Losing power?

[steelboss]

I recently purchased a 95 SeaSwirl ski boat w/<br />an OMC 3.0l I/O motor. The boat starts and runs<br />fine intially. It will take off and hit top <br />speed with no problems, but after 30 sec. to a<br />minute the RPM's slowly start to drop until the<br />boat stops. You can put it back in neutral and<br />take off again just fine for about a minute and<br />it falls back down.<br /><br /> Any ideas on what the problem could be?

 

[hoot]

Re: Losing power?

i would look at fuel system. filter, pump, carb float level (if not fuel inj'ed) and fuel tank vent. next time it happens, remove the gas tank cap and try it. my experience has been that if it is igniton, it takes longer to happen and things have to cool off before normal operation.

 

[gisxr750]

Re: Losing power?

my boat is doing the same thing i am in the middle of replacing the low pressure pump we will see? thats if you got efi i will let you now my results but the pump is on back order!! just my luck

 

[steelboss]

Re: Losing power?

Mine has a 2 barrell Holley on it.<br /><br />I've checked the fuel filter and cleaned the vent, still doesn't run right. Can someone <br />explain how I would check the carb. float level,<br />or the pump?<br /><br />Thanks

 

[hoot]

Re: Losing power?

fuel pump pressure test requires a pressure gage and some fittings to attach to the fuel inlet line. a volume test can be as simple as pulling the carb inlet line, removing the coil wire so boat doesn't start, and holding a jar so the fuel can run into it as someone turn the key for several seconds and see how much and how smoothly the fuel enters the jar. my carb is a rochester and its float has two measurements, one fully down and one up. you will need the measurements and from what reference they are taken (should buy a repair manual). another thought, your fuel filter may be restricting flow at high demand level. you could remove filter and see what happens or just replace yours anyways. sometimes they can restrict flow and look ok visually. and just how does your boat shut down? does it spit and sputter and completly shut off or does it suddenly just slow down and idle? my experience has been that a jerky, sputtering type of stall with complete engine shutoff can be ignition and the later is fuel.

 

[rml]

Re: Losing power?

crazy as this may sound, I had a similiar problem but there were some noises (sort of a banging sound) and a temperature increase (155/160 -> 185/190) that happended just before losing power then dying. Shutting it off (1989 5.7L & Cobra Leg), checking oil (OK), total shutdown time of 45-60 seconds then restarted -- no problem. Didn't happen everytime out, just a few times throughout a season.<br /><br />I checked the fuel, ignition and lubrication systems and found nothing out of the ordinary. However, what I did find during a bellows change that is of interest...was the exhaust flappers had a meltdown at some point, fell off their hinge pins and both had made their way down the Y-pipe but were still fairly intact and were too big to exit the exhaust port on the transom plate. My theory is that every so often, the defunct flappers would pop upright and block the exhaust port while running, causing the temperature increase then resulting in a stall ... a la the ol' potato on the tailpipe trick...once the engine shut down, the flappers would fall back down, clearing the blockage. Gravity, horizontal/vertical/diagonal motion of the boat, boat speed and exhaust pressure were the only variables ...can't prove it to be the cause but I can say that it hasn't happened since installing new flappers and removing the old ones.<br /><br />Anyway, your 3.0L has one exhaust pipe and one flapper, checking to make sure it is still there is easy, if it's missing it means that it was removed or it melted and fell down the pipe...if it fell down the pipe, well that's another topic entirely. Good luck.<br /><br /> --rml