Merc 7.4 MPI Exhaust

[Typicall]

Hi All,<br /><br />I have a general question regarding Mercruiser 7.4 MPI engine installed in Baja 232. I have what I describe as flat at high speeds. When I get to about 3/4 throttle I hit a flat and engine will not accelerate any further even though I have throttle left. RPM is about 4000, temp is about 150-155. I run totally in saltwater. Based on past experience I feel as though I'm getting about a 10mph reduction. <br /><br />I do not know if there is any corralation with questions I am asking but these are my observations to this point. <br /> <br />I am thinking I might have a resriction in the exhaust/cooling system but am not sure.<br /><br />When decelerating I get a steam from the starboard exhaust, I also notice that when I flush seawater from engine with muffs I get very hot discharge and good volume from starboad exhaust and warm not nearly the volume from the port side.<br /><br />Is this normal? If anyone has experiance with this you help would be greatly apperciated.<br /><br />Dave

 

[vinney]

Re: Merc 7.4 MPI Exhaust

MPI engines. What is wide open rpms. next you need to check fuel pressure. I don't see exhaust restriction problem on boat except for large diesel boats. If all that is in check you need a scan tool to watch engine function. You could have the prop check for a bad hub. Smell the hub if you smell burnt rubber the hub is spun. Vinney

 

[Bondo]

Re: Merc 7.4 MPI Exhaust

How big a prop are you running ??? sounds like you've run out of HP at 4000rpms, lugging the motor......<br />Or as vinney says, hook up the "puter",+ see what's going on.......<br /><br />the exhaust sounds like it's working the way it's supposed too.......