Mercruiser 350 won't start

[The Black Widow]

Hey everyone! I am actually having a problem with my ocean boat this time and I can't quite figure it out. I know some of the Tige's have mercruisers so I thought I would check here if anyone has any suggestions. It's a 1999 mercruiser mag mpi 350.

So about 4 months ago a friend filled our gas tank with water by accident. We were able to suck all the water out and ran it until now with no issues. Last weekend I noticed a lot of water in the fuel water separator after the engine stalled on a trip. We got the boat back to the dock and removed all water from the tank. I tried to start the engine and it would turn over but not start. I noticed the fuel pump wasn't cycling and found out it was bad. I replaced that today and tried to fire it up but still wouldn't start. So I started troubleshooting....

Bled the fuel line, replaced the fuel water separator, switched the ignition coil from the other working engine and checked for spark at the plugs. Everything looked good but the engine still will not start.

Any suggestions of what to check next would be great! I have reached the limits of my knowledge here.

[dom w. forte]

Suggest you check spark plugs to see if they are getting wet with fuel or fuel shrader valve, next check to see if spark is reaching the spark plugs not just out of coil.

[boatwakes]

PM me, our shop is in Newport and we're mobile up the coast to Marina Del Rey. I might be able to look at it today. -Cory

[joaquin12345]

Loosen your belt then reach down and try to turn your water pump/impeller pulley. Mercruisers have a tendency to flip the direction on the impeller especially when starting and stopping the engine. Since you have tried to start it multiple times maybe this happened to you. I had this problem 2 times now and the flipped impeller was my issue. Removed it, installed correctly and everything started up fine.