Ok, here's the story. I ran my boat through some pretty rough waters Saturday stopping at a local hot spot for some food & drinks. When we got ready to leave my boat wouldn't start. I have a 1999 271 Formula Fastec with a 502 MPI. It was acting like I had a vapor lock in the fuel system. I would turn the key, you could here the fuel pump prime, then when I would start the boat it would spit & sputter and die. I did this for about 30 minutes before starting. Once stared it ran fine. I killed it a few times to check and make sure it would start again and fired right up. This had happened to me once last year and I changed the fuel filter thinking it was dirty and the boat ran fine the rest of our boating season. On our way back across the lake while running about 4000 RPM the boat killed while under way. When I tried to start it again I noticed the fuel pump would not come on when I turn the key on. I'm not sure if I have a bad fuel pump or something else causing this same issue. Any help pointing me in the right direction is appreciated.

First thing I'd be looking for especially after some rough running is loose wiring. That has an electric fuel pump they either work or don't there's usually not much warning wjhen they go bad. how many hours on the boat?

I agree with wiring or relay. Pumps fail completely. Had a similar problem with a procharged system. Add in fuel pump relay and wiring was the culprit. One minute I had full pressure the next I was running just on factory pump. It took a while but traced it down to a corrded wire at the relay.

I seem to recall an issue were they would vapor lock on hot days. Some guys said that if they idled in with the hatch open and or left the hatch cracked open at the dock the problem would go away. Look in the technical Q&A area?

The hard starting sounds just like vapor lock. It is common problem and my 502mpi's have done it quite a few times, especially on hot, humid days. Running ethanol fuel also contributes to the problem. Merc has a booster pump kit that will fix the vapor lock issue.

That being said, I have never heard of one stalling out at 400rpms because of vapor lock. It really can't happen. The vapor lock is caused by the fuel in the fuel line evaporating due to the engine heat while sitting for a while. The only time I've had a boat stall out at speed, it was water in the fuel. I would pull the fuel filter, dump it into a glass, let it set for a while, and then check for separation.

This just happened so I haven't had much time yet troubleshooting. I'm probably looking at 400 hours on the motor. I have looked for any loose or broken connections and haven't found any. I have pull the fuel filter and checked for water which none was found. It appears my main problem has to do with the fuel pump which is not kicking on when I turn the key on but I can here something clicking but can't seem to find it. I'm wondering if I could check the wires going to the fuel pump for power when I turn the key on. Would no power be an indication of issues before the fuel pump?

Jus a lil deeper, I too fought a very similar problem, the terminals to 1 of my perko switchs was the culprit... It would cut out in rough water @ times & others after sitting it just wouldn't get power, go jiggle the powerwires to the switch & everything would kick back on... Took it apart this spring sanded all the connections tigthened them back down hopefully it fixed my problem

I jiggled every wire I could find in the engine compartment (with no luck) to see if I could get the fuel pump to power up. I ended up pulling my fuel pump and it tested out good. Looks like my issue is getting power to the fuel pump. I guess my next move will be to locate the relay and check / inspect the wires to it. Is there a way to check the relay? Or should I just replace it (once I find it).

Get a test light and see if pump is getting power if it is replace pump.

there should be fuses on the cover that pops up on top of the motor. if the boat is still not running, i would bet the fuse is blown. the bigger problem is finding what caused the fuse to blow.