225 saltwater bad idle

[pontoon chief]

I am working on a 225 OX66 year 1999.I changed the the throttle cables because I thought the cables were old and starting to bind,causing the RPMs to creep up and down at idle,and at low RPMs.After changing the cables I found no change to the problem I was having.
If I start the motor and let idle back down to 800 RPM where is idles,I can watch the tach slowly climb up and down from 800 to 1400 and the throttle linkage does not move.
When I advance the throttle to 2000 RPM it will go up to 2700,2900 RPM and back climbing back and forth.
Any ideas of what is causing this condition?

 

[pontoon chief]

Re: 225 saltwater bad idle

Anyone?

 

[rodbolt]

Re: 225 saltwater bad idle

when was the last service on the O2 sensor and VST as well as fuel pumps?
also you can check for codes with the diagnostic test lamp to see if the ECU detects anything, also watch the ign timing as the motor varies, it should only change if the TPS voltage changed.

 

[pontoon chief]

Re: 225 saltwater bad idle

when was the last service on the O2 sensor and VST as well as fuel pumps?
also you can check for codes with the diagnostic test lamp to see if the ECU detects anything, also watch the ign timing as the motor varies, it should only change if the TPS voltage changed.

Thanks Rodbolt,
I will have to do some research on these items,as the boat is used daily,they might well be due.