250 OX66 Cold Start Idle

[flyin fisher]

Motor is a 2001 250 OX66 with 500hrs. All maintenance has been performed religiously alternating between 100 and 200hr services in accordance with the owners and service manuals. I'm 50 hrs into the last 200 hr service, which included new VST and new LP diaphram pumps. I put the boat in the water yesterday and when the motor started, it would only idle around 600 rpm instead of the usual 12-1400 rpm when the motors cold. The motor finally warmed up and ran good so we went fishing and never had any more trouble with it. The next morning I start the boat to load it on the trailer and the same thing happened, no cold engine idle up. When I got the boat home, I waited about 4 hours and put the winky blinky on and it started right up and idled to 12-1400rpms, with the normal codes of 33 followed by code 1. Any ideas?

 

[rodbolt]

Re: 250 OX66 Cold Start Idle

if the under hood temp was higher than 113* it will briefly rev to about 1100 at startup but about instantly go back to about 650.

 

[flyin fisher]

Re: 250 OX66 Cold Start Idle

I initially put the boat in the water at 7am down here at Topsail Beach, the motor temp couldn't have been over 70 degrees. The boat had not been run for about 5 weeks before this. I was wondering if I could possibly have a bad temp sensor?