SOS! '90 Merc 100Hp 2+2 troubles!

boatinnjax

Cadet
Joined
Feb 26, 2008
Messages
21
Had the boat out last weekend. she was running fine (I thought), when the
4th cylinder apparently kicked in, wow, then she really ran well! I had to thottle back ' cuz I was approaching a bridge. We then fished a spell and started back. On return trip the motor did not run well and died when I throttled down to Idle speed. No restart, uh oh! I changed top 2 plugs, still no restart. Paddled to shore. Next day, it fired up immediately in the drive way!
Took her out yesterday (with Multi meter and timing light in hand). Started immediately in the drive way - let's go! Backed her down the ramp, splashed her and parked the truck. Back at the ramp, Guess what? She won't start! Talk about embarrassing! Pulled out of the way with my trolling motor and went to work. I had fuel and spark to all 4 cyl's. Plug #1 and #3 were wet (gas), # 4 was wet (gas) and very oily. Spun motor over to clear it (after grounding plugs). Cleaned or replaced plugs. She would not start. When I hit the key motor cough's like one cylinder fires and then just spins, pulled plugs -wet (gas) again. Checked timing - on the mark at 25 degrees. Cleared and cleaned plugs 4 times, same thing.
What's going on here? Weak spark?
 

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: SOS! '90 Merc 100Hp 2+2 troubles!

With that system weak spark is about imposable, you either have it or don't can't really come to much of a answer from your description but it sounds like it could be flooding out.
 
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