1986 Yamaha 90HP 2 stroke missing/rough running

[spriessman\]

1986 90hp 2 stroke. Missing below 2,000RPM. Seems to be running on 2 out of 3 cylinders. 2,000 to 3,000RPM uneven power. RPMs surge, then dog down +/- 300RPM. Above 3,000RPM all seems good. Serviced 60 days ago for same problem while on vacation in Florida. Tech performed "100 hour" maintenance. Plugs. lower unit, impeller kit, $400. Tech writes "sea trail - found stalling a lot - adjusted carbs - ran at idle OK". Problem seemed solved - now it' back again - plus there is oil leaking on the transom mount and leaking from the lower cowl, down the left side of the leg. I pulled the plugs - look new from recent service, not fouled. Fuel is fresh marine gas. Any thoughts before I take back to the marina for another service??

 

[robert graham]

Re: 1986 Yamaha 90HP 2 stroke missing/rough running

"oil leaking on transom" sounds maybe like fuel/oil mixture leaking from carb due to bad carb float valve or carb level out of adjustment. Carb levels have to be set just right. Also, was factory specified link and sync procedure done after carbs cleaned. is fuel pump o.k.?

 

[spriessman\]

Re: 1986 Yamaha 90HP 2 stroke missing/rough running

Sorry - I don't have answers to your questions. Mechanical, I ain't. Now, if you asked me who signed the VISA charge to pay for the last maintenance - I could answer that question in a heartbeat.................me!! Using your observations, I'll coach the tech at the marina to check the carb float valves and levels, reminding him to do a factory spec-ed link and sync before he buttons things up. Thanksabunch for your help..................