Merc 150 EFI Won't Start

[mbrown2097]

Took boat out today and Merc started fine on first crank. I let it run for a couple of minutes and cut it off to wait on my guests. When guests arrived, it wouldn't start. It felt like the starter was spinning a little slow and would stop as soon as the motor hit at all. Just wasn't enough to get it over the hump. To me, this sounds like a battery issue. Tested battery and reading 13V and charger indicated fully charged. Battery is a Marine Master with 800 CCA. This seems a little light to me, what are your thoughts?

 

[87GTA]

Re: Merc 150 EFI Won't Start

I had a similar issue. I pulled the terminals off battery and scuffed the post and clamp till it was shiny metal again. Then put grease or something on them to slow the corrosion down.

 

[mbrown2097]

Re: Merc 150 EFI Won't Start

Looking for someone to support this conclusion as I haven't retested on the lake yet. Opened the battery box and the positive terminal was a little loose and a little corroded. I could spin it by hand on the terminal with some resistance. Also, I had 4 other ring terminals on the same post and the merc connection was mixed into the middle. I cleaned the ring terminals, and the battery posts with steel wool (pos and neg) and reattached with the merc rings first onto the battery, wrenched the nuts on tight and it started on the muffs. My conclusion is that the merc didn't have a good connection to the battery and that was keeping it from starting. Would that do it?

 

[87GTA]

Re: Merc 150 EFI Won't Start

Yes. Happened to me. Started great every single time. The day we go to launch it get it off the trailer and no start. I think it's good habit to clean connections at the start of each season.