Logo
Get instant online access to repair manuals for your Mercury / Mariner outboard. Online Manuals
MercuryMariner
Order printed Mercury / Mariner service manuals — shipped to your door! Printed Manuals
MercuryMariner
Use engine diagrams to find & order parts for your Mercury / Mariner engine. Engine Diagrams
MercuryMariner
Find parts quickly with Mercury application guides. Quick Parts Guide
MercurySierraCDI
Results 1 to 13 of 13
  1. #1

    Question 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    Ok so maybe she's right. But at this point I really want to fix this thing myself. Local shops are backed up 2 weeks+ anyway. I might as well keep trying. I'm just going to put as much info down as I can think of.

    Here's what I've got:
    2012 8hp
    Mod: 1F08201FK
    Ser: 0r517065
    pull-start/tiller

    Here's what it's doing:
    A couple months ago I was cruising along WOT (generally about 20mph) when it quickly bogged then came back bog a little longer then came back. I thought it must've been an air bubble or a little condensation or something. Didn't think much else of it.
    Next trip or two it was fine. Let me add that this is mounted on a Gheenoe fishing machine - I don't have to run more than 5-10 minutes to get to my spots.
    Pretty soon it started happening again. I was a little more concerned but didn't have a ton of time to dig in and it wasn't stopping me from fishing.
    At this point it only runs properly intermittently - not the other way around. It runs rough with or without load and WOT is giving me around 40% power.

    Here's what I've done to it:
    started by changing out the gas - just did this again non-ethanol
    rebuilt the carb - then rebuilt it again with the kit for new seals and gaskets
    rebuilt the fuel pump with new diaphragm and gasket
    engine oil and gear oil are changed regularly and look good
    plugs look good - light blueish spark

    Other info:
    engine looks great - timing belt looks brand new - telltale is strong and warm
    each time I fix something at home - it seems to run well until I put it in the water
    back in 2017 it was totally underwater for less than a minute - I followed some online guides and it's been running great until recently

  2. #2
    Join Date
    May 2013
    Location
    TX.
    Posts
    530

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    You didn't mention engine on board fuel filter. You can remove it and see if you can carefully exhale through it. If not clogged, if so, might as well change it out anyway since you have it off. Change it and cut the old one open. If full of black, engine fuel lines degraded. If full of yellow chip type stuff, time for a new engine to tank fuel line with squeeze bulb.

  3. #3

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    Quote Originally Posted by Texasmark View Post
    You didn't mention engine on board fuel filter. You can remove it and see if you can carefully exhale through it. If not clogged, if so, might as well change it out anyway since you have it off. Change it and cut the old one open. If full of black, engine fuel lines degraded. If full of yellow chip type stuff, time for a new engine to tank fuel line with squeeze bulb.
    I knew I was forgetting to mention something. Yes I changed the fuel filter and it was clear.

  4. #4
    Join Date
    Sep 2010
    Posts
    20,968

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    Compression checked ?---Post the numbers.-----Does spark jump a gap of 3/8" on both leads ?----Valve clearance checked ?

  5. #5
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    16,990

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    Listen to your wife! (Besides, it will keep you out of trouble.)

    Jeff

  6. #6

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    I get it. Like I said shops around me are backed up right now.
    Also, I'm in this to learn. I've learned a lot by working on my truck.
    I want to exhaust my options first.

  7. #7

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    Quote Originally Posted by racerone View Post
    Compression checked ?---Post the numbers.-----Does spark jump a gap of 3/8" on both leads ?----Valve clearance checked ?
    Compression 110 and 112
    Yes spark jumps the over-gapped plug - I remembered your post wrong and set the plugs to .038 (factory is .033). It's hard to me to check a 3/8" jump as it's a pull start, but I doubt it would.

    side note: ran rough warming up for compression test but ran great for a couple minutes after (had to shut it off to leave). Warm/cold hasn't seemed to matter in the past. But again it seems like every time I tear something apart it comes back strong for a time.

    Haven't checked valve clearance.

  8. #8
    Join Date
    May 2013
    Location
    TX.
    Posts
    530

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    ⅜" is 0.375". Everybody has their pet number for an ignition testing gap in free space (as compared to the actual plug gap for firing under pressure in the cylinder). I see " more often (0.250). Merc. has a spark tester that you see mentioned off and on in forums. I forget it's gap.

    Plug gaps vary per engine and plug type. Numbers like 0.030" and 0.035 were popular numbers with old ignition coil/points systems whereas new Merc 40kv electronic capacitor discharge run 0.040" plug gap.....at least on my 90 and 115 2 strokers. Your compression numbers aren't all that bad but the serv. manual for these engines mention that anything below 120 you could expect problems. Course compression measuring is extremely subjective depending on equipment, procedure, and integrity of each measurement...example some plugs are under a cowl and hard to get in and get a good reading as compared to the plugs directly accessible.
    Last edited by Texasmark; 12-02-2020 at 10:28 AM.

  9. #9

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    Thanks for the reply. I’m holding the plug closer to 1/4” but also ripping the cord so who knows how close I really am haha. The .033 was listed on the table on this site for the 209cc USA version.

  10. #10
    Join Date
    May 2015
    Posts
    2,430

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    Did you have the throttle open for the test? The 120 # that was given you was for 2 strks. Get a spark tester that clamps on to a bolt.

  11. #11

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    Quote Originally Posted by flyingscott View Post
    Did you have the throttle open for the test? The 120 # that was given you was for 2 strks. Get a spark tester that clamps on to a bolt.
    I did have the throttle open (although the first time I forgot to open the throttle and did I it cold and my results were around (105 each cyl). I know most 4 strokes are typically much higher 180-200+

  12. #12
    Join Date
    May 2013
    Location
    TX.
    Posts
    530

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    "The 120 # that was given you was for 2 strks."

    Yepper. Keep forgetting to pay close attention to stroke type and EFI or not. Caught up in my little world obviously.

  13. #13

    Default Re: 2012 8hp Wife said "Why don't you take it to someone who knows what they're doing"

    Just to follow up. I don't know why the compression is what it is...
    I pulled the carb again and double checked jets (found an issue), new plugs and throttle adjustment, and we're back on target.
    From the start it was probably a combo of bad gas with some minor obstruction in the line, tired plugs, worn diaphragm in fuel pump and low compression causing the issues. Now she cruises at wot, idles strong and everything in between
    Now to re-prop.
    Thanks for all your help!

Similar Threads

  1. Replies: 6
    Last Post: 07-04-2017, 08:30 AM
  2. 2012 DT40 "he made me do it" HELP!!!
    By Whoops my bad in forum Suzuki Outboard Forum
    Replies: 1
    Last Post: 07-23-2013, 09:00 AM
  3. Design Feature "V" - "Special Gearcase" - What does this mean? J150VXSIG
    By weirdaljr in forum Johnson Evinrude Outboard Forum
    Replies: 4
    Last Post: 05-14-2011, 09:59 AM
  4. Replies: 3
    Last Post: 02-22-2011, 12:31 PM
  5. Replies: 4
    Last Post: 01-19-2011, 04:28 PM

Posting Permissions

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