Mate 229

Have a 502 Mag EFI with a procharger. When I launch the boat it fires right up and idles perfectly, also runs strong. Last week I ran about 1/2 hr then stopped for fuel, it took a lot of cranking to get the motor to fire, but didn't notice a lot of smoke when it started. Today we did the same thing even stopped for fuel, fired right up ran another 1/2 hr anchored for 1/2 hr and had trouble starting again. I plan to pull the plugs in the morning to see if anything looks strange. Any ideas? This is my first EFI motor, carbs are easier for me to look at and see whats happening.
Once the motor starts it runs strong. I don't touch the throttle when cranking, should I?

Vinny P

It sounds to me like a vapor lock condition. Check out thhe attached link....

http://www.sterndrives.com/bulletins/mc/99/EN_007.PDF

Mr Gadgets

Mate,
Try opening the throttle a bit and see if it tries to fire. I am not familiar with the Merc EFI, but it wont hurt to try it. Just crack it a bit and see what happens if nothing, then crack it somemore. I do this now on my Cutler EFI and it responds very well. If if doesnt fire right away I crack the throttle and vvaarrrrooommmmmmmmm, up it comes..

Good luck

Dick

Mate 229

Thanks for the response guys. Last time it happened I did move the throttles a little and seemed to help. The vapor lock kind of makes sense also as it was in the 90's both times it happened and really humid. The time it started after fueling I had opened the engine hatch while fueling which may have helped, I allways run the blower but don't allways open the hatch.
We have had a very hot summer in Richmond mid to high 90's and humid, hope that is the problem. Also had run the tank to empty once and really low second time, may add something to take moisture out of tank.