[outsick81]

I have a 1986 200hp Yamaha ETLJ. The motor only has approx 20 hours since a rebuild. It fires right up and seems to run fine at idle. All cylinders have spark and have nice even compression. If I bring the boat up on plane, it will run at 4200 rpm for approx 30 seconds before sputtering (as if it is starving for fuel). The motor does not die, it simply cpmes off plane spitting and sputtering. If I back off the throttle and idle, it is fine. I can also just barely plane out around 3200rpm and it will run fine. It is only at the higher rpm that I have issues. I felt the fuel ball and it is not hard (there is clearly air inside). The ball and line are only 6 months old and seem to look good. I cannot find any area that the engine is sucking air. The ball is also not sucked in as if there is a blockage, it simply feels too squishy as if it contains air. Could this be a fuel pump? Is there an easy way to check? Does anyone have any other ideas?

Thank you for your help!

[rodbolt]

did the carbs get rebuilt as well as the fuel pumps replaced?
if not look out for the 2nd rebuild.
also carefully check the connector on the engine lower pan, the oring can swell and block off the fuel flow. can be found by either bypassing it and plumbing direct to the filter or with a vacum guage Teed into the fuel line at the lower pump intake.

[Ray Neudecker]

I have also run into problems with the fiter housing itself causing a restiction on motors of this age. Install a water seperator filter and bypass the engine mounted one. Always clean and rebuild the carbs and replace the fuel pumps when rebuiding.

[outsick81]

Thanks for the ideas. The carbs were recently rebuilt. I am not sure about the fuel pumps being rebuilt. I will check for the O-ring on the lower pan.