fuel problems? maybe?

Hey all,
I have a 2004 Merc 496 serial# 0w313044. How do I trouble shoot the Fuel System?

The engine starts every time when the engnie is cold. Once hot if I shut it down for 1hr or so then try to restart this is when I have the problem. If it starts I have to get moving or it dies. Once dead I have to open the engine bay and let it cool 15 or 20 minutes, then it will start. (Vapor Lock?) Since I have had this boat (2 years) this is the way it has always been. I can shut it off for 2 or 3min and it will fire back up fine any longer it is a no go. This year a new problem is here. After the first start of the season, I got gas which is a 10 minute ride, I shut it down and fueled up for about 10 minutes. It cranked up fine, on my way home at 3000 rpms the engine lost power and died. Not a abrupt stop, no coughing, it just slowed down and died. The next day it crank up fine. I did a "italian tune up" (WOT for about 10 minutes, at 56mph and 30+ gal/hr) twice during my run I had power sags for 1-2 seconds, but it came back strong. Since finding this forum I have new fuel filters ordered, however there didn't seam to have much junk in them.

What do you all think? Vapor lock? Low pressure pump? Bad Luck? My wife's answer to my woe

Thanks to all

Re: fuel problems? maybe?

OK new water separator was installed. Also I put a priming fuel bulb inline right after the tank.
Good news when is dies I manually prime and the engine starts, bad news I have lost full power?

Any ideas?

Re: fuel problems? maybe?

Vapor lock is a definite issue on some boats I have this problem. If you run around then stop for thirty or more minutes its like there is no fuel. Opening the engine cover and letting it cool down while you fend off the very helpful and friendly boaters coming to your aid is the only answer to make it run. What I have found is if you let the motor idle for a couple of minutes while running the bilge blower it cools it off enough back there to avoid the problem. Stopping long enough to retrieve a skier or tuber is never a problem only stopping for extended time after running a long time. There is a Mercruiser service letter that addresses this. If you search Vapor Lock you will find it.

Here is the service letter http://www.boatfix.com/merc/Bullet/99/99_07.pdf

Re: fuel problems? maybe?

Fuel line sucking air? bad anti-siphon valve, clogged pick up in the tank?

Engine carbed or injected? Sterndrive or inboard? Magnum, Horizon or HO?

Chris........

Re: fuel problems? maybe?

achris said:

Fuel line sucking air? bad anti-siphon valve, clogged pick up in the tank?

Engine carbed or injected? Sterndrive or inboard? Magnum, Horizon or HO?

Chris........

Click to expand...

Hey Chris, I have a Sterndrive, bravo 3, Injected. And I have no clue about the Magnum/Horizon/HO

Is the anti-siphon the check valve in the Fuel pump body?

I do have a fuel cut off solenoid which has a by-pass switch, and I tried it both ways.

Re: fuel problems? maybe?

Anti-siphon valve will be in the fuel line, somewhere close to the fuel tank...

With all that rubbish in the lines between tank and engine... I'd be using a 5 gallon remote tank (outboard style) and plumbing it directly to the engine mounted fuel filter... If the engine still runs crap, at least you've ruled out the fuel supply.... If it runs correctly, you know it's in the fuel delivery somewhere.... Basic fault-finding technique... Divide and conquer...

Chris.........