1978 johnson 85 hp question

Hey guys, I have a question for a friend. He just bought a 85 hp Johnson, and it runs great. It starts up immediately, pushes his boat great, and after you shut it off, will dang near immediately start up again. Heres the problem however. After he makes his main run up the lake, he shuts off the motor and fishes for a few hours. He will restart the motor, and head to another spot. The motor will hesistate a little bit at WOT. He can let down on the throttle, reopen it, and it will immediately plane out again, only to hesitate a bit more after a few seconds. My first thought was bad gas (had 4 gallons of 10 month old gas in there, mixed with about 12 gallons of fresh), but wouldnt that cause the engine to hesitate all the time? My next thought is a coil or powerpack. Compression is good, and the motor will always start as soon as he turns the key. Motor idles great at all times.

Any ideas?

Thanks guys!!


Modified by JoshKeller at 11:48 PM 2/26/2006

Sounds like the high speed jets are clogged. How long has it been since the carbs were rebuilt?

About a month ago. I just dont understand why it runs great at wot the first 2 miles up the lake?

What oil to gas ratio do you use? I have a 1985 115 and when I ran 25:1 it would miss at high rpms. I backed off a bit to about 40:1 and it stopped. Hope this helps

I am running 48:1

Have you tried changing the spark plugs? Power pack?

Put new plugs in her gapped to .030 when he bought the motor. I'm going fishing with him tomorrow, and when it starts to miss again, i'll switch out the power packs and coils on 1 side to see if we can isolate the problem.