I bought a couple weeks ago, and my family went to the coast for a week on vacation. It worked great for 30 minutes and then it wasn't going full throttle and now it won't even turn over. I put new plugs in it yesterday and it started for 10 seconds or so then I turned it off. Then I put the water adapter on to clean out the saltwater, but it cut out after about 20 seconds. Now it won't start again. Both the plugs were good before I put them in, but when I went to take them out they were all black and oily. Want would make the plugs foul so quickly? Thanks for the help