2005 6.0 won't start after sitting 3 hours

[brose]

Curious, does the thermostat mod make the temp gauge read inaccurate?

[TigeDuner]

According to those who have done the mod, their gauge still reads about the same.
I ordered the thermostat and hope to change mine in the next month or so. In the mean time, I removed the port vent hose from the vent to vent the engine compartment better. I also start the engine every 30 minutes if we are stopped for any long period of time. This worked fine last weekend with no issues, but we didn't rest much. I also changed the fuel filter with the internal regulator since I have about 450 hours. Still need to change the fuel water separator, which I have been told is a bitch. we will see.

[jsz]

I have a 2002 Merc 350. I was having the same symptoms and a new fuel pump fixed the problem. Just another possibility for you...

[loudelectronics]

Heres my take on the issue cause I go through it every weekend. When I stop the boat for a period of time after use I will lift the cover on the motor. Problem solved.

Sometimes I forget to do this and have to go right after the problem itself. On the black plastic fuel line on the driver side of the motor under the coolant line there is some sort of regulator. If you pull the compressor off the regulator while holding the regulator the pressure will be released. This thing does not vent, even though there is a vent on it for some reason. I then put it back together and I am away. Takes 15 seconds to do. Or else you can pour cold water on that same peice and it will turn over for you pretty quickly.

[loudelectronics]

According to those who have done the mod, their gauge still reads about the same.
I ordered the thermostat and hope to change mine in the next month or so. In the mean time, I removed the port vent hose from the vent to vent the engine compartment better. I also start the engine every 30 minutes if we are stopped for any long period of time. This worked fine last weekend with no issues, but we didn't rest much. I also changed the fuel filter with the internal regulator since I have about 450 hours. Still need to change the fuel water separator, which I have been told is a bitch. we will see.

Just sock the Seafoam to your gas tank. It will clean out the water seperator. I have 400 on mine and have yet to change it. Fuel Filter either. Seafoam in every tank, two cans if I use jeri cans cause I know there is always water in them.

[chpthril]

Heres my take on the issue cause I go through it every weekend. When I stop the boat for a period of time after use I will lift the cover on the motor. Problem solved.

Sometimes I forget to do this and have to go right after the problem itself. On the black plastic fuel line on the driver side of the motor under the coolant line there is some sort of regulator. If you pull the compressor off the regulator while holding the regulator the pressure will be released. This thing does not vent, even though there is a vent on it for some reason. I then put it back together and I am away. Takes 15 seconds to do. Or else you can pour cold water on that same peice and it will turn over for you pretty quickly.

Do you have a pic of what you are venting or pouring water on?

Fuel injection is not supposed to "vent" anything. A reduction in pressure increases the chance of vapor lock, that's one of the reasons why we use EFI. If the fuel system is holding pressure like it should, the only other thing to do is reduce the engine temp or under-hood temp. It could be as simple as increasing the raw water flow to the fuel cooler.

[kbunch]

I have finally posted the process I followed to modify my engine after talking with Dom. you can follow my project in the "how to" section:
http://www.tigeowners.com/forum/showthread.php?t=13252

[dogbert]

I have a similar problem on my Mercruiser. I run the blower for a few minutes to cool down the engine compartment and that usually takes care of it.

[dom w. forte]

I have finally posted the process I followed to modify my engine after talking with Dom. you can follow my project in the "how to" section:
http://www.tigeowners.com/forum/showthread.php?t=13252

What the mod does is force more coolant to go through the heat exchanger instead of recirculating it back through the block, this was an emissions motor by design which is made to get hotter quicker and stay that way.
When modified all computor stradigese are better and you will normally notice an inprovement in performance, there will be no noticeable change in the dash guage reading , but if you hook a lab top to the dignostic data you will see the engine temp. stays at 158 to 160 steady, idle or under load, my 2004 has 1000hrs of hard load and has not failed yet.

[kbunch]

I am a believer and wanted to thank you Dom! The mod went exactly as you described, and like I said, not a single vapor-lock issue since~

[TigeDuner]

We had no trouble with the vapor lock issues this past weekend after the disc was installed. Many thanks to you Dom, and to you Kevin, for helping me through this. I will add a few pictures to your how to, as well as a few comments to help those along that are dealing with this pain in the *** issue.
We can now enjoy our down time and not have to worry about starting issues after a few cold ones and a rest.

[TigeDuner]

We also did notice a slight drop in temp on the gauge, but the lake temp was 88, so we were all surprised to notice anything.

[Heisenberg]

How I deal with it is easy. The motor is in a readily accessible "doghouse" in the middle of my stern. After I stop the engine and plan on sitting for any length of time, I grab an bottle of ice water from the cooler, place it on the fuel filter atop the engine. Before I start, I remove it. Works every time.