User Tag List

Results 1 to 14 of 14
  1. #1
    Join Date
    Apr 2020
    Location
    Kentucky
    Posts
    7
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Merc Promax Issue og

    Jus bought a 1991 Bullet 21VEE thatís Got a 2000 Mercury 225 Promax on it. Boat was running fine and out of the blue it cut back to only about 4600 Rpm max. Wonít get on plane unless you run someone to the front of the boat. Once on plane max 4600 rpm then all of a sudden run perfect for a half mile or so then cut back to low power. When it is running right you can stop and get back on plane normal and run good then all of sudden back to low power. Run good then bog run good then bog. Only thing I did before the issue was change plugs. Went from BUHW to BR9HS gapped on 40. Figured Plugs should b changed for jus to know they were fresh. In neutral engine will rev up fine coughs a lil as it is decelerating but revs fine. Just under load the issue of not accelerating is happening. Any help is appreciated. I know Jay Smith and Chris Carson are a Promax guru well any outboard guru I should say hopefully them or someone like them sees this post. Thanks in advance

  2. #2
    Join Date
    Jul 2002
    Location
    FT WORTH, TEXAS
    Posts
    7,940
    Thanks (Given)
    9
    Thanks (Received)
    132
    Likes (Given)
    232
    Likes (Received)
    454
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    they are most likely too cold

  3. #3
    Join Date
    Jul 2002
    Location
    FT WORTH, TEXAS
    Posts
    7,940
    Thanks (Given)
    9
    Thanks (Received)
    132
    Likes (Given)
    232
    Likes (Received)
    454
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    try BR8HS

  4. #4
    Join Date
    Apr 2020
    Location
    Kentucky
    Posts
    7
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by TEXAS20225 View Post
    try BR8HS
    Had the BU8H in it not sure if they are hotter or colder but did it with them too. Wanted the BR8HS but local shop didn’t have em

  5. #5
    Join Date
    Apr 2020
    Location
    Kentucky
    Posts
    7
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by TEXAS20225 View Post
    try BR8HS
    Had the BU8H in it not sure if they are hotter or closer but did it with them too

  6. #6
    Join Date
    Jan 2002
    Location
    TX......somewhere?
    Posts
    5,629
    Thanks (Given)
    3
    Thanks (Received)
    193
    Likes (Given)
    89
    Likes (Received)
    575
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    its NOT plugs... tha bu8h's or buhw's should run jus as good as any.. what it does in neutral and/or ona hose will never be same as under a load.... sounds more like a switch box?.. maybe droppin' a cly. or two for whatever reason?...... but we're settin' here ona computer so..........................................................................
    Last edited by tlwjkw; 05-11-2020 at 12:57 AM.

  7. Thanks silverbullet02 thanked for this post
  8. #7
    Join Date
    Oct 2004
    Location
    FL / NY
    Posts
    8,671
    Thanks (Given)
    389
    Thanks (Received)
    386
    Likes (Given)
    5404
    Likes (Received)
    2235
    Mentioned
    1 Post(s)
    Tagged
    1 Thread(s)
    Check your plug wires for good tight connections or damage.

  9. Likes Dave Strong liked this post
  10. #8
    Join Date
    Feb 2009
    Location
    Edgewater,B.C. CANADA
    Posts
    8,083
    Thanks (Given)
    151
    Thanks (Received)
    279
    Likes (Given)
    3170
    Likes (Received)
    1114
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Think you answered your own question stating the issue started after plug change. Never know box could have been dropped during shipping making the plugs an issue. As Bobby said try a set of BR8HS and see what happens. Also as Tux stated the steel connector that clips on the top of the plug inside the boot can get loose. You should feel a positive snap as they clip on the top of the plug, if they are loose you can get strange things going on at different rpm.

    Dave
    1980 Cougar 19 tunnel,90 2.4L Bridgeport EFI in middle of restoration.
    1988 BAJA Sunsport 186, 96 225 Pro Max
    79 12' Auminum, 95 Merc 9.9
    RIP Stu
    "So many idiots, so few bullets"

  11. #9
    Join Date
    Apr 2001
    Location
    Western Pennsylvania
    Posts
    3,704
    Thanks (Given)
    46
    Thanks (Received)
    67
    Likes (Given)
    177
    Likes (Received)
    336
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Have seen some chat about amazon plugs are counterfeit china knock offs. If purchased there?
    http://www.stvowners.com

    Checkmate 2002 Convincor 270 496 MAG-HO

    2003 Cougar 22MTR w/300xs SOLD
    90 21Skater w/300xs - sold
    98 STV Euroski w/280 - sold


    2006 Trailblazer SS 6.0l 395hp

  12. #10
    Join Date
    Apr 2020
    Location
    Kentucky
    Posts
    7
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Did it with the old plugs too tried changing back

  13. #11
    Join Date
    Feb 2009
    Location
    Edgewater,B.C. CANADA
    Posts
    8,083
    Thanks (Given)
    151
    Thanks (Received)
    279
    Likes (Given)
    3170
    Likes (Received)
    1114
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Run it in the dark, mist the wires with a spray bottle of water if you have a spark leak it will show up.

    Dave
    1980 Cougar 19 tunnel,90 2.4L Bridgeport EFI in middle of restoration.
    1988 BAJA Sunsport 186, 96 225 Pro Max
    79 12' Auminum, 95 Merc 9.9
    RIP Stu
    "So many idiots, so few bullets"

  14. #12
    Join Date
    Apr 2020
    Location
    Kentucky
    Posts
    7
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Euroski View Post
    Have seen some chat about amazon plugs are counterfeit china knock offs. If purchased there?
    Bought the plugs from Advance Auto Parts they had them in stock

  15. #13
    Join Date
    Jul 2002
    Location
    FT WORTH, TEXAS
    Posts
    7,940
    Thanks (Given)
    9
    Thanks (Received)
    132
    Likes (Given)
    232
    Likes (Received)
    454
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    weird it started when you changed plugs

  16. #14
    Join Date
    Apr 2020
    Location
    Kentucky
    Posts
    7
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Still chasing the issue waiting on a DVA adaptor to come in the check the issue further

Similar Threads

  1. Mercury Tech: 225 ProMax issue
    By sv10001975 in forum Technical Discussion
    Replies: 9
    Last Post: 05-18-2019, 07:46 PM
  2. Full throttle issue. 225 promax.
    By madtunnel in forum Technical Discussion
    Replies: 2
    Last Post: 10-03-2018, 09:38 AM
  3. Mercury Tech: 2.5 225 Promax Fuse issue
    By Hydro-Peep in forum Technical Discussion
    Replies: 11
    Last Post: 05-04-2017, 09:31 AM
  4. Promax 225 cutoff issue!
    By drjerry1st in forum Technical Discussion
    Replies: 3
    Last Post: 03-14-2012, 04:40 PM
  5. 300 promax starting issue?
    By billyindex in forum Technical Discussion
    Replies: 7
    Last Post: 07-14-2007, 08:44 PM

Tags for this Thread

Posting Permissions

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