1975 302 188hp merc stalling problems

Discussion in 'Gas Engines' started by Spankdog77, Aug 10, 2011.

  1. Spankdog77
    Joined: Aug 2011
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    Location: Penetang ont canada

    Spankdog77 New Member

    Hey there. I'm a new boater this year. I purchased a 1975 cuddy with 302 merc 2barrel carb. It sat for the last 2 years. I've drained gas tank and put new fuel and stabilizer in it and replaced fuel/water separator. Here's the prob, it runs great for about 10-15 mins then will stall without warning. Sometimes it will fire right back up and sometimes it takes a bit of messing with the throttle to make it go. But when it does restart, it only lasts for a few seconds. I've already replaced coil pack, and was not the prob. Next I'm pulling carb to rebuild and replacing point and condenser. If this does not work, is there anything else I can try. Any feed back would be appreciated. Thanks!
     
  2. whitepointer23

    whitepointer23 Previous Member

    try replacing the ballast resistor. if its not that i would look for a fuel restriction or faulty fuel pump.
     
  3. Spankdog77
    Joined: Aug 2011
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    Location: Penetang ont canada

    Spankdog77 New Member

    Ok thanks for the input. I will definately look at that if the problem still continues after the carb rebuild
     
  4. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    depending what distributor you have in that engine, some had failing rotor buttons.
    I remember replacing quiet a few
    The ballast resistor is not a single unit on marine engines it is a wire in the loom, never seen a bad one?
     
  5. whitepointer23

    whitepointer23 Previous Member

    my 318's have seperate ballast resistors under the ignition module covers and my 302 mercruiser had a seperate one as well. my engines are pretty old though.
     
  6. Frosty

    Frosty Previous Member

    Runs well for 15 minutes at what,--- cruising speed or idle?

    Ballast resistor is for starting it will run without but the 10V coil will run on 12 V and will burn out eventually.
     
  7. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    Common shady tree mod to a Mercruiser was to install a automotive ballast resister (with new coil) to the end of the ballast wire ( the only key on power at the engine) because they didnt understand what they were doing now you have 2 ballasts inline..DOH
     
  8. whitepointer23

    whitepointer23 Previous Member

    i have had bad resistors in cars which run for a few minutes then cut out because they would over heat and cause to much resistance due to being stuffed. whether it is a seperate resistor like my chryslers have as standard or a resistor in the loom it can happen. i am not saying it is the problem just that it could be. maybe he has crap built up in the pump and fuel lines from sitting around. now you 2 can go on about how you have never heard of dirty fuel or clogged lines as well.
     
  9. Frosty

    Frosty Previous Member

    No I have heard of fuel blockages and I agree that would be a better way to go.

    However im not that good at diagnosis that I can say whats gone wrong when I don't even know it if stops when it runs for 15 minutes cold? at idle? or at 3000 rpm.

    Perhaps we should wait for this information before we go any further down the long list.
     
  10. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    exactly
     
  11. whitepointer23

    whitepointer23 Previous Member

    i wasn't trying to diagnose his problem, just threw in a couple of suggestions for him to try but once again i have been shot down in flames.
     
  12. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    I had stalling prob with mid 70's 302 just before it caught on fire. Fire was caused by faulty fuel pump dumping gasoline onto outside of engine. Diaphram cracked.
     
  13. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    It did that with a genuine pump??
     
  14. hoytedow
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    hoytedow Wood Butcher

    Yep. I was driving a Crown Vic on I-275 at Malfunction Junction. It lost power as I drifted onto the left shoulder. I parked it and watched it burn while I waited for the Fire Dept. I pulled the hood release but it was some kind of nylon cable which had already parted from the heat.
     

  15. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    ok so not a boat engine
    they have different pumps to prevent that happening
     
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