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Yamaha 150 4 stroke (2006)

The MidgeThe Midge Posts: 501 Officer
Looked through a couple pages of this pages threads but didn’t see anything similar........
After oil (and lower unit) change water/fuel sep replacement I took the boat out this weekend and after about 15 minutes the boat would sputter and stall out at idle. Ran smooth as ever when throttled up but shortly after going out of gear it would do it again. Only way it would crank back up was to pump the ball a few times and it would crank fine and off we go. Nothing sounded off when running, no alarms,  no indication of an issue other than the stalling at idle??? Any ideas before I get knee deep in this. Anyone experienced this before??
Looked around the Internet and saw about 50 different directions to start from but figured I would ask here first. 
Thanks! D


  • Tony RomaTony Roma Posts: 996 Officer
    How old is the primer bulb? Might be collapsing pinching off fuel flow, start cheap and work your way up. Crank it on muffs in the driveway or lift, when it starts bogging out squeeze the bulb. Could be anything from water in the fuel to missing injector. How longs the boat been sitting. Keep us posted, to many of these threads get no resolution. 
  • MelbourneMarkMelbourneMark Posts: 2,710 Captain
    My old 2stroke did something similar and it ended up being the fuel pump going out.  It would run fine as long as someone squeezed the bulb. 

    So, it sounds like a fuel related issue, but there are numerous possible problems:
    clogged anti-siphon valve
    crack in bulb allowing too much air in
    clogged fuel filters (how many internal on the outboard?)
    clogged pickup tube in tank
    water in gas tank

    I always tell folks to try a portable gas tank and that will help narrow down possible problems.   Also, when is the last time you have changed the fuel water separator?
  • Tony RomaTony Roma Posts: 996 Officer
    OP says he just changed oil , water separator , and lower unit oil. 
  • Soda PopinskiSoda Popinski GrovelandPosts: 15,118 AG
    That primer bulb collapsing had me chasing filters, vents, carbs, losing my mind.   First thing i do now is change that bulb.  
    Yesterday's memories are not today's reality
  • The MidgeThe Midge Posts: 501 Officer
    I'll check the primer bulb this Friday for sure. Would the bulb collapsing only happen when I put the motor in neutral? That is when it was happening. 

  • Soda PopinskiSoda Popinski GrovelandPosts: 15,118 AG
    shouldn't collapse at all.   
    Yesterday's memories are not today's reality
  • The MidgeThe Midge Posts: 501 Officer
    I don't recall any variance in it when I was pumping it to get it cranked back up but I will replace it anyway due to the age of it. 
  • Tony RomaTony Roma Posts: 996 Officer
    Like I said, start cheap, buy 2 bulbs and keep the extra on the boat. 
  • The MidgeThe Midge Posts: 501 Officer
    10-4. Thanks for the advice. Will report back on Saturday what I find. 
  • polliwogpolliwog Posts: 341 Deckhand
    You can eliminate a fuel delivery issue with a separate portable tank.  I did this with my 90HP . Separate tank ,engine ran fine through the speed levels.  It was the fuel bulb at fault.  I did happen to have a 5gal tank for a 5hp trolling motor I used.
  • The MidgeThe Midge Posts: 501 Officer
    10-4. Thank you for the advice. 
  • quest450quest450 Posts: 82 Deckhand
    last month had identical issue, 2008 F150
    fuel tank was 1/3 full, changed water-fuel separator and filled up with fresh fuel, no problems since, keeping my fingers crossed
  • MelbourneMarkMelbourneMark Posts: 2,710 Captain
    I had fuel issues a few years back.  I ended up buying a $20 12volt fuel pump off amazon.  I put long wires and alligator clamps on it.  I hooked up the pump/battery 15 feet away from the boat.   I bought a new fuel/water separator with the clear bowl on it. 
    I hooked up the fuel hoses to the gas line and then to the fuel fill. basically a big loop from the tank, thru the filter/pump, and back into the tank. 

    I let the pump run for 2 hours and drained the bowl a few times of the water.  I did this on and off for a few days and likely got a few gallons of water/dirty fuel out of the tank. 

    I now do not use regular gas and only non-ethanol gas.  I think I got some bad gas at a marina as well or left the cap off when it rained outside. 

    Since then not many problems.  I still use the clear bowl and drain it after a few hours of running. 
  • The MidgeThe Midge Posts: 501 Officer
    Update....... finally made it to the boat storage to address the situation. Started with the primer bulb no issue, looked good. Checked the water fuel separator for any leaks or sign of anything, looked good. Pulled the cowling off to check the fuel filter on the motor and there it was!! I guess when I checked it during my maintenance I didn’t screw the **** thing back on tight enough. It needed about another full rotation to completely seal it. Done deal with the help of you guys and I didn’t have to spend a dime!!! Thanks everyone for chiming in with advice!!! 
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