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  1. #1

    PTO Spark Plug keeps fouling on new rebuild

    Hey Everyone,

    I have a 96 GTI dual carb. I just installed and broke in a new SBT motor. While I had the motor out, I cleaned the carbs and re-set the low speed screws to factory (1 1/4 turn out i think?). I replaced the spark plugs after the break-in process.

    I am on my second tank of gas after break in, and I noticed that after a 3 minute no wake zone, it wants to cut out if I gun it (normally from idle its fine when not idling in no wake for a long time). I look it up, and it looks like it's loading up, so I turn the low speed screws 1/4 turn in. It seems to be bogging less with the fix, but after about an hour of running I start losing top rpm. As I'm running it back to the marina, it's getting slower, and slower, and slower.

    I think that maybe it's a charging issue, but I threw my multimeter on it, and it's charging normally/the battery is fine. Then I decide to pull the plugs and this is what I'm looking at:


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    The PTO plug is totally fouled, but the mag plug looks fine. Do you think this is a carb issue, or maybe I need to snip 1/4" off the plug cable? Full disclosure, I left the gap on the new plugs on factory settings, it was probably .25 or so.

    What could this be? Do I need to turn the low speed screw on the PTO carb in a little more?


  2. #2

    Join Date
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    how was your pop off pressure?

  3. #3
    Pop off is fine, 27-30psi. When I replace the plugs, we're back in business, and it runs fantastic (minus the loading up in the extended no-wake zones). I would just prefer not to have to change the plugs after every tank of fuel.

  4. #4
    1983's Avatar
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    Did you change needles and seats in carbs? If not change them and it should solve your problem.

    Rob

  5. #5
    I found the issue.

    The choke butterfly valve on the PTO carb wasn't staying in place. The nut was on there tight, but it had about 3/4" play in it left to right, so it wouldn't stay open. As a result, I was running around with a partially closed choke valve on the PTO carb.

    I threw a couple washers behind the nut with some loctite, and now its opening and closing like it's supposed to.

  6. #6
    Quote Originally Posted by sookati View Post
    I found the issue.

    The choke butterfly valve on the PTO carb wasn't staying in place. The nut was on there tight, but it had about 3/4" play in it left to right, so it wouldn't stay open. As a result, I was running around with a partially closed choke valve on the PTO carb.

    I threw a couple washers behind the nut with some loctite, and now its opening and closing like it's supposed to.
    Well, I'll be damned.

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