Yamaha outboard-RPM's fall at WOT

[kevinburns]

I have a Saltwaer Series 250HO outboard motor. No one seem to be able to cure my problem...At WOT or any point above 4,000RPM's the motor starts to act like it is fuel startved and the RPM's start to drop...all the way to about 3800. At WOT I am normally pulling about 5400 to 5600 RPM's . A quick cure seem to be to goose the throttle at which point th engine picks back up its RPM's, but only for a moment.

 

[petryshyn]

Re: Yamaha outboard-RPM's fall at WOT

Does it only happen when its hot? Does it improve if you squeeze the primer bulb and keep it hard? <br />

better boating!

 

[kevinburns]

Re: Yamaha outboard-RPM's fall at WOT

To the best of my knowladge, it only happens when the motor is hot. I have not tried to squeeze the primer bulb during or after the run time, but I will try that. I do not know much about 2 stroke motors but to me it sounds like some type of fuel deprivation. i will post the results after I run her again.. Thanks

 

[clanton]

Re: Yamaha outboard-RPM's fall at WOT

Connect a vacumn gage in fuel line close to fuelpump intake side, will tell if you have fuel restriction.

 

[OBMD]

Re: Yamaha outboard-RPM's fall at WOT

What year is your 250?

 

[kevinburns]

Re: Yamaha outboard-RPM's fall at WOT

The motor is a year 2000 Saltwater Series. Thanks for any help you can provide

 

[manowar]

Re: Yamaha outboard-RPM's fall at WOT

I just bought a Yamaha 115 V4 my throttle did the same thing except it decelerated there is a adjustment for it but in the manual says dont tighten it all the way sounds like that is your problem?

 

[kevinburns]

Re: Yamaha outboard-RPM's fall at WOT

I tried that. with no movement in the position of the throttle, the engine RPM's decrease...like fuel deprivation.

 

[fbraden]

Re: Yamaha outboard-RPM's fall at WOT

I own a 1997 225EFI saltwater series Yamaha. The motor is used commercially. One year my rpm's would drop to 3700 from my 4300 cruise on a consistent basis. If I turned the motor and battery switch off for a minute and then fired it back up I was good for a while then it would happen again. Turned out to be the oxigen sensor that monitors exhaust outputs was fouled. If the sensor is giving the control unit false information, the motor can make bad adjustments that can result in such symptoms.

 

[kevinburns]

Re: Yamaha outboard-RPM's fall at WOT

fbraden...U R Right On!!!!!<br /><br />I just cleaned my O2 sensor on Saturday and she ran like a champ!!! Thanks for the help anyway.