EFI - Rich fuel mixture

[bubba_tiger]

I have a 2004 Mobius LSV, and this is the first season I have had it on the water. The Indmar engine is EFI (throttle body injection). I believe it is running rich because it seems to act flooded when after it is turned off and then started again (switching skiers and such). I've also noticed a black build-up on the back of the boat.

I've searched the threads and found the following (https://forum.moomba.com/showthread....h-fuel-mixture) from Larry Engelbert, Indmar Marine Engines, "Power to the Sport":

The three most likely causes of a rich running EFI engine are:
1. A faulty coolant temp sensor that is telling the ECM that the engine is cold when it is hot.
2. A MAP (Manifold Air Pressure) sensor that is telling the ECM that the manifold pressure in the engine is high when it is low.
3. High fuel pressure caused by a faulty fuel pressure regulator or by a restricted fuel return line.

My problem is that I do not know where these sensors are located. I plan on pulling the plugs to see what they look like, but I believe they were black when I pulled them to winterize the boat after we bought the boat. Any help would be appreciated!!! Thanks

[jzelt]

I would swap throttle position sensor. Did that on my Supra. Same year. 99 chevy 5.7L part from autozone did it for me.

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[bubba_tiger]

Thanks for the advice!!!

[mmandley]

Throttle body sensor on the side of the throttle body where the cable connects to open the throttle plate
MAP sensor is normally on the Air intake hose if I recall.
Temp Sensor will be near the Hot water exit hose, top of the engine.