Page 1 of 2 12 LastLast
Results 1 to 20 of 22

Thread: Diagnose My Yamaha

  1. #1
    Join Date
    Sep 2007
    Location
    Boone, NC
    Posts
    6,230

    Default Diagnose My Yamaha

    Early 2000’s twin HPDI Yamahas 150 hp

    Ran flawless last year.

    Completely forgot to treat fuel over winter, it sat in the tank, last time it was used was September.

    Wanted to take the boat out a couple weeks ago, hooked engines to muffs, they fired right up with no issue what so ever. Take it to the lake, cruise around for at least 4 hours, not a single issue at all. I have not put new gas in the boat, it’s running on last year’s fuel. Before taking the boat out of the water, I stopped by the marina and put 10 gallons of e free in each tank.

    I picked up a dock slip last weekend, took boat out and docked it, didn’t drive it much, but it idled for at least an hour, no issues at all, ran as it should.

    I took it out this afternoon. Boat is running great, we went sub 5 mph for at least 20 minutes, throttled it up and cruised on plane for 10 or so minutes, starboard engine bogs down, I still have the port engine. I had my wife and 2 of my kids on the boat and sunset was a couple hours away, so I started heading back to the dock. Now the port engine bogs down. I lost pressure in bulbs, crank it back up and port engine comes back with starboard still sputtering and dying out. Port engine is going in and out, low rpm’s, seems to not be getting fuel. It goes in and out a few times, I’ll pump bulb, it goes again. About halfway back it goes out, neither engine will start. I go back and pump both bulbs and pressure builds, port comes back to full power with no bog, I bump key on starboard and now it’s back full throttle/rpm, boat is running perfect again.

    I make it into the no wake zone, starboard is good, port bogs down right when I get to the slip after running fine for 300 yards of no wake. I dock it and start seeing what I can and can’t do. Starboard is running like a top, bump the key and it starts with no hesitation. I can get port to run, but I have to turn key and automatically put it in gear, it dies unless you give it gas though.

    I’ve ordered new fuel water separators as well as the fuel filters that go under the cowling. Planning on seafoam and maybe a fuel treatment. My guess is a filter/water/fuel issue since both motors were affected the same way.

    Anything else I need to change out?


    *Im pretty sure I got a bad batch of gas last year. One of the engines (can’t remember which) bogged down. I got it going again, and had 0 issues again after at least 7 trips and likely 15+ hours on the water.
    Last edited by huntinghagen#12; 04-05-2023 at 10:19 PM.

  2. #2
    Join Date
    Mar 2002
    Location
    7 Lakes NC
    Posts
    80

    Default

    Plugs could be fouled up.
    Gulf

  3. #3
    Join Date
    Jan 2011
    Posts
    185

    Default

    I would replace fuel line as well. Bulb also. Fuel line could be colasped
    Hancock 70 Yamaha

  4. #4
    Join Date
    Dec 2011
    Posts
    26

    Default

    Confirm it’s a fuel delivery issue by running an external fuel tank straight to each motor. My guess bad bulb then check fuel line.

  5. #5
    Join Date
    Sep 2009
    Posts
    864

    Default

    Def fuel, start simple but I’d check VST. You have junk in your fuel, just a matter of where it is. Hpdi’s had issues with the VST, worth a google search.

  6. #6
    Join Date
    Nov 2013
    Posts
    4,992

    Default

    Clean the VSTs and the medium pressure fuel filters just after them. Its the silver one about the size of a shot glass. Make sure you are running 10 micron filters and plan on buying a case until you clear the b as d fuel out.

    Losing bulb pressure is usually one of two things... Weak/failing fuel pump or introducing air into the line somehow.
    Last edited by FishSticker; 04-06-2023 at 06:24 AM.

  7. #7
    Join Date
    Aug 2011
    Location
    Charleston
    Posts
    3,309

    Default

    Quote Originally Posted by goosebegone View Post
    Confirm it’s a fuel delivery issue by running an external fuel tank straight to each motor. My guess bad bulb then check fuel line.
    This is the go to answer for any suspected fuel issue.

    Dump your separator and see if you have water/junk as a quick check.

    Were the bulbs compressed/collapsed or just lacked prime?

  8. #8
    Join Date
    Dec 2007
    Location
    Providence
    Posts
    6,189

    Default

    Quote Originally Posted by goosebegone View Post
    Confirm it’s a fuel delivery issue by running an external fuel tank straight to each motor. My guess bad bulb then check fuel line.
    This, isolate the issue.

  9. #9
    Join Date
    Jul 2003
    Location
    Moncks Corner
    Posts
    15,556

    Default

    Before I got to the end I started suspecting the fuel/water separators. You can actually take the ones you've got now and dump the contents (in an environmentally safe and environmentally conscious way) then reinstall and probably be fine for another year.
    Ephesians 2 : 8-9



    Charles Barkley: Nobody doesn't like meat.

