posted 10-03-2012 01:03 PM ET (US)
My 1991 90 horse Force outboard was used 4 hours this May after winter storage and then put out of commission waiting for some repairs to the drain tubes to be completed. I did not get the boat back in the water until August.Unfortunately I had not anticipated such a long time on the hard and I did not drain or treat the fuel in the engine.
When I ran the boat for the first time the engine was running very rough and only had about 2/3s of it normal power. I found that the middle cylinder was not firing. A new Spark plug fixed this.
However; the engine would start and idle but if you put it in gear gently it died. If you pop it in gear the engine ran fine, with a top speed around 39 MPH. My thought was the idle speed was set to low or the carburetors got gummed up from sitting for 3 months.
I ran Sea Foam threw 3 rounds of 6 gallon tanks and cleaned out the engine mounted fuel filter. The engine still would not go into gear without dying.
Yesterday I adjusted the idle speed up a little. Unfortunately I do not have a tachometer on the boat so I currently have no way to actually know the RPMs. But by my ear the engine sounded better. Tied to the dock I could put it in gear and the engine did not die.
I took her out for a test run, a WOT she ran great, the speed was right were it should be, then I heard a small clunk and the boat dropped to 10 mph. The engine sounds fine but that is all the power it has. It will still shift gears without dying but now is has no high-end.
Could this be electrical? It was such a sudden change I usually do not think of fuel issues being so sudden.