90s evinrude 88 v 4 missfire?

I recently bought a pontoon boat with a 88 v4 evinrude 1990s model. The boat sat for 2 years. I did a test run and the boat ran kind of ok. It had a sputter and was a bit sluggish at first. It started to run a little better after awhile. I drained and filled with fresh fuel mix, 50 to 1 premium and quicksilver also some seafoam fuel system cleaner. started and let run for about an hour. helped the idle and throttle responce but the sporatic miss stayed. I installed 4 new plugs and coils. the old plugs were wet on the right bank(fuel fouled) and the left had some carbon build up. the coils looked very bad, cracks, corrosion ect. Started er up and WTF? still a sporatic non rythematic skip or missfire. The idle is much better (when it doesnt skip) motor sounds very strong except for that g-dam ssskippp! What next?

Re: 90s evinrude 88 v 4 missfire?

You could have a misfire at idle, called a "lean sneeze." This is a carb problem. Also could be an ignition problem. Best to try to sort them out so you go in the right direction. It's probably easiest to start with the ignition side first. Warm the engine up , the use an inductive timing light to check the spark on each plugwire. The flashes in the gun will tell you if you have a miss, weak spark, or no spark. If the spark looks good/strong on all 4 plugwires, then turn to the fuel system.

Re: 90s evinrude 88 v 4 missfire?

Great advice above.

In addition, look at the temperatures of the two banks. If you have one bank running cold, it can cause running issues.

The banks should run about 140*, as measured at the head, and be with 10* of each other.