Results 1 to 6 of 6

Thread: Lean?

  1. #1
    Schiada76
    I was running my 21 this weekend with a basically stock Mark IV, 750 Holly double pumper, mechanical advance carb when it went lean at about 3/4 throttle. At least all the plugs are showing lean.
    It was Sunday at Parker it looked like Victory At Sea and I was banging it pretty hard when it felt like I dropped a couple of cylinders. Could this cause a float to hang up? Oil temp and water temp were perfect and the plugs look perfect except for looking lean. I didn't have time to try and trouble shoot it before we left.
    It still fires right up, idles and made it back to the ramp ok.

  2. #2
    Senior Member
    Join Date
    Feb 2009
    Posts
    678
    I was running my 21 this weekend with a basically stock Mark IV, 750 Holly double pumper, mechanical advance carb when it went lean at about 3/4 throttle. At least all the plugs are showing lean.
    It was Sunday at Parker it looked like Victory At Sea and I was banging it pretty hard when it felt like I dropped a couple of cylinders. Could this cause a float to hang up? Oil temp and water temp were perfect and the plugs look perfect except for looking lean. I didn't have time to try and trouble shoot it before we left.
    It still fires right up, idles and made it back to the ramp ok.
    i'm no expert, but it sounds to me like u ran the carb out of gas due to the choppy water causeing the floats to bounce up & down...try it again under better conditions!...just my .02 cents
    fastrat

  3. #3
    jbone
    Like Fastrat said, or the jets could have sucked air if the float levels are a little low. I've never used the extended jets, but they might help in those contitions.
    Just a thought,
    J

  4. #4
    fc-pilot
    You can try the spring loaded needle and seats. Have run them in a few flats with good results. It just eliminates one more thing to give you fits.
    Paul

  5. #5
    Schiada76
    It wasn't temporary.
    Cruised slowly back to our buoy, pulled all plugs and they were VERY clean even after the low speed return to home and idling up to our buoy.
    When I left for the ramp I got a couple of lean pops if I put my foot in it at all.
    I didn't check the filter (Mallory canister) but it would take a ton of crud to clog it that quick plus it was a brand new filter. Boat ran fine all week long it was that "just one more run" with the kids that got me.

  6. #6
    Senior Member
    Join Date
    Jun 2009
    Posts
    10,871
    Check...
    Fuel pump
    Fuel filter
    for split in fuel line sucking air
    fuel line collapesed on the inside not allowing flow
    put a temp fuel pres gauge on it and take it out and isolate the problem. shouldn't be too hard to find if its that lean.

Similar Threads

  1. Lean condition with the Sanger
    By Dominator Scott in forum Jet Boats
    Replies: 6
    Last Post: 05-10-2007, 02:41 PM
  2. lean problem!
    By bakerjet in forum Jet Boats
    Replies: 3
    Last Post: 06-04-2006, 08:18 PM
  3. Fat / Lean Question
    By vdrivenman in forum V-Drives
    Replies: 13
    Last Post: 05-28-2006, 08:16 AM
  4. I'd say she was little lean
    By Fiat48 in forum Gear Heads
    Replies: 13
    Last Post: 03-03-2006, 04:33 PM
  5. Lean to rich
    By Thunderbutt in forum Gear Heads
    Replies: 5
    Last Post: 07-22-2003, 08:42 AM

Posting Permissions

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