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Mercruiser 525 won't start intermittently

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Mercruiser 525 won't start intermittently

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Old 09-09-2020 | 08:25 PM
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Default 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.
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Old 09-09-2020 | 09:20 PM
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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.
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Old 09-09-2020 | 09:24 PM
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Nope, just 91 from the pump. Thought about vapor lock.
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Old 09-10-2020 | 07:00 AM
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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
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Old 09-10-2020 | 09:28 AM
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Originally Posted by AllDodge
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

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Old 09-10-2020 | 10:14 AM
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Id put a fuel pressure gauge on it and see where its at, fuel regulator ?
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Old 09-10-2020 | 10:33 AM
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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.
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Old 09-10-2020 | 12:10 PM
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Originally Posted by TerryP
Nope, just 91 from the pump. Thought about vapor lock.
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.
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Old 09-10-2020 | 12:36 PM
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Mercury spec on octane rating for a stock 525 EFI is 87..........91 might be giving you some issues
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Old 09-10-2020 | 12:59 PM
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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.
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