Mercruiser Fuel Pump
 

I have a Mercruiser 120 fuel problem. There is a small tube going from the
fuel pump to the throat of the carburetor (like a vacuum tube) and it is
injecting a large volume of fuel into the carburetor throat, bypassing the
float assembly altogether and flooding the engine. When I remove this tube
and attempt to plug it, the engine runs properly but there is so much
pressure on this little tube it blows the plug out and starts pouring raw
fuel into the boat! Automotive engines don't have this tube, and I don't
know what it's purpose is. Can anyone offer any help? Thanks!

You need a new fuel pump. It's doing it's job when the diaphragm leaks and
dumps the fuel to the intake system versus the engine compartment. Can you
say BOOM!

"Kevin Jed" wrote in message
m...
I have a Mercruiser 120 fuel problem. There is a small tube going from the
fuel pump to the throat of the carburetor (like a vacuum tube) and it is
injecting a large volume of fuel into the carburetor throat, bypassing the
float assembly altogether and flooding the engine. When I remove this tube
and attempt to plug it, the engine runs properly but there is so much
pressure on this little tube it blows the plug out and starts pouring raw
fuel into the boat! Automotive engines don't have this tube, and I don't
know what it's purpose is. Can anyone offer any help? Thanks!

That tube is the vent side of the fuel pump diaphram. On a car it would
just be a hole in the fuel pump. When the diaphram in th epump leaks fuel
would leak out the hole. On a baot because it has a tube in it and it goes
to the carb it can't fill your bilge with gas.

"Kevin Jed" wrote in message
m...
I have a Mercruiser 120 fuel problem. There is a small tube going from the
fuel pump to the throat of the carburetor (like a vacuum tube) and it is
injecting a large volume of fuel into the carburetor throat, bypassing the
float assembly altogether and flooding the engine. When I remove this tube
and attempt to plug it, the engine runs properly but there is so much
pressure on this little tube it blows the plug out and starts pouring raw
fuel into the boat! Automotive engines don't have this tube, and I don't
know what it's purpose is. Can anyone offer any help? Thanks!

Well, I can say "Boom" but I hope I don't have to! :-)
I just never have experienced a ruptured diaphragm that supplied fuel to the
carb before. Every time I have seen a ruptured diaphragm on a fuel pump on a
car, the thing stopped supplying fuel. I didn't realize it could vent raw
fuel, I just thought it would stop pumping. That could make for a really
spectacular 4th of July type display! Thanks for the feedback! I'll pick up
a new pump first thing tomorrow morning.

"Woodchuck" wrote in message
.. .
You need a new fuel pump. It's doing it's job when the diaphragm leaks and
dumps the fuel to the intake system versus the engine compartment. Can you
say BOOM!

"Kevin Jed" wrote in message
m...
I have a Mercruiser 120 fuel problem. There is a small tube going from the
fuel pump to the throat of the carburetor (like a vacuum tube) and it is
injecting a large volume of fuel into the carburetor throat, bypassing the
float assembly altogether and flooding the engine. When I remove this tube
and attempt to plug it, the engine runs properly but there is so much
pressure on this little tube it blows the plug out and starts pouring raw
fuel into the boat! Automotive engines don't have this tube, and I don't
know what it's purpose is. Can anyone offer any help? Thanks!

Thanks for the info. I just never known of a fuel pump to do anything other
than stop supplying fuel when the diaphragm ruptures, but that makes sense
to me. I guess I'll go and pick up a new fuel pump tomorrow. Thanks again
for your reply.

"JamesgangNC" wrote in message
link.net...
That tube is the vent side of the fuel pump diaphram. On a car it would
just be a hole in the fuel pump. When the diaphram in th epump leaks fuel
would leak out the hole. On a baot because it has a tube in it and it
goes to the carb it can't fill your bilge with gas.

"Kevin Jed" wrote in message
m...
I have a Mercruiser 120 fuel problem. There is a small tube going from the
fuel pump to the throat of the carburetor (like a vacuum tube) and it is
injecting a large volume of fuel into the carburetor throat, bypassing the
float assembly altogether and flooding the engine. When I remove this tube
and attempt to plug it, the engine runs properly but there is so much
pressure on this little tube it blows the plug out and starts pouring raw
fuel into the boat! Automotive engines don't have this tube, and I don't
know what it's purpose is. Can anyone offer any help? Thanks!