1st time out. Engine died, and won't start.

[Hogger]

2003 carburated 5.0L VP.
Had a shop go through the engine before we bought the boat a few months ago, they said everything looked and ran great. They winterized it.
While we had it sitting in our garage, we have cleaned it, and I upgraded the stereo, and added a second battery with a 1-2-both-off switch.

So we took the boat out for the first time today. Took a couple tries to start, but fired up, and idled smooth. I idled it out of the dock area for about 5 minutes, then brought it up to 20-25 mph, and ran it there for about 5 minutes. Then brought it up to about 30-35 mph for a couple minutes, and decided to see what it can do.
I increased the throttle to about wide open, it ran for about 10-15 seconds then sputtered like it wasn't getting gas, so I pulled the throttle back, and it ran fine. Opened it up again, it sputtered and died. I tried to start it, and it just clicked, engaged the starter, but couldn't turn over.
I tried the batteries separately, and together, and it did the same thing. Like it didn't have enough juice to turn over.
My battery switch was on both when running.
After it died the trim still went up and down.
The volt meter read about 12.5, but dropped to 0 when I tried to start it.

Could it be the batteries? They shouldn't cause the engine to die while running?
Any ideas?

 

[Bondo]

Re: 1st time out. Engine died, and won't start.

Could it be the batteries?

Ayuh,... Could be,... Or corroded wire ends....

Check the fuel filter for Water to explain the sputterin'...

 

[Don S]

Re: 1st time out. Engine died, and won't start.

Also after checking what Bond-o suggests, get the batteries load tested. They can show 12.5 volts with a meter, but have no amperage. You may also need to get the alternator tested. If it stops charging, the electric fuel pump shuts off.