2005 6.0 won't start after sitting 3 hours

[TigeDuner]

We have experienced this problem about 6 times over the past 3 years and this past weekend it happened twice in the same day. The engine runs fine all day as long as we start it up shortly after we turn it off to bring someone in the boat or change boarders. Let it sit for a couple hours and it cranks,catches, and stops.
This is a 2005 6.0 380hp Marine Power in a 24V. Boat has 450 hours and no problems to date. We believe it was fuel related so we removed the plastic cover and found the fuel bleed off shrader valve. We bled out the fuel and found a lot of air in the line.
Turned the key and it started up.
We did the same thing later in the day and it started up fine. The next morning and the next day the boat was fine but we did not take long breaks, maybe only 1 hour or so.
It was 100+ and the water temp was 90. The engine temp was at 185+/-.
The fuel filter has never been changed. This was our only guess. It is mounted on the top of the motor and has two lines in and 1 out.
Any thoughts guys?????

[chpthril]

Vapor lock! Have you not had the fuel system mod done on yours?

Do a search, I know Dom @ FIC has posted quite a bit of info on this.

[TigeDuner]

I have not made any engine mods at all. I will search the site and see what I can find. Thanks.

[TigeDuner]

No luck Cheep, I could not find the link you were talking about. I did see that many Tige owners do have the same problem. One thread said that the rubber fuel line from the tank to the pump was replaced and that solved the problem. That's a possibility but I really don't want to remove the floor and back seat if there is a fix all mod to be done.

[TigeDuner]

More discussions = more ideas. One thought is that since the fuel filter is mounted on the top of the motor, when the motor is shut down, residual heat from the motor heats the fuel in the filter for the vapor lock during a two hour swim and beer session. The filter can not be relocated due to the steel lines in and out, but it could be wrapped. Thoughts???

[chpthril]

This was a known issue on the 6.0 and there is a fairly simple mod to improve fuel cooling and prevent vapor lock.

[TigeDuner]

Are you going to keep it a secret????

[evil0ne]

If it is Dom's thermostat mod it didn't work for me. It is a great idea to do no matter what but it wasn't the silver bullet I have been searching for.

If that is what you're referring to, here is my recollection of what Dom is doing (I have also done).

1) Replace stock 160* thermostat with thermostat from 5.7L (140*)
2) By using a toggle bolt and a washer close off one of the chambers making it flow similar to the 5.7L motor

He explained that in the trucks these motors are designed to run hotter for emissions but its not so great in the boat. Again, interesting mod but didn't solve my similar issue.

[TigeDuner]

So how how do you deal with the vapor lock?

Did changing your fuel filter on the motor help?

[solaidrider667]

Last year I had vopor lock issues with my 6.0 and after I did the t-stat toggle bolt mod it has been perfect.
Also the fuel filter with 450 hours that has not been changed could play a role in your issues.
Good luck

[lohe]

I got vapor lock for the first time last weekend... I had never had it happen before :/ If it happens again I will start looking into some sort of fix.

[TigeDuner]

Tell me more about the mod. I tried to get thru to Dom this morning and the answering machine was in loop mode.

[TigeDuner]

Fuel filter is GM 10299146 or Wix 33737. Got the Wix for $35 on Amazon which is half of the GM prioe. The filter has an internal regulator in it that cranks up the price. Due to be changed at 450 hours....

[kbunch]

I have been having the same issues and am going to complete the mod tomorrow assuming my new stat arrives. I can explain the procedure if you want to PM me. I will try to post pictures of my mod later this week. One other thing, I DO NOT have a heater on my boat, if you do there is a couple other steps you have to take and I do not know what they are. I can say I tried a new Marine Power stat, flushed all fresh water and internal systems, and found myself pouring water over my pumps and rails in order to get underway, which sucked! now I am going to join the smart modified 6.0 owners club..... wish me luck

[sincity]

i had the same problem, i took it the dealer here in vegas two years ago when i had the problem, showed him DOM'S fix they said they didnt think it would work, they called the factory, factory said change the t-stat to a lower temp. well that didnt work, besides the 6.0 closed cooling system is going to operate at 175 to 190 degrees no matter what, at least on my boat it does. so i have just lived with dumping cool water on the fuel pump when it does vapor lock, untill this year, i decided to do the service on my boat myself for this season, after changing the water fuel separator, i havnt vapor locked once this year, and it has been extremely hot at lake mead this year.
sincity