1994 Yamaha 200 saltwater series rough idle

whitepursuit2150 · #1 October 3rd, 2007, 04:14 PM

I have a 1994 pursuit 2150 with a 1994 200hp yamaha saltwater series motor. The motor has been running great since i rebuilt the carbs and changed the plugs 4 months ago. I use the boat 1-2x weekly. recently (this week) the motor started running rough at idle, with the powerhead shaking a lot. I have also noticed a film of oil/gas on the water when I am sitting still with the motor running. I dont really have any problems starting the motor. After I motor up to around 2500rpm-->wide open, the symptoms disappear. I am currently undecided between a cracked plug, bad plug wire, timing being off, or low rpm coil pak going bad. Any feedback?

Thanks!

njohnson1960 · #2 October 3rd, 2007, 05:17 PM

You have ethanol in your gas? I will not fill up any more without adding STARTRON. My 115 Yamaha was running really rough at idle I had to rebuild Fuel Pump and Carbs last year because of the algae growth issue. I added STARTRON and the engine has never run better since it was new in 2003.

whitepursuit2150 · #3 October 3rd, 2007, 09:23 PM

No, no ethanol. I am in Florida, and the stations that use E85 have it pretty well marked.

Ray Neudecker · #4 October 3rd, 2007, 11:42 PM

Did you replace the fuel pumps?

whitepursuit2150 · #5 October 9th, 2007, 02:55 PM

No, I didn't think about replacing the fuel pump. Do you think that may be the problem, even though the high RPM's aren't affected?

Ray Neudecker · #6 October 9th, 2007, 07:31 PM

The symptoms of rough idle and oil and fuel in the water indicate a stuck needle or leaking fuel pump. Basically, I have found that if fire is there at any check point that an electrical problem is very unlikely on those models.