  10. #10
    Join Date
    Dec 2002
    Location
    GREENWOOD
    Posts
    6,348

    Default

    This exact same thing happened to me on my Optimax 250 2 years ago when I put in ethanol free gas.

    I believe since e free gas is more expensive it sits in the tank longer and has more of a chance to get water in it from condensation and such.

    I would drain the tanks and fill with fresh gas , change any and all fuel filters, and change both bulbs.

    But before doing that hooking to an external tank would show you if what i said is the issue
    I am a nobody, that met somebody, that can save anybody.

  11. #11
    Join Date
    Feb 2004
    Location
    SC
    Posts
    4,304

    Default

    Sounds like water in the fuel. Easy check, run off remote above deck tank and then get to work siphoning out the onboard tanks. Here's a good tip for siphoning liquid with an air tank.

    Listen to your elders. Not because they are always right but because they have more experiences of being wrong.

    "We make a living by what we get, we make a life by what we give" Sir Winston Churchill

  12. #12
    Join Date
    Nov 2012
    Location
    Awendaw
    Posts
    2,031

    Default

    The collapsed bulb has me thinking you are getting air in the system. I second and third the portable gas tank and work back from there.

  13. #13
    Join Date
    Aug 2021
    Location
    NC
    Posts
    3,374

    Default

    I think an air leak as Fireman said. Also since both motors started acting up after fueling that is a good chance the problem.

  14. #14
    Join Date
    Nov 2013
    Posts
    4,992

    Default

    May need some verification...
    A collapsed/flat bulb is a venting problem. Empty, yet operable, bulb is either drawing air or a failing/failed fuel pump. Probability of both pumps failing that close together with the same symptoms is indicative of a supply or qulaity of supply problem to me.

    I feel like there is only one tank on those Gulfstreams....one racor, valved to both motors or are there saddle tanks/2x racors feeding each indvidual motor?

  15. #15
    Join Date
    Sep 2007
    Location
    Boone, NC
    Posts
    6,230

    Default

    Starboard bulb was collapsed at one point, but only temporary. Port never collapsed. Both were empty at one point as well, but also only temporary.

    There are two tanks on the boat. Honestly not sure on a racor, that’s above my level of knowledge.

  16. #16
    Join Date
    Nov 2002
    Location
    FloVegas SC
    Posts
    5,710

    Default

    Quote Originally Posted by Steel Slinger View Post
    I would replace fuel line as well. Bulb also. Fuel line could be colasped
    Quote Originally Posted by goosebegone View Post
    Confirm it’s a fuel delivery issue by running an external fuel tank straight to each motor. My guess bad bulb then check fuel line.
    Quote Originally Posted by huntinghagen#12 View Post
    Starboard bulb was collapsed at one point, but only temporary. Port never collapsed. Both were empty at one point as well, but also only temporary.

    There are two tanks on the boat. Honestly not sure on a racor, that’s above my level of knowledge.
    Do these things. Ethanol eats fuel lines from the inside out. I explain it like this, when you try drinking a milkshake with a straw, and the straw collapses. It's because the straw is too thin for the vacuum placed on it. If your bulb is collapsing, it is not because of air. Put a temp tank on it, and if it solves everything, then it's fuel lines. I would put the temp tank behind the fuel water sep first, then before etc. The HPDI is just that "high pressure" and they require good clean fuel to do their thing. Good luck, MG
    Last edited by Maggie Glover; 04-06-2023 at 10:34 AM.
    Dum Spiro Spero

  17. #17
    Join Date
    Sep 2007
    Location
    Boone, NC
    Posts
    6,230

    Default

    New fuel lines and bulbs are on the list of maintenance now.

  18. #18
    Join Date
    Jun 2011
    Location
    Columbia, SC
    Posts
    3,946

    Default

    Check your fuel pump too. I forgot to run the fuel out of the carbs and it sat for 8 months. My guy pulled the fuel pump apart and non ethanol fuel had crystallized in the pump. It was sucking air and the bulb wouldn’t stay tight.
    Sea Ark 1542 w/ Yamaha 40
    Xpress 16 w/ 50 Hammer
    War Eagle 15 w/ 30 Hammer

    --------------------------------------------------

    "Sometimes you gotta grab the bull by the horns and the women by the tits and take charge in your life" - General Patton

    "I'm very drunk and I intend on getting still drunker before this evening's over."
    - Rhett Butler

  19. #19
    Join Date
    Jan 2003
    Location
    SC
    Posts
    24,411

    Default

    Sounds like you overfilled the tanks and got fuel in the vent lines.

    Sent from my motorola edge plus 5G UW (2022) using Tapatalk

  20. #20
    Join Date
    Dec 2010
    Posts
    28,019

    Default

    both bulbs didn't go bad at the same time.
    They share the same tank, only common denominator?
    Unscrew one of your fuel water separators and dump it in a glass bowl and see what it looks like.
    If it's crappy, change them, drain VST tank and get good fuel and rock on.
    Go pull a spark plug before you run it again and see if they show any sign of rust.......proof of water in fuel

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •