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525 Vapor Lock

Old 06-18-2019, 09:41 AM
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Default 525 Vapor Lock

My port engine (525 EFI) vapor locks when I run the engine for 15 minutes or longer and then shut it off for 15 minutes. it will eventually start, usually about 5 minutes once I try and start it, My fuel pressure gauge will show 90 psi when I turn the key to prime the pump. The starboard engine show the same pressure, It doesn't matter how many times I cycle the key, I have to wait 5-10 minutes. I intermittently turn the engine over during this time. When cold it fires up perfectly, and once it does fire when warm, its instant, so the engine is not flooding out.

Before I dig into the cool fuel system and see if the heat sync compound is still around the pump, does anyone have any other suggestions. Also if I go so far, as to repack the fuel pump, I'm thinking about just replacing the entire pump incase the check valve in it is bad.

Any suggestions on this? I hooked up my Rinda, and it is not throwing any codes.
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Old 06-24-2019, 06:55 AM
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This weekend the port engine completely stopped running after getting warm and turning it off. 3 hours later, it still wouldn't fire up. Checked spark, and plugs were firing. So then I stated working my way through the fuel system, When I removed the water separator, the gasket didn't look right, so I replaced it. Went back to the helm, turned the key and once the fuel pressure reached 90 PSI, I turned the key and the engine fire up instantly. I then took the boat for a test run, to get the engine warm. An hour after turning it off, it fired up. The next day, same, no issues at all.

So, if anyone has a 525, and experiences this, change the water separator. You may be lucky and have it solve your problem.

Last edited by endeavour32; 06-24-2019 at 08:10 AM.
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Old 06-24-2019, 07:28 AM
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Thanks for the tip.
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Old 06-24-2019, 07:38 AM
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Our port motor 500efi vapor locks...we have done two things to help with the issue.

1. Keep lid open after hard runs to cool engine compartment.

2. During restart bump throttle a little to push vapor thru the fuel system

usually with both of these we can get it started without issue.
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Old 06-24-2019, 08:12 AM
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I tried keeping the lid open, running the blowers, as well as the throttle in different positions, nothing worked. I'm hoping it was some, one off situation, with the fuel/water separator. You can find lots of posts on the 500 EFI having these issues, but very few with the 525 EFI.

Last edited by endeavour32; 06-24-2019 at 03:15 PM.
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Old 06-24-2019, 08:42 AM
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Endeavour, you may want to check your regulators. 90 psi of fuel pressure is way too much. Have you verified it’s that much with a scanner? Strange that both motors are showing that much psi
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Old 06-24-2019, 08:52 AM
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The only time it's 90 psi is when I cycle the key (engine not running), as soon as the engine starts, it drops to 45 psi and stays there no matter what the RPM is. Both engines do the same thing. 90 psi, with a cycled key and 45 psi once started. I've not verified these numbers with my scan tool.
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Old 06-24-2019, 11:38 AM
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Ok sounds good, I thought you were 90 while running. I had a bad regulator on one of my old 525’s, motor wouldn’t run for chit, 80 plus psi on the gauge
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Old 06-16-2021, 12:03 PM
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BUMP on this thread.

I believe I had the same problem this past weekend as OP described. Both my 525's flopped at the exact same time after a run, then anchored for cpl hours, fired up fine, past the no wake zone, throttle down, about 3000 RPMs, the both fell flat on their face. Wouldn't start. Fired up and idled fine on trailer at ramp next morning and 42ish fuel PSI.

I too will be changing my Fuel/Water separators and doing the various tips and tricks that many describe given the increase in Ethanol in today's fuels.

Thanks for the intel.

Ian

Last edited by imartin; 06-16-2021 at 12:12 PM.
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Old 06-16-2021, 01:19 PM
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it's for my 350s, but most should apply.

Intermittent No Start - but then works fine - then doesn't

TLDR: replaced IAC, replaced fuel pump, replaced fuel pressure regulator.

Engines now start much easier, key only, hot or cold. Start and stay running.
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