96 Mercury 4 cyl. 40 hp. shut down

[swampslider]

While cruising at approximately 4500 rpm for around 20 min. the engine shut off like the key was tuned off. It didn't sputter or slow down, just shut off. It spins with the starter but wont start. No alarms went off, the engine was not hot when it happened and there is plenty of fuel and oil and there is no lanyard emergency cut off switch. The Engine is listed as a 40 jet serial number OD297504. Any ideas what would cause it to suddenly shut off?

 

[yzf125]

Do you have spark ??

 

[swampslider]

I havent checked anything yet. It happened yesterday. I was kinda looking for some direction to start. Gonna try to start checking it out tomorrow.

 

[tlh 178]

bit of a long shot, is your kill switch on?

 

[swampslider]

I have great spark. Checked it out today and as soon as I hit the ignition it started. Im thinking I had a vapor lock. The engine ran great the last couple times out. I put a water seperator/ filter on it and Friday was the first trip out when it shut down. I checked the filter and it was clean except the gas was about a half inch below the threads. Any input would be appreciated.

 

[swampslider]

Theres no kill switch on it. Thanks for the idea though.

 

[swampslider]

Ok, rebuilt the fuel pump, it needed it, ran the motor in a large water tub for about 30-40 min. It ran great then the RPM,s dropped slightly then shut down. restarted it and it ran about 5 min. and shut down and wouldn't restart. Did an ohm check on all the coils, stator and trigger switch. they all checked out within spec's. I'm getting voltage through both the stator and the trigger to the switch box but no power on the other side of the Switch box to the coils. I am assuming the switch box is bad.

 

[Faztbullet]

Disconnect blk/yel wire off switchbox when this happen and see if spark returns,if so you have switch or harness problem. Also what was the stator voltages???

 

[swampslider]

Ok, First off I don't care what anyone says, you need a DVA meter or adapter. there is too much room for error without one.
I got a DVA adapter and checked all the voltage on the Stator, Trigger and coils and all were in spec's per the manual.Once it shut down I disconnected the blk/yel wire from the switch box and it made no difference. The switch box was definitely bad. replaced it and ran the engine for 40 minutes with no problems.
All done and I want to thank you guys for the support and guidance.