Finding fuel cooler check valve

Stuartvaguy

Cadet
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Jul 6, 2020
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I had recently posted about a stall after the boat is turned off that I've now determined is vapor lock on my 1999 mercruiser 5.0 efi serial number 0l340610. In addition to wrapping the fuel lines and allowing it to idle for a few minutes before shutting off, I am interested in adding the check valve that will prevent hot water from going back out to the fuel cooler after shut down. It is my understanding that they were installed stock on later mpi engines. I've also read one instance where someone found an aftermarket part but I'm not having any luck finding it. Can someone please guide me to this part? Thank you!
 

achris

More fish than mountain goat
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May 19, 2004
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27,468
You don't need it. The impeller acts as a check valve. Water can't flow passed an impeller that's not turning...

Chris...
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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I seriously doubt you have vapor lock
 

Stuartvaguy

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Jul 6, 2020
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It only stalls or fails to start after it's been run planed off for a while. There are a lot of articles and posts about how vapor lock is quite common due to the closed in space and poor ventilation. Also, I experience it much less frequently when running higher octane fuels which have a higher boiling point. From what I've read the check valve prevents the hot water from coming back to the fuel cooler after the boat has been turned off lessening chances of vapor lock.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
51,351
It only stalls or fails to start after it's been run planed off for a while. There are a lot of articles and posts about how vapor lock is quite common due to the closed in space and poor ventilation. Also, I experience it much less frequently when running higher octane fuels which have a higher boiling point. From what I've read the check valve prevents the hot water from coming back to the fuel cooler after the boat has been turned off lessening chances of vapor lock.

you dont have vapor lock. you have a fuel delivery issue, most likely a plugged vent or a plugged anti-siphon valve. check your fuel pressure.

if you crack your fuel cap when this happens and you hear hissing your vent is plugged

what ever articles you are reading are wrong...... boats dont suffer from vapor lock. if your bilge got hot enough to suffer from vapor lock, you would probably be burning the gel out of the bilge and have other issues.
 

Stuartvaguy

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Jul 6, 2020
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Ok so I know my anti syphon was contributing and I replaced it with open tube to test while one is on order. I can't locate a vent so I'm assuming that the vent tube is connected in with the cap and main fill spout. So, I figured the fact that this cap says waste can't be go and I've ordered a cap. I was getting my info also from a mercruiser technical bulletin but I keep hoping it is not vapor lock. I loosened this cap some as I was resting but perhaps it was still wasn't enough. As far as testing fuel pressure, I've never done this but perhaps I can read up on how to go about doing this. There are just never any problems with running until there motor is turned off so that's what led me to vapor lock.
 

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