[88maverick]

Thanks for any suggestions. For the past year, my 1998 Yamaha 130 (1,000 hrs on hr. meter) has been fouling the plugs on the port side after 15-20 hrs. of use. The boat is used on sea turtle surveys here in the Keys and is driven 60 miles on each trip. The plugs get gas-fouled, especially the bottom port side cylinder. While checking for turtle nests, we idle along the beach and stop as we find nests. When we get to deeper water and try to plane the boat, it has no power, but runs great again after we change out the fuel-fouled plugs. It's driving us crazy. ANY SUGGESTIONS WOULD BE GREATLY APPRECIATED. THANKS. Tom, Big Pine Key, FL

[spete]

Some suggestions that might help or at the very least get your topic bumped up to the top of the board. Have you ever had the carbs rebuilt? If not, it's probably time ... relatively easy job if you get a manual. A little strange that only the port side is fowling plugs - you may want to run some WD-40 through the crankcase vent hoses/make sure the check valves aren't gummed up. Put some WD-40 in the hoses and blow it through/un-gum the hoses. Check the ground wires on each of the coils and make sure that they don't have any corrosion and that they are securely fastened. You may want to de-carb the cylinders by running some Yamaha Ring Free in your tank in the shock dosage. Also, I'd replace the thermastats if they haven't been done in a while - perhaps the port bank is sticking open and causing those cylinders to run cold and foul at idle. Just some thoughts. Good Luck!

[88maverick]

Spete:Thanks for the excellent advice. Thermostats are original and carbs never rebuilt or cleaned. Will give those suggestions and each of your others try. Yes,it is strange that only the port side cylinders are fouling plugs every 15 hrs. or so. My best from Big Pine Key, Tom.

[spete]

May also want to try a new set of plugs gapped to factory specs (my book indicates NGK BR9HS-10 for the 130hp - maybe you have two plugs in a different model/heat range than the other two - make sure all plugs are marked the same. Gap should be .035 - .039" or .9 - 1.0 mm) Could try some new plug wires (although I'm thinking that they should still be good on a '98 motor)Remove the black plastic cover that cases your CDI unit and check that all grounds are also secure. I checked mine - a 1998 - 115 hp and there was a loose connection inside. CDI unit may also be malfunctioning but doubtful. One last thing to check is the pilot screws - port side of carbs should match up to the other side. All four screws (these are the spring loaded screws that go into the front quarter section of your carbs) should be backed out from a gentle seat aprox. 1 - 1 1/8 turn.

[spete]

One last thing - if boat is on the water and you're using island gas there may be potential for a bad fuel situation/water in fuel - Might want to look at installing a Racor fuel filter/water separator.

[88maverick]

Spete:Great advice again. Changed thermostats on both sides. They were both nasty looking despite fresh water flushing and am glad I replaced them both. I am still working on the other excellent suggestions you made. I'll let you know what I find. Thanks again. Tom Wilmers, Big Pine Key.

[foker500]

I'm curious, did you ever figure out the problem. I'm have the same troubles with my engine. It's a 95 Yamaha 200 Pro V.