2001 mercury 5.0 runs for 30 seconds then cuts out

[regal987]

Hi let me first say thanks again to all of you using this site and offering your great advice. I have another problem with one of my newer money pits, I just bought a 2001 Maxum 2300 SR equipped with a 5.0 mercury marine engine and alpha 1 outdrive. Im not sure what is going on, if Im having a carb problem, a electric problem, or a fuel problem. the problem is it will start up like normal, no hesitation, but will only run for about 30 seconds, I tried giving it more throttle hoping to burn whatever may be in the carb, but that seems to do nothing, it just stalls quicker. Even if I try to give more throttle as it dies it does nothing and still dies. from car experience I was thinking fuel pump but kinda stumped. all input is appreciated

 

[Don S]

Re: 2001 mercury 5.0 runs for 30 seconds then cuts out

Assuming you have a carbed engine, either a bad oil pressure switch that controls the fuel pump or faulty wiring going to it.
Keeps the electric fuel pump from running unless the engine is running.

This drawing should help explain it.

 

[regal987]

Re: 2001 mercury 5.0 runs for 30 seconds then cuts out

thanks for the quick reply and awesome drawing, Do you know where I can buy a new switch?

 

[turnkey1]

Re: 2001 mercury 5.0 runs for 30 seconds then cuts out

Could I have a faulty oil pressure switch if the oil pressure is too high rather than too low? My oil pressure at idle (after the engine is warm... 130 deg.) is around 40 -60 psi, although it's impossible to tell since my reading tends to jump around a bit (no I don't have water in my oil, or a cracked head gasket). (In addition, my dipstick reads about 1qt low intentionally). The engine stalling problems with my '89 4.3 merc usually don't start showing their ugly face until I've been running the boat for about an hour. Symptoms are cough cough, backfire, engine sputter and stop. It will immediately start back up but only run for a limited period until it starts coughing again.