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  1. #1

    Default mercury 90 hp won't crank after it warms up.

    Hello,

    New on site and could really use some help.

    Motor starts right up, runs for about 5 minutes and dies and then won't crank. New battery, Key switch, solenoid, and connections. Any ideas would be greatly appreciated !

    Thank you.

  2. #2

    Default Re: mercury 90 hp won't crank after it warms up.

    Just to clarify, won't crank (as in starter won't spin) or won't start (but the starter will spin)?

  3. #3

    Default Re: mercury 90 hp won't crank after it warms up.

    Also, what year motor and 2 or 4 stroke?

    I am assuming by you are saying that the starter won't engage because it looks like you have replaced much of the electrical system.

    Do you hear the solenoid click when you turn the key? If you don't then you need to get your volt meter out and see if you are getting 12+ volts to the solenoid.

    If the solenoid is clicking then you need to check the starter itself. You may need to take it apart and check the brushes and wiring for corrosion. Also, sometimes the battery cables themselves get green corrosion deep in the wires and just cleaning the connectors wont fix it. If thats the case you can clip the wire back until the green is gone and crimp some new connections on it and try again.

  4. #4

    Default Re: mercury 90 hp won't crank after it warms up.

    Thank you for responding. 2004 2 stroke. NO click..nothing. When i push the key in for the choke it clicks but other than that..nothing. When it's cold it cranks like a champ!! I am stumped. Also, new battery and all cables and ends are clean.

  5. #5

    Default Re: mercury 90 hp won't crank after it warms up.

    Well,

    As a general rule, most electrical systems will show their first sign of failure when hot.
    The best clue that we have at this point is that your solenoid is not engaging when the key is being turned. Your FIRST test at this point should be to see if the positive wire coming from the key harness to the solenoid is getting 12v when you turn the key (when the issue is present). Let us know if you are getting 12v there.

    I am assuming that you changed all the electrical out because of this issue??

  6. #6

    Default Re: mercury 90 hp won't crank after it warms up.

    [QUOTE=rotus623;564755]Well,

    As a general rule, most electrical systems will show their first sign of failure when hot.
    The best clue that we have at this point is that your solenoid is not engaging when the key is being turned. Your FIRST test at this point should be to see if the positive wire coming from the key harness to the solenoid is getting 12v when you turn the key (when the issue is present). Let us know if you are getting 12v there.

    I am assuming that you changed all the electrical out because of this issue??

    I have not replaced all the wiring yet. I'm going to get my electrician neighbor to help me with checking the voltage.
    I will let you know what the findings are as soon as I get him a 12 pack to do it. LOL. I will be learning to use a voltmeter now.
    Thank you for all your help so far, I am grateful.

  7. #7

    Default Re: mercury 90 hp won't crank after it warms up.

    Ok so as you look at the solenoid, there is a yellow wire with a red stripe on it. That is the +12v wire that signals the solenoid to close allowing the main power to jump it and activate the starter motor. You will want to put the red lead of the volt meter on that wire or lug and black onto the ground wire (or bare block). When the key is turned you will want to see if you get 12v to the wire. My guess is you will NOT get 12v there when you turn the key (when the problem duplicates.)

    If you aren't getting 12v there, I believe that you have a bad neutral safety switch in your control box. That is the switch that keeps the motor from starting while in gear. Sometimes you can push the red lever and jiggle the throttle lever and all will be well. That is a good way to see if it is a loose connection.

    Start there and let me know how it goes. If it is a bad neutral safety switch they are pretty easy to get to and replace. Let me get the serial number of your motor and I will try and send you a diagram of it.

  8. #8

    Default Re: mercury 90 hp won't crank after it warms up.

    Oh and on a sidenote, I dont like waiting for others to be able to do what I got to do. I made a set of test leads with gator clamps so that I can run them to the motor and still get my multimeter hooked up to them to read it while turning the key. Just set the meter to either 10 or 20 scale on VDC (voltage direct current) and see if the voltage is there.

  9. #9

    Default Re: mercury 90 hp won't crank after it warms up.

    Try wiggling the throttle lever could be a bad neutral safety switch.

  10. #10

    Default Re: mercury 90 hp won't crank after it warms up.

    O.K. I am back after some medical emergencies and have replaced the cdm modules (3 of them) because 2 "mechanics" told me that would be the problem..same thing. It will start and run until it gets warm..GO to restart..nothing. The choke will engage and click but it wont turn over. I have checked all connections and everything is tight. I HAVE NOT checked the voltage at the solenoid that was suggested as I just now read that. Just an update..NEw ignition swith..new solenoid..new cdm modules. I have jiggled the handle and taken it in and out of gear and moved kill switch up and down and made sure it stayed in correct position.battery is new and charged. I will check the voltage this weekend weather permitting and post findings...Once again thank you so much for your help. Chops

  11. #11
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    15,195

    Default Re: mercury 90 hp won't crank after it warms up.

    Try jumping the starter directly from a good battery and see what happens.

    Jeff

  12. #12

    Default Re: mercury 90 hp won't crank after it warms up.

    O.K. I put a jumper wire from the ignition switch to the solenoid and WOOHOO!!! Let it run for a while and restarted SEVERAL times!!! That tell me it's the neutral safety switch per some helpful people. Wish I would've tried that first.LOL..Oh well, Lots of new parts. It's sputtering and backfiring every so often and spits out a bunch of blue smoke when revved..Hoping it just needs to run awhile and clean out the carbs and old gas. We will see. THANK YOU to all who helped me !! Any extra suggestions on the blue smoke and backfiring would be appreciated!

  13. #13
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    15,195

    Default Re: mercury 90 hp won't crank after it warms up.

    "Take her out and run the crap out if her." Got that advice 60 years ago from a Merc mechanic and it's still good.

    Jeff

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