Mercruiser 4.3 L V6 190 HP I/O Oil Pressure Sensor??

Question

Hello, I have a 2004 Mariah SC 19 Cuddy Cabin with a Mercruiser 4.3 L V6 190 HP I/O engine. About a year ago, after bringing the boat out of winter storage the engine would putter to a stop, you would start it up again no problem hit the throttle and it would putter to a stop again. First marine mechanic replaced the oil pressure sensor, the boat was put in the lake ran beautifully, turned off, we swam an hour, started it up again hit the throttle and it started to do the same thing, took the boat back they replaced the sensor again- this was at the end of the summer- this summer put the boat back in the water- it starts beautifully- runs great- get out in a cove turn the boat off swim a couple hours- start to make our way back and its doing it again. Can three sensors really fail in the period of a year or what is going on- the oil pressure guage is reading normal when the boat is running. If you hit the throttle it runs then putters out, if you let it idle it will run for longer-help

Answer 1

It sounds as if this engine has a shutdown system on it, to shut it down if it loses oil pressure or gets too hot. The first thing I would do is check for corrosion or a loose connection on that oil sensor wire. The next time it messes up try wiggling that wire or wires. If it clears up, even intermittenly, change the wire ends or look for a loose or freyed wire. The wire may even be broken inside the insulation.

The reason I'm giving this answer is because the mechanic must have known something if that sensor caused the problem before. The chances of three sensors going bad is slim to none unless something is shorting them out. Check the wires.

Answer 2

Sounds to me like ignition problems, check-out the ignition coil, that big one which goes to the distributor cap.

Some-times the windings in side break-down when hot.

Orrr fuel pump on it's way-out, could be vapour-lock too make sure there's no moisture in the gas.



Orrr maybe bad fuel-filter.

Orrr could be bad (HIGH TENSION) ignition-wire. aka

coil wire.

If the oil-pressure says good how could it be the sender?

come-on now THREE OIL-SENDERS in one year!!!!! Or is that just TWO?

sound like your shop over-stocked those dam things a are trying to flog them off.

Also check your water-separator and carburetor float-bowl for water.

Hey good luck your sure to work things-out.

P.S. How could it be the OIL-SENDER if the pressures up that's got NOTHING to do with a MOTOR STALLING-OUT?????

If the pressure is low the ALARM would sound and the gauge shouldn't lie either.

Answer 3

get the carbs checked

Answer 4

Just a wild guess!  Disconnect the wire to the sensor.  The engine should run without any guage.  What might be happening is that there is a short in the wiring that is grounding the ign. system.  and /or there is an ign. component that is faulty.  I would even check the instrument panel.  That last part sounds like a carb. problem.  You might be flooding the hot engine trying to restart-it.  Try leaving the throttle in idle, as you start the engine.  Don't use the "cold start proceedure.  There is a temp. link to the carb. have a mechanic check it with the engine at running temp.

Answer 5

Just to clarify for some of the others,your engine has a sensor and a sender.The sender lets you know that you have low oil pressure while the sensor operates the electric fuel pump once the engine is running.

I'll explain,the start circuit energizes the fuel pump,(you may hear the pump start when you turn the key to the on setting).Once the engine starts and oil pressure is built up the purple wire from the sensor then powers the fuel pump.

Since you have replaced the sensor twice and you are still having the same problem I would be looking for a reason why the the sensor is plugging up.Start with an oil change.Remove the sensor and insure that the small port in the block is clean and free of any build up or blockage.

I feel that you will have then solved the problem.

Good luck and happy boating.