1998 210 Signature BR with 5.0...
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06-28-2020 10:48 AM
1998 210 Signature BR with 5.0 Mercruiser EFI, was on the lake and had stopped for lunch for approximately 30 minutes but when finished lunch I started motor with no issue only it stopped within 5 seconds. On every subsequent attempt to start motor it would fire and immediately cut off. Interestingly while being towed to dock, I attempted to start motor and it started and ran fine all the way to dock never any issues prior to this. At dock I stopped and successfully restarted it once while loading. Has anyone experienced this issue? What should I do preventively before our next outing?
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06-28-2020 11:44 AM
The symptoms sound like heat soak vapor lock.
If this is the problem, then Mercruiser has an expensive solution, adding a low pressure pump before the fuel pump to "burp" out the vapor, permitting the engine to start, hiding the problem.
The engine compartment is insulated, to contain audible noise, for better experience when boating. That insulation also contains heat, causing the engine compartment temperature to spike when the engine is shut down, frequently the cause of heat soak vapor lock, with the conditions described.
On my boat I designed and installed a thermostatically controlled high volume heat exhaust system that maintains the engine room temperature and has eliminated the problem.
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06-28-2020 11:57 AM
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06-28-2020 01:53 PM
Another test is to connect a fuel pressure gauge to the fuel rail. If the pressure is abnormal during the problem, then it is definitely heat soak vapor lock.
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08-09-2020 08:47 PM
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08-29-2020 09:02 AM
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08-29-2020 01:26 PM
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08-29-2020 04:53 PM
Was the boat stopped for ~1hr w/ the engine compartment open to determine if the problem exists, results?
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08-30-2020 01:56 PM
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10-11-2020 09:34 AM
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10-11-2020 12:04 PM
My experience is that the OEM blowers had zero effect on heat soak vapor lock.
Those blowers must suck from the bottom of the engine compartment, to draw the heavier than air gasoline fumes, if they ever exist.
But, heat rises and the engines have a huge thermal mass.
Once the engines are stopped the cooling water flow also stops, so the engine compartment temperature rises.
On my custom thermostatically controlled heat exhaust system, I draw warm air from the top of the engine compartment to maintain a constant temperature.
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10-11-2020 12:39 PM
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