Please note this thread has been inactive for 90 days. For the best results, please start a new thread.
Results 1 to 20 of 20
  1. #1
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default 470 MCM Mercruiser fuel pump?

    Took the boat out on Saturday and it would stall during both acceleration and deceleration it would also idle rough and die when trolling. Then it would work fine for 10 minutes. When I got home I checked the fuel filter and it was dry. I'm thinking I need a new fuel pump?
    My next question is how difficult is it to replace the manual fuel pump with an electric?
    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

  2. #2
    Moderator Bondo's Avatar
    Join Date
    Apr 2002
    Location
    The Mouth of the Chaumont River, Ny.
    Posts
    52,761

    Default Re: 470 MCM Mercruiser fuel pump?

    Ayuh,... I'd sooner think you have a restriction, Upstream from there....
    Any Grease is Better,..... Than No Grease at All.......

  3. #3
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default Re: 470 MCM Mercruiser fuel pump?

    You thinking in the fuel tank? I'll check that, but shouldn't there have been fuel in the filter? It shouldn't be draining back past the pump? The return line is on the other side of the carb.
    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

  4. #4
    Ensign EddiePetty's Avatar
    Join Date
    Aug 2008
    Location
    Courtland, Virginia
    Posts
    998

    Smile Re: 470 MCM Mercruiser fuel pump?

    Quote Originally Posted by IceWater View Post
    You thinking in the fuel tank? I'll check that, but shouldn't there have been fuel in the filter? It shouldn't be draining back past the pump? The return line is on the other side of the carb.
    Okay, ICEWATER......I'll bite. What kinda carb'ed 3.7 has "The return line on the other side"?

    If you would disconnect the flexible fuel line on the suction side of the mechanical and splice in a temporary fuel supply, you could isolate your problem to correct side of the pump.

    I gotta agree with the 'ol BondO.
    Eddie Petty. #3 Dirt Modified
    Courtland, Virginia
    V-20 Wellcraft
    3.7 470 Mercruiser

    Stumpnocker
    25 Yamaha, 25 Johnson, 25 Evinrude, 9.9 Evinrude, 4 Johnson, 2.5 Johnson

  5. #5
    Cadet
    Join Date
    Jul 2010
    Location
    Indianapolis
    Posts
    4

    Default Re: 470 MCM Mercruiser fuel pump?

    On top of that... the mechanical fuel pump is not hard to change and not that expensive.. I got a new sierra marine replacement on ebay for about $70.00. For my 470. I would just stick with the mechanical.

  6. #6
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default Re: 470 MCM Mercruiser fuel pump?

    When I look at me carn there is a metal line from the fuel pump to the carb which unbolts to reveal the fuel filter. Directly across from the fuel filter there is a flexible rubber hose that goes back to the fuel filter. Is that rubber hose not a return line? Perhaps I'm confusing the fuel return system on my C15 CAT with a gasoline system?
    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

  7. #7
    Commander zbnutcase's Avatar
    Join Date
    Sep 2009
    Location
    Back seat of short bus
    Posts
    2,055

    Default Re: 470 MCM Mercruiser fuel pump?

    No not a return line, its there in case of pump diaphram failure to direct fuel to dump into carb, not the bilge
    You meet the nicest people at the American Legion.
    "maintenance is always cheaper than neglect"
    "certain parts are USCG approved for a REASON"
    "just because it's in the factory service manual, doesn't mean it's correct"

  8. #8
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default Re: 470 MCM Mercruiser fuel pump?

    Ok, that makes sense. I thought it was a return line because I have only seen a second line used as a return line.

    I'll run the fuel pump tests next time home Ande take it from there. If I do go with a new fuel pump I'll probably just stick with a manual' but I will add a water separater.
    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

  9. #9
    Ensign EddiePetty's Avatar
    Join Date
    Aug 2008
    Location
    Courtland, Virginia
    Posts
    998

    Smile Re: 470 MCM Mercruiser fuel pump?

    Quote Originally Posted by IceWater View Post
    When I look at me carn there is a metal line from the fuel pump to the carb which unbolts to reveal the fuel filter.
    IceWater.....you ARE aware that there is another fuel filter inside that little metal can on top of your fuel pump...aren't ya'?
    Eddie Petty. #3 Dirt Modified
    Courtland, Virginia
    V-20 Wellcraft
    3.7 470 Mercruiser

    Stumpnocker
    25 Yamaha, 25 Johnson, 25 Evinrude, 9.9 Evinrude, 4 Johnson, 2.5 Johnson

  10. #10
    Fleet Admiral
    Join Date
    Aug 2004
    Location
    East coast NJ
    Posts
    8,215

    Default Re: 470 MCM Mercruiser fuel pump?

    depends on the exact fuel pump used .Some AC type didnt have it.
    http://www.*****************/parts/si...ercruiser.html
    this type does
    Attached Images Attached Images

  11. #11
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default Re: 470 MCM Mercruiser fuel pump?

    Eddie Petty,

    I didn't check the filter on the pump, regardless, my original question was whether or not there should be fuel in the filter in the carb? I don't know much about boats at all, that's why I ask. I know a lot about trucks and a lot about 1960's Fords , but boats are very different.
    No one has answered whether or not there should have durl in the carb filter? I think there should; a boat isn't that different than a 1967 Cougar.
    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

  12. #12
    Fleet Admiral
    Join Date
    Aug 2004
    Location
    East coast NJ
    Posts
    8,215

    Default Re: 470 MCM Mercruiser fuel pump?

    There was a TSB saying to remove the carb filter because of restriction.With a filter on the pump and/or a fuel/water sep filter ,it`s all you need.

