Mercruiser 525 won't start intermittently
 

Hey folks, new to the site and wanted to see if anyone had this problem or can help. Boat starts every morning no problems. Three beep code, scanner shows fuel pressure ckt high. Cracked the water separator line and started. Any idea where to start? Haven't called Nordic yet, couldn't find anything on the web. When the boat starts no problems, just scared to shut it off, bad feeling.

Sounds like vapor lock but have never heard of vapor lock being an issue on 525EFI's. Are you running ethanol fuel?? E10 will cause vapor lock more easily.

Nope, just 91 from the pump. Thought about vapor lock.

Could be the sensor or fuel pressure is high. Don't have a 525 manual but other manuals list 2 beeps per minute with the error

525EFI Owners Manual:
http://download.brunswick-marine.com.../841196060.pdf

525EFI Service Manual Serial # 0M953620 & Above:
http://www.ibs-ny.com/freedom/Engine...e%20Manual.pdf

Id put a fuel pressure gauge on it and see where its at, fuel regulator ?

Doesnt start is vague. Does it crank over at full speed. Does it sound like it tries to fire alittle. Does exhaust smell like unburnt fuel etc.

Keep in mind, some states only sell E10 fuel on land. MO is all E10 fuel on land unless it specifically says non ethanol premium. Learned that the hard way on 100* day.

Mercury spec on octane rating for a stock 525 EFI is 87..........91 might be giving you some issues

Does it not start after a hot soak (raft up)? I'm a little confused at when the problem is happening.

My 700sci's (different induction, of course) would certainly vapor lock, almost every time we were at a raft up for an extended period. But cranking and key cycling to help push the air through the injectors would resolve until the next hot soak.

Ethanol content in fuels aggravate vapor lock due to the lower boiling point of ethanol.