Engine stalls after 3-4 minutes of idling

mikefm58mikefm58 Posts: 265 Deckhand
I've got a 50 HP 2 stroke Merc that will stall after running at idle speeds, either in neutral or in a no-wake zone. It starts up fine, runs for 3-4 minutes, then sputters out and stalls. At wide open throttle it runs like a champ without any problems. If I pump the primer bulb when it starts to sputter, it comes back to life and runs fine for a few more minutes.

I've replaced the primer bulb, and now am thinking to replace the rest of the gas line. The gas is about a week old, and up until that gas tank refill I always had used ethanol free gas for the past couple of years. This one time I had to fill up at the gas station. I don't think the gas is bad since it runs fine at wide open throttle.

Any other thoughts or suggestions?

Replies

  • GrizGriz Palm Beach Gardens, FloridaPosts: 9,771 Admin
    Does the ball stay hard after you pump it?
    The early bird may get the worm, but the Second Mouse gets the cheese. SW

    :Griz
  • mikefm58mikefm58 Posts: 265 Deckhand
    Griz wrote: »
    Does the ball stay hard after you pump it?

    Before I replaced the bulb I had problems getting any kind of pressure in the bulb, so that's why I replaced that. I would have to pump it real fast and about 20 times to get any kind of pressure. Now with the new bulb, I get nice pressure in just a few pumps, but that pressure does seem to be gone when it stalls.
  • bmoodybmoody Posts: 967 Officer
    Sounds like fuel delivery, not fuel quality, to me. The fuel line is easy enough and not a bad thought. Also consider your fuel pump (assuming there is such a thing, I don't know that engine well) -- pumping the bulb could be overcoming the failing fuel pump.
  • steven_ucfsteven_ucf Posts: 30 Deckhand
    I had the same symptoms on my 94 40hp merc., then eventually it got worse, then I noticed when I primed it on my driveway it leaked fuel out of the exhaust as I was priming it.

    Took it in, they fixed the fuel pump,$75 dollars later - I was running like a champ.
  • RobpelotRobpelot Posts: 610 Officer
    Yeah fuel pump or Carbs...
  • mikefm58mikefm58 Posts: 265 Deckhand
    Thx for the replies. My problem is finding someone who can fix it by Friday as that's the last night of gator hunting season.
  • MelbourneMarkMelbourneMark Posts: 1,765 Captain
    I helped a buddy who had similar problems. It turned out to be a clogged fuel pickup tube.(Well the anti-siphon valve was the problem.) If you have a spare 6gal portable you can see if it is related to your fuel tank/hoses.
  • Aaron&NikkiAaron&Nikki Posts: 136 Officer
    I had the same problem with my old 90hp Merc and it turned out to the fuel pump. The diaphragms don't hold up to the ethanol fuel.

    That fuel pump is very easy to repair, took me about 30 minutes to do the first time I repaired it, and the new kits are only about $25.

    I'm not to far from you, send me a PM if you can't figure it out.
  • reel stamasreel stamas Posts: 6,153 Admiral
    See if it will run better on a portable 6 gal tank & different line
    If not I'd look at your fuel pump next
    There should be NO Commercial Fishing for any fish species considered 'Over-fished' , 'Undergoing Overfishing' or Subject to Recreational Seasons, Limits, or Closures... Game Fish Status IS the Answer !!!
  • Widespread PanicWidespread Panic Posts: 199 Deckhand
    I have a 60 Merc that did the same thing, new fuel hose, primer, fuel pump and carb cleaning, still the same. Ended up being a cracked float.
  • kanakakanaka Posts: 343 Deckhand
    How about this, keep pumping till hunting season is over, then replace the stuff you were talking about plus the quick disconnect and replace the hose clamps with fuel injection clamps.
    And DON'T use the cheap fuel line from the box auto stores. For some reason its R-7 they are still selling. Google it...
    [SIGPIC][/SIGPIC]
  • mikefm58mikefm58 Posts: 265 Deckhand
    kanaka wrote: »
    How about this, keep pumping till hunting season is over, then replace the stuff you were talking about plus the quick disconnect and replace the hose clamps with fuel injection clamps.
    And DON'T use the cheap fuel line from the box auto stores. For some reason its R-7 they are still selling. Google it...

    Yeah I thought of doing the pumping every few minutes when it sounds like it's getting ready to stall, but that will get old real quick, and be a huge distraction, not fun out there gator hunting. And problems like this usually just get worse, being out on the lake at 1 AM stranded would not be fun.
  • mikefm58mikefm58 Posts: 265 Deckhand
    My problem turned out to be some intake valve on the motor where the gas line connects to was sucking air. That and a new gas line is going to run me about $190 installed. Thanks to all who responded.
  • kanakakanaka Posts: 343 Deckhand
    Thanks for the update/solution, most folks leave us hanging. Was it the quick disconnect fitting or something else further down the line on the engine? Will help the rest of us troubleshooting.
    [SIGPIC][/SIGPIC]
  • kmagnusskmagnuss Posts: 2,875 Captain
    I had the same problem with my old 90hp Merc and it turned out to the fuel pump. The diaphragms don't hold up to the ethanol fuel.

    That fuel pump is very easy to repair, took me about 30 minutes to do the first time I repaired it, and the new kits are only about $25.

    I'm not to far from you, send me a PM if you can't figure it out.

    I had basically the same exact response. Same 90 hp engine. But it took me probably an hour to fix because I sit and stare at things to figure out why they work.
    Tarpon... everything else is just bait.
    Captain Keith Magnussen - Crooked Rod Charters
    Instagram is @crooked_rod_charters
  • kmagnusskmagnuss Posts: 2,875 Captain
    D'oh... just saw you got it fixed. Thanks for the update!
    Tarpon... everything else is just bait.
    Captain Keith Magnussen - Crooked Rod Charters
    Instagram is @crooked_rod_charters
Sign In or Register to comment.