Mercruiser 5.0 "cutting out" w/o warning one minute in

[jsmckay]

My new used 2003 Mercruiser 5.0 alpha (carb) with 200hrs is cutting out at one minute of running w/o warning. It all started 3 weeks on the 4th of July when my warning alarm kept going off. We checked the fluids and pressures and all looked well. We decided to pull it out and replace the oil and rebuild the water pump/impeller.

It starts and runs great but keeps cutting out at +/-1 minute and will immediately resart and run for roughly the same time. We have looked and thought of the following:

-We have voltage into the ingnition coil before and after the stall
-All gauges seem in OK range
-Happens add idle and rev
-FLuids all ok
-appears to visually be getting fuel jetted into the carb at the stall
-we have checked/jumped the laniard kill swith whithout resolution
-We have "wiggled" virtually everything w/o reproducing the stall

I am not technical/mechanical but working with a friend who is. Our plan is to replace the ignition coil and check the distributer. If this fails, an other thoughts??

thanks

 

[Don S]

Re: Mercruiser 5.0 "cutting out" w/o warning one minute in

Sounds to me like the oil pressure switch that controls the electric fuel pump is faulty. The switch is just over the oil filter mount on the block (Ports side of engine block, aft.)
The switch has 2 terminals. You can test it by putting a jumper wire across the two terminals if the pump runs, start the engine and see if it keeps running.