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Engine will start but won’t stay running

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Kornfn12001

New member
Hey guys I have a 97 4.3 mercruiser.. I just went to start my boat from last year and the motor starts but does not continue to run.. it idles for maybe a few seconds not a full minute and dies.. one thing I do not hear is my fuel pump after it dies? Could this be the issue?
 
Electric pump? If so, it won't stay on if there's no signal that the motor has oil pressure (as a safety issue). An oil pressure switch (like an idiot light deal in a car) allows the pump to run after you let go the starting action on the key. In some cases (this one I suspect) a separate circuit runs the pump to get the motor started, then goes away when you let go the key.

Look at the oil pressure switch and its circuit to run the pump.

Jeff
 
Ayuh,.... Agreed,.... Use a jumper wire to by-pass the oil pressure switch to Test it,.....
 
Ok I’m aware I’m to by pass the switch.. my switch only has 2 wires coming off of it... and there is also what looks like a sensor.. in pictures.. it also has a wire coming off of it.. what wires do I connect? The ones on the switch are black and purple and the one on the sensor is green.. EF599330-3502-4D63-8754-6EF216C5336B.jpg4F5A5771-3E54-4DCF-B43E-05F73C62725A.jpg
 
The 1 wire is the sender for the guage. Shortthat wire to ground woth the key on and the guage should peg high oil pressure. The 2 wire switch is for the ecm, switch the key on and the fuel pump should cycle for a few seconds then jumper the two wires and the fuel pump should run. Does your oil pressure register when the engine starts?
 
Not sure about Mercruisers, but Chryslers used an oil pressure switch for the fuel pump and a sender unit for oil pressure readings. The switch had two wires on it; the sender unit only one.

Jeff
 
Ok guys! By passed the oil pressure switch this morning... boat runs great! Oil pressure is fine.. new switch comes in today thanks guys!!
 
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