I recently bought a '94 17.6' Champion with a Mercury 115HP. Have had it for about 2 weeks. Motor ran good,until a few days ago. A wake boat drove in front of me and sent a huge roller towards me. I was only running around 30 and as soon as I saw it I let off the throttle but the entire boat went airborne then struck the 2nd wave when it came down. After that, I could not get on plane. I believe that this motor idles and runs up to around 1800 RPM on 2 cylinders and then the other 2 kick in. It starts and idles like normal. When I try to accelerate and get on plane I can't get full throttle and you can hear it missing and feel it get really jerky. Before this, it would jump on plane almost instantly.
I pulled the cowling and didn't see anything abnormal on connections. I checked the plugs and one looked a little fouled so tonight I replaced all four. Took it to the lake, cranked right up, idled smoothly and as soon as I tried to get on plane, I started getting the same results. I thought that maybe the prop hit and somehow damaged the lower unit or bent the shaft but I get no vibrations and checking it out of water, it seems to be fine.
What would hitting a wave do that would make it start behaving this way? I'd like to check some obvious things before taking it to a mechanic but I'm at a loss at the moment. I first thought maybe it was debris in the fuel but the carbs have just been cleaned, filters replaced, all hoses replaced and fuel tank removed, drained and cleaned and the fuel is all fresh.