2011 Opti 200HP, runs great except very hard starting below 50 degrees.

[Fishraptor]

I have had the Mako boat 5 years now. Runs absolutely beautiful. Starts good in summer however when temp gets down to 50 or below, just cranks. Put two new batteries in last year totaling 2000 CCA. (850 & 1150). It has new plugs, fuel, filters and such. The 200 Opti runs absolutely beautiful in summer, good acceleration, quick response, like brand new, no spit or spuddering..... just don't try to start her from 50 degrees on down. Whenever the motor did this a quick jump off the running truck has always LEAPED her to life but this past time in the fall (45 degrees) even that didn't start it. All electrical connections are SUPER clean up to motor, however I DID NOT check connections on motor. Someone said to take apart the A/B battery switch to see if it has any corrosion, this I did not do yet. One suggested a "cold temp" sensor might not be working ?? Any suggestions ? I will take to dealer if I can't figure out but that generally runs big money, rather fix myself If I can first. Note: Batteries in 21' Mako are in cabin in front of steering wheel, hence long battery cable run to Opti (maybe 15 feet or so) I doubt it can be low voltage, not with 2000 CCA of new batteries. I can run any tests that you suggest.

 

[wrench 3]

Check the voltage at the starter when cranking. It should be above 9.5V. You can check the temperature sensors when the engine is cold. The air temperature sensors and the engine temperature sensor should all read the same. Best to do it at a temperature where the starting problem is present.

 

[Fishraptor]

Thank you for the info. How would I test the Air Temperature and engine temperature sensor that you speak about above.