Mastercraft running warm & rich

[Wakeless]

Hey all,<br />Lately our '94 Mastercraft ProStar 190, Indmar 5.7EFI "Corvette" w/575hrs. has been running hot after a few minutes at 3000rpm then stopping after the second skiers run. The first skier goes and it's fine, second run the boat is hot (195+/-) and has to be idled for a minute or two to cool down. Usually the third run and after is fine. It doesn't sound like an impeller problem to me, since it doesn't get hot at idle<br />Boat also runs a little rich (always has) and even worse when hot, which I think is probably built into the EFI to cool the motor, but even when it's not overheating it's noticeably rich. Is this normal? I've had the boat for 3 years, and have no idea if the boat has ever had any software updates done.

 

[snapperbait]

Re: Mastercraft running warm & rich

I would swap out the thermostat (160 degree) and probably the impeller too if it's been a while since it's been changed...<br /><br /> Make sure all the hose clamps from the intake strainer up to the raw waterpump are tight...<br /><br />As for the rich condition, I'd change out the MAP(Manifold Absolute Pressure) sensor and it's vaccum hose with new ones.... MAP sensor's main purpose is fuel rich/lean control, so any loss of vaccum or improper voltage will cause it to run rich..... You could use a MAP sensor from an autoparts store for any GM vehicle like a 1990 chevy truck for example ... <br />

<br />typical map sensor

 

[Wakeless]

Re: Mastercraft running warm & rich

What kind of readings should I see from the MAP sensor- typical of those from GM vehicles or will they be higher? I know cars (been an auto tech for going on 15 years) but I just don't know what kind of mapping Indmar puts on these boats.<br />Will an automotive scan tool work on it for viewing data?<br />Thanks for the help!