08 Merc 350mag/B3 crank but no start, starts after sitting for week

[63a16p]

2008 Searay 240 350mag/B3 110 hours, Eng SN 1A066891, all freshwater use

I purchased boat last summer with 96 hours, Cool Fuel module replaced just before purchase due to freeze damage

Used boat Thurs/Fri/Sat last week. No issues Thu/Fri, ran great. On Saturday, boat ran great for first hour then stopped to swim. After sitting for approx 30 minutes, tried to start. Engine cranked fine but no start. Tach showed approx 150rpm while cranking. Tried starting boat (intermittently) for approx 30 minutes before getting tow back to ramp. Attempted start after tow but still no luck. Loaded boat on trailer and put back in storage. I also scrolled through Smartcraft indicators - all normal.

Today (1 week later), I went to boat with fuel pressure gauge to check FP. Key on - fuel pressure immediately jumped to 40 PSI. I tried starting and boat started immediately on cranking.

I'm glad the boat will start but need to determine what happened to prevent a reoccurrence.

Any ideas with regard to additional diagnostics will be appreciated.

 

[pursuit2460]

I had a similar problem. I took it out, ran perfect. Got to my destination and about 30min later decided to leave. Crank but no start. Let it sit for about an hour and started right up. I posted on here about my FP issues and I came to the conclusion that it was vapor lock in the fuel line. My fuel system is a fuel pump mounted to a brass pipe that the fuel flows through while water also flows through to cool it. Different system than yours(old style) but works the same, cools the fuel. If I am not mistaken, I did a whole cleaning of the entire cooling system and installed a new water pump. I also replaced the FP because it was sounding rough. The pipe the FP attached to needed cleaning and so did my heat exchanger. I haven't had any issues since with vapor lock. I also recalled issues with the paint on those CF pumps but they were supposedly fixed. Sorry I cant be of more help, this is my first I/O and I am also learning as I go along.