Mercruiser won't Keep running!

Full House

Recruit
Joined
Jul 8, 2009
Messages
2
I have a 2001 Bayliner 2452 with a 5.7 liter 250HP Bravo II having what I believe is some sort of fuel issue. My boat typically has been trailored for the last few years which means sitting for the most part. For the last 3 years it mainly gets used off the west coast of Washington during the salmon season in the summer and doesn't get used much otherwise. I finally got a slip to moore the boat to get more use out of it. I have never had a problem starting and running this boat even after a year of sitting and this year was no different. While on the trailer I started the engine (first crank) and it fired right off. I ran it for approx. 1hr. with absolutely no problem! I have an 80 gallon fuel tank which had approx. 30 gallons of fuel from last year, which I added stabalizer to after parking it and a marine fuel dryer this year prior to starting. On my way to launch it I added another fresh 50 Gallons of shell premium fuel and I was off to the launch. When I launched her last week I started the engine as always, fired right off, ran for 5-10 seconds and died. I tried this several times more with the same results. I had realized that I had not changed the water seperator filter as I always do each season and figured this was my problem. Tried starting again and had the same results. Now confused by the fact that it had ran perfect at the house and not in the water I decided to do more investigating. I pulled the flame arrestor off of the 2BBl Rochester carb and removed the throttle linkage to allow manual operation of the throttle. While having my wife crank it over I worked the throttle and as long as I kept pumping the accelerator pump it was getting fuel enough to keep running but it would also get to a point where the rpm's would raise and it would just die as if it were starving for fuel. My next thought was possibly a sticky float or needle valve. So I got a rebuild kit and completely rebuilt the carburator. I re-installed it with the same results. So whats left? The fuel pump, Right? Well I pulled the line off the carb, again and hooked a hose to it and cranked it over, the pump was spitting fuel out at a good rate and with pressure. I don't have a fuel pressure guage to test the actual pressure but even if I did i'm not sure what it should be. If this were a throttle body or EFI system that needed say 16psi to maintain proper operation I could see it being maybe the fuel pump but this is carburated bowl system where as long as you supply enough fuel to keep the bowl filled I would think that should be sufficient especially at an idle. Am I flawed in my theory with these newer carbs? Back in the day when I used to build motors in the garage we hugg gas cans from the roof and allowed gravity to replenish the fuel in the bowls of carters or quadrajets. I would appreciate if anyone could throw any ideas or sollutions my way.

Sorry this was so long
Thanks Bob
 

bamadave

Petty Officer 1st Class
Joined
Mar 24, 2005
Messages
391
Re: Mercruiser won't Keep running!

Did you saok the carb body in cleaner when you rebuilt it or just throw the parts in?
 

snoski

Seaman
Joined
Aug 23, 2008
Messages
69
Re: Mercruiser won't Keep running!

It sounds like what mine was doing when I had a coil going bad. Be sure to replace with the correct one or you will be buying another soon. Ask me how I know this...
I would also check you tank vent line to make sure it is clear and venting your tank properly. Dirt dobbers and other insects love to get in there and build nests when the boat sits at the house for long periods of time...
Good luck...
 

Full House

Recruit
Joined
Jul 8, 2009
Messages
2
Re: Mercruiser won't Keep running!

bamadave,
I did soak the carb and blew out all the ports. I have made sure the air vents on the fuel tank are clear as well.

Thanks
 
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