lake tomorrow. Shankforce you were right it was intermitting.

  13. #13
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    Default Re: 1978 Black Max Mercury 175HP

    good read keep us updated, that motor hauls !

  14. #14
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    Default Re: 1978 Black Max Mercury 175HP

    Did they change both the switch boxes they are mated together if I were you I would double check after they are done make sure all the colors match up and are tight with no frayed wires.

  15. #15
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    Default Re: 1978 Black Max Mercury 175HP

    Alright will do thank you shankforce

  16. #16
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    Default Re: 1978 Black Max Mercury 175HP

    Quote Originally Posted by CharlieB View Post

    DVA Meter is a LOT easier than launching the boat, finding out it STILL doesn't run right, pulling it out and back home having wasted a lot of your day.

    DVA test can be DONE in 15 minutes. Then you will KNOW.
    Great thread, any recommendations on a DVA brand/model?

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