'99 225 Ox66 Surging At Speed

[shadow1958]

I Have A '99 225 Ox66 That Has Started Surging As If A Fuel Or Electrical Problem. After Replacing And Servicing All Filters,/connections/hoses The Problem Remains. I Have Done The Portable Tank And Squeezing Of The Bulb With No Changes In Performance. Compression Is Good On All. Also Cleaned O2, And, While It Make A Difference On Smoothness At Idle, Did Nothing For Performance. What I Have Noticed Is The Engine Will Start, Idle And Run To Red-line Until It Basically Reaches Operating Temp And Then Starts To Drop Rpm's As If A Fuel Issue Surging Back And Forth As If Intermittent Fuel Starvation Or Spark Loss. However The Engine Never Stalls Out Completely. I Pull Throttle Back Rpm's Smooth Out Until I Try To Accelerate Then Surging Continues. It Does Appear I Have A Faulty Remote Tank Sensor And My Main Oil Tank Won't Refill Unless I Engage Manual Switch. Could This Sensor Be Sending False Info To Cdi Creating An Intermittent Shut Down ? Could There Be Any Other Electrical Part (rotor, Stator, Etc) That Could Fail As Temp Under Cowling Increases? Any Help Appreciated.

[jb123]

you need to TEST 02 sensor as it will cause rpm variations and not allow max rpms, and also if you havent recently, change stats.

[shadow1958]

reply

thanx............ what are stats

[Tucker]

Thermostats

[formula29]

I have the same problem with my 98 250, what would the thermostats have to do with it? is it was hot it would go into power reduction wouldn't it?

[Ray Alston]

Went thru the same exact scenario with my Carb. VMax 150. Argued with the tech about the problem he said was spark plugs. I said it couldn't be plugs, I had replaced them about 6 months ago. It was spark plugs. Runs like a champ now. Now I listen to the mechanic better than I did before......