Just got a new boat and it has a gen 4 454 Mercruiser in it. What happen was when i went out today for the first time. Boat made it just fine. On my way back just died running 45 mph. smelt fuel and when i was able to kind of get it running fuel was just leaking all over the place and pouring out of top. Previous owner removed mechanical fuel pump and installed electric with pressure gauge and fuel lines Questions I have.

1 Did a seal in the carb just blow out ? Is that why gas was pouring out ?
2 Carb is not marine does that matter ?
3 Is it OK to run a electric fuel pump to a holly 650 or 750 car carb for a boat?
4 Is there a certain kind of carb i should use for a electric fuel pump?

Mercruiser
GEN 4
454
I/O
Carb- 650 older

DUDE GET A MARINE CARB, i run electric pumps all the time, just make sure pressure regulator is set correctly and you have an oil pressure switch so electric pumps only runs when there is oil pressure, Holley makes a kit for that, or just go back to marine mechanical pump. GET A MARINE CARB, YOU COULD HAVE HAD A FIRE OR EXPLOSION.

Why it spewed fuel could be a couple things, needle and seat stuck open, pressure regulator went to high, get new or rebuilt marine carb and figure out electric/ mechanical pump, probably easier to go back to mechanical pump, hopefully you have good access

Thanks for the help. I will get a 650 or 750 Marine Holly.I was not sure cause I have herd of people running auto carbs on boats. Also replacing that carb would be a bit cheaper if a auto carb would work.

I took a pic with gas shooting out post it after work.

X 2 As said above.

Most likely needle and seats stuck open or the n&s orings not sealing.

Marine carbs have the float vent tubes aimed back down into the throttle bores for the very reason you ran into. To redirect fuel back into engine in case needle and seats fail and let fuel fill the bowl and out the vents.

Here’s a pic of the marine style Holley

Oh, Once things are replaced and since you have a fuel psi gauge, anything between 5-7psi is considered fine.

An automotive carb would of course work but the vent tubes do not curve down into carb so when you have a problem like you had it just floods the motor and it dies, also the throttle shafts have better sealing to keep gas from leaking out. Just like a non marine alternator or starter will work but the are not spark shielded. Gas fumes are the most cause of fire due to boats having enclosed engine components. For every boat that sinks 10 boats burn to the water line.
try the wanted section here someone probably has a good carb lying around.

Also if you ever plan on insuring your boat you have to have marine carb,alternator,starter, what boat engine etc are you dealing with any other mods by previous owner

1410 eledebrock is an awesome carb to use