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Vapor lock?

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Wasabi757

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I’m finding that if I run at cruise speed (high power setting) for, say, a hour or so, then shut down for about a hr, that my boat will start and idle for maybe a minute then die. It then takes many attempts to start the engine but does eventually start and runs perfectly fine afterwards.I’m thinking this is classic vapor lock. Contributing conditions are high ambient temperature and ethanol in the gas, which I will no longer be using. I will probably alter my driving habits by reducing power for several minutes to idle before shut down and opening the engine hatch to allow the e compartment to cool.
Anybody else experience this? If so, how did you address the problem?
2005 Ebbtide 5.7L (350ci)
 
if you shut it down after a a long run, its very likely you are having vapor problems...especially if you have a small and tight engine room....

a cool down of several minutes, at a high idle, in neutral can only help...as does opening the hatch. Going with ethanol free gasoline will help but not eliminate the issue...

inadequate ventilation is the main cause on most small boats...few hull makers satisfy the engine maker's requirements for max operating temperature...most don't want to see anything over 150 deg F, in the engine room, over the top of the engine...
 
makomark said:
if you shut it down after a a long run, its very likely you are having vapor problems...especially if you have a small and tight engine room....

a cool down of several minutes, at a high idle, in neutral can only help...as does opening the hatch. Going with ethanol free gasoline will help but not eliminate the issue...

inadequate ventilation is the main cause on most small boats...few hull makers satisfy the engine maker's requirements for max operating temperature...most don't want to see anything over 150 deg F, in the engine room, over the top of the engine...
Click to expand...
Yes, I do agree we have a vapor locking condition. As soon as my existing fuel supply gets close to empty, I will refuel with gas that is ethanol free. I’m also going to be monitoring the engine compartment temperatures as well as keeping tabs on ambient air temperature while running around on the lake. Opening the engine cover hatch and venting out the heat coming off the engine has got to be a step in the right direction too. Perhaps a 12 volt fan/blower can be added to help get the hot air out as well.
 
You should already have a 12-volt fan/blower installed, required for boats with gas tanks in an enclosed compartment.
 
I do have a blower. Traditionally, I would run it only before starting the engine. I think I will run it while underway and leave it on after shut down. My guess it doesn’t use a lot of battery to run it after shut down. I’m also going to start monitoring the temperatures inside the engine compartment
 
I read that shortening the fuel line as much as possible could help prevent vapor lock? I've got a 98 Searay with the 5.0 Merc. The fuel line runs to the side of the compartment through a bracket and then loops back to the fuel pump. Guessing that is for a reason???
 
I'm thinking about what i can do to reduce/eliminate vapor lock on mine too.
Has anyone looked into hooking up a 3-port fuel filter and dumping the vapor outlet port back to the tank? I'm also thinking that replacing the steel line with rubber between the pump and the carb might help as well (or even insulating the steel line might help too).
I tried searching for links on this topic but didn't come up with much.
Vapor lock is common on carburated cars and these ideas have worked for many people.
 
I installed a pair of 3x8 ( hole size) louvered vents in the engine box on either side of the engine at the carb location.
 
Like Capt Bob suggests, air is your friend.

I don't think your car ideas will work on the boat...its engine compartment is not open to the environment at the bottom so ventilation is the only option...some are happy with a passive setup - some need more.
 
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