350 MAG Horizon won't start

califco

I ran both motors Sunday for 20 minutes at the dock, no issues. I tried to run again on Wednesday and my Starboard motor won't start. I tried switching gas tanks, check spark plug for a spark and battery voltages. what else could be my issue?

Stodge

I had the high pressure fuel pump fail on one of my 350 mags.  It was working one minute, dead the next.  That pump is on the bottom of the motor (versus the low pressure pump on the side) and a bear to replace.  Luckily my mechanic is good at stuff like that.  There is a port on the top of the motor where the fuel pressure can be read. It requires a (seemed to me) special gauge to read it.

reneechris14

You can just tap the valve for a second to see if you have fuel.it's just behind the thoddle body.looks like Tire valve.

califco

I found the valve and push it, fuel came out. I checked the oil pressure switch, then tried to start again with the throle on the FW direction and the motor started, as soon I placed it back in neutral the engine shut down. Tried many times until the engine stayed running. The engine ran rough and it was vibrating after 20 min it die while at idle. 
Tried again and the engine was normal, ran in neutral, FW and RV. I then took the boat to the hoist and got it on land for the winter. Not sure what happened, I was unable to tell if there was a difference while at the lake because it was so windy today. 

Dream_Inn

Sounds like the IAC valve (Idle air control).  You can remove it from the other engine very easily and try it on the faulty one.  If it's the problem you can either replace (for about 100 bucks) or try cleaning it.  It is usually two allen head bolts to remove, and it's located behind the throttle body.