2005 6.0 won't start after sitting 3 hours

[TigeDuner]

Where is the water fuel separator located? Is it the unit with the two lines coming out of it that feed the fuel filter and has the yellow sticker that says "this is not a step"???

[TigeDuner]

we have found that it is a lot easier and quicker to bleed off the fuel and air then to pour water on the motor. We bleed it into a crunched up water bottle and it has worked so far...

[brose]

I'm having identicle issues with a 2005 24V with the Marine Power 380HP 6.0L. Starts up great in the beginning of the day. But after riding hard, then sitting, it won't start. Turns over just fine, but never catches. It's happened to me 4 times in the last 2 weekends.

I do have a heater on my boat and would like to see steps to do the entire mod. Please post here or PM me if you have step by step details. Thanks!

[TigeDuner]

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

Good luck-take lots of pictures. I spoke to Dom today and he walked me thru it, but pictures will confirm his directions. Where did you get the thermostat and which one did you get?

[evil0ne]

Good luck-take lots of pictures. I spoke to Dom today and he walked me thru it, but pictures will confirm his directions. Where did you get the thermostat and which one did you get?

I just paid Dom for all the parts. I think it was $30 total. Forgot to also mention that I installed the parts the weekend they were having the boat show in Florida. Dom gave me his cellphone number and when I called to clarify something he was at dinner with his family and he took the few minutes to help me out. Great guy.

[kbunch]

Ok! Mod complete. Did not really see a cooler temperature reflected on the gauge but I really think the engine is running cooler than before plus after "Guys lake day" which was 6+ hours of boarding and surfing with more than one 2 hour plus shutdown. Before the mod I have no doubt we have had to deal with vapor lock. Yesterday it started EVERY attempt which was AWESOME! I took pictures and will post soon as I can get them off my camera.
Thanks everyone with the advice and Dom for the idea.

[TigeDuner]

You sold me. I will contact Dom next week for the parts, unless I can find the here in Tucson. We do not have many boat dealers in the desert.
Thanks and get the pictures up so I can see what I need.

[SPBFAN]

Put a fuel Gage on it. EVILONE had this problem. If the needle is not holding steady at 58 PSI or a there about and it is vibrating or wiggling the slightest bit you have a small leak in the fuel system. When you let it sit the fuel flows out of the rail into the tank. Then air gets into the rail and vapor locks because of the hot soak. Also check and make sure your shader valve is tight and in good shape. Let us know the result ls.

[TigeDuner]

Where is the thermostat housing located on the motor and did you loose a lot of coolant during the exchange?

[Joeprunc]

Put a fuel Gage on it. EVILONE had this problem. If the needle is not holding steady at 58 PSI or a there about and it is vibrating or wiggling the slightest bit you have a small leak in the fuel system. When you let it sit the fuel flows out of the rail into the tank. Then air gets into the rail and vapor locks because of the hot soak. Also check and make sure your shader valve is tight and in good shape. Let us know the result ls.

What you described here sounds exactly like a faulty fuel pressure regulator. I've mentioned this before, but most people say its not the issue. I've always thought Vapor Lock happened with a carb system not EFI. But then again, I'm not a mechanic.

[chpthril]

What you described here sounds exactly like a faulty fuel pressure regulator. I've mentioned this before, but most people say its not the issue. I've always thought Vapor Lock happened with a carb system not EFI. But then again, I'm not a mechanic.

Vapor lock became an issue on carbs when we started using 195* thermostats, so the auto industry crossed to EFI to prevent it.

Here is why: Just like coolant in a radiator boils at 212*, fuel will boil also, once it gets hot enough. For a radiator, we use a pressurized cap to seal the system and raise the boiling point. For fuel, we use a sealed, pressurized fuel injection system to achieve the same thing. We use a high pressure pump to build the pressure in the lines and fuel rail. Once we have pressure built, the boiling point is raised and the fuel doesn't boil and stays as a liquid in the system.

Now, with boats, such as the Tiges with the closed-cooling 6.0, even with a fuel system holding pressure, the temp under the engine cover has been known to get hot enough and boil the fuel, thus creating vapor-lock. For those that dont know, vapor lock is nothing more then liquid fuel boiling in the lines and rail and becoming a gas (vapor). This gas cant be effectively pressurized, nor can it be pushed through the system and delivered to the cylinders as liquid fuel can. Once we have the vapor in the system, the engine will not run, or will barely run if it does start. The short term cure is to lower the temp and get the fuel to condense back to a liquid. The long term fix is to find the root cause.

With the 6.0's, we know this has been happening from the beginning, so it seems to be a temp problem, not a leaking down fuel pressure problem. All avenues need to be looked at, but I would start with what is known, and then move on to the other possibilities. Other causes of vapor lock: Week or faulty pump(s) causing low fuel pressure to start with, leaking injector, leaking regulator, leaking check-valve in pump. All these can be diagnosed with a fuel pressure gauge. Higher then normal engine temps can lead to vapor lock, even though the fuel system is intact. This could be caused by a lean air/fuel mix, incorrect timing, excessive loads (ballast or Zad's gf's), faulty/wrong thermostat, impeller/pump housing, circulation pump, restriction in the raw water pickup system, low oil level, poor heat transfer between the cooling coil and the filter/pump housing.

Now, if you have any other engine other the the closed-cooling 6.0, I would look at all the other things noted above, and not worry about the cooling system mod. For the 6.0, start with the mod and go from there. If you have access to a fuel pressure gauge, it would not hurt to throw it on and just see.

[Joeprunc]

That makes a lot of sense Mike. I appreciate the explanation vs the "you are wrong" approach.

[ajholt7]

Zad's GF's cause vapor lock?

[chpthril]

Zad's GF's cause vapor lock?

Have ya seen them heavy loads make the engine work harder

[ajholt7]

Have ya seen them heavy loads make the engine work harder

Well, I knew they caused excessive fuel consumption.