  13. #13
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default Re: 470 MCM Mercruiser fuel pump?

    Please excuse the spelling, I'm using my BlackBerry and it has a mind of it's own. Durl should be fuel and carn should be carb.
    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

  14. #14
    Senior Chief Petty Officer
    Join Date
    Apr 2009
    Location
    Richmond/Montross, Va
    Posts
    794

    Default Re: 470 MCM Mercruiser fuel pump?

    Quote Originally Posted by IceWater View Post
    Eddie Petty,

    I didn't check the filter on the pump, regardless, my original question was whether or not there should be fuel in the filter in the carb?.
    Yes, there should be fuel in the filter. And in the carb. The answers were that there are other things to check before assuming that the pump is the problem.
    '86 Glastron Conroy X-19
    Merc 170

  15. #15
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default Re: 470 MCM Mercruiser fuel pump?

    But, isn't the lack of fuel in the carb filter a sign that the fuel is leaking back past the fuel pump? Where else can it go? No signs of leaking.
    The most common answer on replacing the manual pump with an electric - provided the fuel pump needs replacing - is to just replace it with a manual' so that's what I'll do.
    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

  16. #16
    Senior Chief Petty Officer
    Join Date
    Apr 2009
    Location
    Richmond/Montross, Va
    Posts
    794

    Default Re: 470 MCM Mercruiser fuel pump?

    Quote Originally Posted by IceWater View Post
    But, isn't the lack of fuel in the carb filter a sign that the fuel is leaking back past the fuel pump? Where else can it go? No signs of leaking.
    Not sure what you mean. No fuel at the carb only means you aren't getting fuel to the carb. For any reason, including a fuel pump. Or empty gas tank. Or clogged upstream filter. Or...whatever.

    Quote Originally Posted by IceWater View Post
    The most common answer on replacing the manual pump with an electric - provided the fuel pump needs replacing - is to just replace it with a manual' so that's what I'll do.
    Ok. Then, if that doesn't work, you can troubleshoot your problem...
    '86 Glastron Conroy X-19
    Merc 170

  17. #17
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default Re: 470 MCM Mercruiser fuel pump?

    Not doing anything until I jbow what the problem is, that's why ask.
    I didn't have time to go through the manual and do the fuel pump test, but I was hoping to get a few clues from the few things I did do before I had to hit the road.
    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

  18. #18
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default Re: 470 MCM Mercruiser fuel pump?

    Finally got a few minutes today to run a test on the fuel pump and guess what? I need a new fuel pump.

    First thing I did was to remove and inspect the fuel filter in the fuel pump...not good...





    After that I removed the fuel line from the tank to the pump; it's worse, yet wasn't leaking..yet.







    I'm sure this was the original fuel line.

    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

  19. #19
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default Re: 470 MCM Mercruiser fuel pump?

    Next I tackled the fuel pump diagnostic test outlined in this:



    The first test I did, with the new fuel line, was using a jerry can for a gasoline supply and a second jerry can to measure the out put...there was next to none, a slow, inconsistent, small stream of fuel after about 7 seconds of the engine turning over. She's toast. Clearly the engine was using it's own vacuum to pull fuel through the line. I should have had to row home. Dumb luck that I didn't.



    To be sure the pump was beyond hope, I ran another test, this time with the boat fuel tank for supply and also with the fuel pump filter removed. Same result.




    I am ordering the parts from I-Boats, the least I can do after they provided this incredible forum which has saved me thousands in repairs. They are also much cheaper than purchasing a fuel pump here in town. The local Mercruiser dealer wants $450 plus taxes which are another 10% on top! Welcome to Canada, eh? I-Boats want $116 plus shipping and exchange, so maybe $150 Canadian delivered to my door. Pretty simple math.
    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

  20. #20
    Seaman IceWater's Avatar
    Join Date
    May 2010
    Location
    Saskatoon Saskatchewan Canada
    Posts
    55

    Default Re: 470 MCM Mercruiser fuel pump?

    Took about a week, but the new fuel pump arrived - thank you iboats! - and then it took another week before I got home to put it on. There were a couple of small snags, the biggest being that the fuel intake fitting from the old pump would not fit into the new pump, just wasn't going to happen, So I took part of the old pump and put it onto the new pump: Success!

    New Pump.


    Out put fitting. Clearly it has been blocked off for a very long time, but not the most significant problem.


    This was the big problem with the fuel pump. it is obvious that fuel has been leaking past the diaphragm for sometime. There is far too much corrosion in that spring for it to be a recent leak.


    Installed.


    Well, that is one problem fixed, now to replace the oil lines from the trim pump to the gimbal housing; leaking like a sieve. Oh, joy!
    I heard that the happiest 2 days of owning a boat are the day you buy it and the day you sell it, glad to say that doesn't apply to me!

    My 1980 Silverline Nantucket 17VBR

Similar Threads

  1. Mercruiser 350 magnum ski...fuel pump? Fuel lines clogged?
    By dutchbroracing in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 0
    Last Post: May 30th, 2010, 01:43 PM
  2. Mercruiser Fuel Pump
    By frostywalrus81 in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 16
    Last Post: May 19th, 2009, 12:04 PM
  3. Where is the fuel pump on a MerCruiser 350?
    By kylieholt in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 7
    Last Post: January 21st, 2009, 07:42 PM
  4. 5.o mercruiser fuel pump
    By jbenckert in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 2
    Last Post: April 15th, 2007, 04:55 PM
  5. Replies: 2
    Last Post: April 12th, 2002, 03:38 AM
  1. iboats Forum Directory - Over 100,000 forum posts organized by topic