150 yamaha surging

Discussion in 'Outboard Maintenance' started by jeff_erickson, Jul 18, 2011.

  1. jeff_erickson

    jeff_erickson I Love microskiff.com!

    8
    0
    76
    I have a 150 hp yamaha v max carbed and it surges @ high speed bad, it also now starts like a efi with no choking necessary. I see alot of gas film on the water. I did a compression test with 110 across the board. A a fuel pump pressure of 4.5 lbs on both.
     
  2. Brett

    Brett > PRO STAFF <

    Fuel feed would be my first guess.
    Checked your plugs to see if you're running rich?
     

  3. twitch

    twitch Well-Known Member

    90
    0
    331
    I'd check the fuel pumps again. Unbolt them from the block and pump the primer, if any fuel comes out of the engine side of the pump the diaphragms are shot. A bad FP diaphragm can make you run rich at idle and lean on the top end, just as you described. [smiley=2cents.gif]
     
  4. jeff_erickson

    jeff_erickson I Love microskiff.com!

    8
    0
    76
    Thanks, I think I will rebuild both pumps to be on the safe side. Cheap fix for a 2005 engine
     
  5. jeff_erickson

    jeff_erickson I Love microskiff.com!

    8
    0
    76
    Do you think ethanol might have caused the trouble?
     
  6. DuckNut

    DuckNut Brandon, FL

    4,544
    414
    1,938
    Ethanol is not the root of all engine problems. Most likely it is the years of use that simply deteriorated the seals and gaskets.
     
  7. twitch

    twitch Well-Known Member

    90
    0
    331
    If you are running ethanol I'm sure it contributed, if in fact your fuel pumps were the source of your problems. ETOH is hard on rubber parts.
     
  8. cutrunner

    cutrunner Cert. Yamaha technician

    Ok. If your fuel pump diaphrams are white, they are mylar and most likely your problem, the updated ones are black and made of neoprene. Or.. Another syptom of your problems is a stuck float or a "sink" (a float with a hole in it that doesnt, well float lol)
     
  9. jeff_erickson

    jeff_erickson I Love microskiff.com!

    8
    0
    76
    I replaced both fuel pumps and it runs like new! Thanks
     
  10. twitch

    twitch Well-Known Member

    90
    0
    331
    Glad ya got it fixed.
     
Loading...
Similar Threads Forum Date
'07 Gordon 18' Waterman Tunnel w/ 70 Yamaha & Ramlin Trailer Microskiffs For Sale Today at 9:47 AM
For Sale: Yamaha Prop Boating, Fishing and Marine Products for Sale Wednesday at 6:13 PM
New 2007 Yamaha F25 Atlas microjacker Outboard Maintenance Oct 13, 2017
2015 Yamaha F 70 with SS power tech prop Boating, Fishing and Marine Products for Sale Oct 13, 2017
Yamaha 90 (2 stroke) 20" Boating, Fishing and Marine Products for Sale Oct 12, 2017