2000 DT225 High speed problem

[baldbob]

Hi all,
Happy Memorial day !I think I had some bad gas because the engine would run good then not idle well or go above 1800 rpm. It would then kick in again for awhile. Gas was over a year old stored with stabile ethanol enzyme treatment and seafoam. 90 gallon tank with 40 gallons in it. I added another 40 gallons of fresh gas and after a 10 minutes it was working fine. Now it wont go over 1800 in forward but hits high rpm 3500 in reverse. I'm really scratching my head on this. If its the gas I'm not sure why it has no problems in reverse. I've added a new fuel/water separator and more fuel treatment and still no high rpms in forward. Compression is perfect. Any suggestions?
Thank in advance

[Solarman]

Sounds odd. Does the throttle linkage on the throttle body move identically in both forward & reverse?
Maybe a shift switch is bad in one direction but not the other?

Good luck, post back if you find anything?

[seaox230c]

Different loading on the engine will produce different rpm's...in N you can hit several thousand rpm's with only 1 or 2 plugs connected. If you want to know if its fuel related...get a 6 gallon aux tank and run off that...if you hit your desired rpm's then you have bad gas in tank...if not you have other issues and we need to start digging...First question..carbs or fuel injection

[baldbob]

dt225

Throttle linkage good. Gooding to hook up a 6 gallon tank and see how it goes. I guess if its bad gas I'll just have to run the last 50 gallons at 1800. Could be a very long boat ride. Don't know any other way to get that much gas out. I hoping that doesn't do even more damage. Thanks for the suggestions

[baldbob]

Throttle position sensor

Turned out to be a bad TPS